diff --git "a/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" "b/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" --- "a/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" +++ "b/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" @@ -7,2778 +7,1576 @@ http://www.rssboard.org/rss-specification en-us - Tue, 09 Dec 2025 05:00:05 +0000 + Wed, 10 Dec 2025 05:00:00 +0000 rss-help@arxiv.org - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 Saturday Sunday - Tractatus Quanticum - https://arxiv.org/abs/2512.06034 - arXiv:2512.06034v1 Announce Type: new -Abstract: This is a re-editing, which takes quantum mechanics into account, of Wittgenstein's famous Tractatus. The operation has a playful side in the form, but is a serious attempt to capture possible philosophical implications of the Relational Interpretation of Quantum Mechanics, and formalize the naturalistic third-way between realism and instrumentalism explored by this interpretation. - oai:arXiv.org:2512.06034v1 + Quantum Circuit Reasoning Models: A Variational Framework for Differentiable Logical Inference + https://arxiv.org/abs/2512.07871 + arXiv:2512.07871v1 Announce Type: new +Abstract: This report introduces a novel class of reasoning architectures, termed Quantum Circuit Reasoning Models (QCRM), which extend the concept of Variational Quantum Circuits (VQC) from energy minimization and classification tasks to structured logical inference and reasoning. We posit that fundamental quantum mechanical operations, superposition, entanglement, interference, and measurement, naturally map to essential reasoning primitives such as hypothesis branching, constraint propagation, consistency enforcement, and decision making. The resulting framework combines quantum-inspired computation with differentiable optimization, enabling reasoning to emerge as a process of amplitude evolution and interference-driven selection of self-consistent states. We develop the mathematical foundation of QCRM, define its parameterized circuit architecture, and show how logical rules can be encoded as unitary transformations over proposition-qubit states. We further formalize a training objective grounded in classical gradient descent over circuit parameters and discuss simulation-based implementations on classical hardware. Finally, we propose the Quantum Reasoning Layer (QRL) as a differentiable hybrid component for composable reasoning models applicable to scientific, biomedical, and chemical inference domains. + oai:arXiv.org:2512.07871v1 quant-ph - physics.hist-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Niccol\`o Covoni, Carlo Rovelli - - - Entanglement is protected by acceleration-induced transparency in thermal field - https://arxiv.org/abs/2512.06043 - arXiv:2512.06043v1 Announce Type: new -Abstract: The acceleration-induced transparency (AIT) effect has been suggested recently to amply the transition probability of the two-level detctor and offers a potential avenue for the experimental detection of the Unruh effect. In this paper, we explore the influence of the AIT effect on quantum entanglement between two detectors accelerated in a thermal field background, since the thermal backgound field cannot be avoided completely in any experiments. Interestingly, we find that although the backgound thermal field generally degrade the entanglement between the detectors, the AIT effect can effectively protect it. - oai:arXiv.org:2512.06043v1 - quant-ph - hep-th - Tue, 09 Dec 2025 00:00:00 -0500 + cs.AI + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Yongjie Pan, Baocheng Zhang, Qingyu Cai + Andrew Kiruluta - RedCarD: A Quantum Assisted Algorithm for Fixed-Depth Unitary Synthesis via Cartan Decomposition - https://arxiv.org/abs/2512.06070 - arXiv:2512.06070v1 Announce Type: new -Abstract: A critical step in developing circuits for quantum simulation is to synthesize a desired unitary operator using the circuit building blocks. Studying unitaries and their generators from the Lie algebraic perspective has given rise to several algorithms for synthesis based on a Cartan decomposition of the dynamical Lie algebra. For unitaries of the form $e^{-itH}$, such as time-independent Hamiltonian simulation, the resulting circuits have depth that does not depend on simulation time $t$. However, finding such circuits has a large classical overhead in the cost function evaluation and the high dimensional optimization problem. In this work, by further partitioning the dynamical Lie algebra, we break down the optimization problem into smaller independent subproblems. Moreover, the resulting algebraic structure allows us to easily shift the evaluation of the cost function to the quantum computer, further cutting the classical overhead of the algorithm. As an application of the new hybrid algorithm, we synthesize the time evolution unitary for the 4-site transverse field Ising model on several IBM devices and Quantinuum's H1-1 quantum computer. - oai:arXiv.org:2512.06070v1 + The State-Operator Clifford Compatibility: A Real Algebraic Framework for Quantum Information + https://arxiv.org/abs/2512.07902 + arXiv:2512.07902v1 Announce Type: new +Abstract: We revisit the Pauli-Clifford connection to introduce a real, grade-preserving algebraic framework for $N$-qubit quantum computation based on the tensor product structure $C\ell_{2,0}(\mathbb{R})^{\otimes N}$. In this setting the bivector $J = e_{12}$ satisfies $J^{2} = -1$ and supplies the complex structure on a minimal left ideal via right-multiplication, while Pauli operations arise as left actions of suitable Clifford elements. Adopting a canonical stabilizer mapping, the $N$-qubit computational basis state $|0\cdots 0\rangle$ is represented natively by a tensor product of real algebraic idempotents. This structural choice leads to a State-Operator Clifford Compatibility law that is stable under the geometric product for $N$ qubits and aligns symbolic Clifford multiplication with unitary evolution on the Hilbert space. + oai:arXiv.org:2512.07902v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Omar Alsheikh, Efekan K\"okc\"u, Bojko N. Bakalov, A. F. Kemper + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Kagwe A. Muchane - The Twin Paradox in Quantum Field Theory - https://arxiv.org/abs/2512.06076 - arXiv:2512.06076v1 Announce Type: new -Abstract: Vacuum fluctuations in quantum field theory impose fundamental limitations on our ability to measure time in short scales. To investigate the impact of universal quantum field theory effects on observer-dependent time measurements, we introduce a clock model based on the vacuum decay probability of a finite-sized quantum system. Using this model, we study a microscopic twin paradox scenario and find that, in the smallest scales, time is not only dependent on the trajectory connecting two events, but also on how vacuum fluctuations interact with the microscopic details of the clocks. - oai:arXiv.org:2512.06076v1 + Quantum catalysis-enhanced extract energy in qubit quantum battery + https://arxiv.org/abs/2512.07906 + arXiv:2512.07906v1 Announce Type: new +Abstract: What physical mechanism enables quantum catalysis to boost quantum battery (QB) performance in open systems? We investigate an external-field-driven qubit QB coupled to a harmonic oscillator catalyst, revealing a key thermodynamic mechanism: the catalyst induces transient negative heat flow ($J(t)<0$, or energy backflow) into the battery. This backflow actively counters dephasing losses, rapidly pushing the qubit into non-passive states, and results in a drastic enhancement of extractable work (Ergotropy). Leveraging the quantum first law, we precisely quantify this causal link between negative heat flux and QB performance enhancement. Our work uncovers the fundamental role of transient thermodynamic backflow in quantum catalysis, offering a crucial blueprint for high-performance quantum energy storage devices. + oai:arXiv.org:2512.07906v1 quant-ph - gr-qc - hep-th - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Matheus H. Zambianco, T. Rick Perche + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Shun-Cai Zhao - Entanglement transition in unitary system-bath dynamics - https://arxiv.org/abs/2512.06081 - arXiv:2512.06081v1 Announce Type: new -Abstract: The evolution of a system coupled to baths is commonly described by a master equation that, in the long-time limit, yields a steady-state density matrix. However, when the same evolution is unraveled into quantum trajectories, it is possible to observe a transition in the scaling of entanglement within the system as the system-bath coupling increases - a phenomenon that is invisible in the trajectory-averaged reduced density matrix of the system. Here, we go beyond the paradigm of trajectories from master equations and explore whether a qualitatively analogous entanglement-scaling transition emerges in the unitary evolution of the combined system-bath setup. We investigate the scaling of entanglement in a unitary quantum setup composed of a 2D lattice of free fermions, where each site is coupled to a fermionic bath. Varying the system-bath coupling reveals a transition from logarithmic-law to area-law scaling, visible in the logarithmic fermionic negativity, mutual information, and also in the correlations. This occurs while the system's steady-state properties are trivial, highlighting that the signatures of these different scalings are within the bath-bath correlations. - oai:arXiv.org:2512.06081v1 + Symmetry-Based Quantum Codes Beyond the Pauli Group + https://arxiv.org/abs/2512.07908 + arXiv:2512.07908v1 Announce Type: new +Abstract: Typical stabilizer codes aim to solve the general problem of fault-tolerance without regard for the structure of a specific system. By incorporating a broader representation-theoretic perspective, we provide a generalized framework that allows the code designer to take this structure into account. For any representation of a finite group, we produce a quantum code with a code space invariant under the group action, providing passive error mitigation against errors belonging to the image of the representation. Furthermore, errors outside this scope are detected and diagnosed by performing a projective measurement onto the isotypic components corresponding to irreducible representations of the chosen group, effectively generalizing syndrome extraction to symmetry-resolved quantum measurements. We show that all stabilizer codes are a special case of this construction, including qudit stabilizer codes, and show that there is a natural one logical qubit code associated to the dihedral group. Thus we provide a unifying framework for existing codes while simultaneously facilitating symmetry-aware codes tailored to specific systems. + oai:arXiv.org:2512.07908v1 quant-ph - cond-mat.quant-gas - cond-mat.stat-mech - Tue, 09 Dec 2025 00:00:00 -0500 + math-ph + math.MP + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Bo Xing, Giuliano Chiriac\`o, Paola Cappellaro, Rosario Fazio, Dario Poletti + Zachary P. Bradshaw, Margarite L. LaBorde, Dillon Montero - High-Performance Labyrinth Circular Bragg Grating Design for Charge and Stark-Tunable Quantum Light Sources Spanning Visible to Telecom Wavelengths - https://arxiv.org/abs/2512.06117 - arXiv:2512.06117v1 Announce Type: new -Abstract: Semiconductor quantum dots embedded in circular Bragg gratings (CBGs) are among the most efficient integrated single-photon sources. However, the fully etched rings of conventional CBGs restrict the implementation of charge and Stark tuning via electrical contacts. To overcome this limitation, a labyrinth CBG geometry with four bridges has been proposed, yet the added bridges significantly degraded optical performance. In this work, we numerically demonstrate that a periodic labyrinth CBG design preserves both high coupling efficiency and strong Purcell enhancement while enabling electrical integration if optimized after introducing the bridges. We show three optimized designs at emission wavelengths of 780 nm, 930 nm, and 1550 nm, because these wavelengths are among the most relevant for quantum dots and show the general applicability of our approach. At all three wavelengths collection efficiencies exceeding 90% into a numerical aperture of 0.7 and Purcell factors greater than 25 are achieved. Furthermore, we propose a device layout incorporating a barrier layer that separates p- and n-doped semiconductor regions, which is incorporated to prevent tunneling of one of the charge carriers for selective charging. Also this design can be reoptimized to retain the performance of a device without tunnel barrier. These results establish labyrinth CBGs as a platform for electrically tunable quantum dot single-photon sources with high efficiency and scalability. - oai:arXiv.org:2512.06117v1 + Fair Benchmarking of Optimisation Applications + https://arxiv.org/abs/2512.07915 + arXiv:2512.07915v1 Announce Type: new +Abstract: Quantum optimisation is emerging as a promising approach alongside classical heuristics and specialised hardware, yet its performance is often difficult to assess fairly. Traditional benchmarking methods, rooted in digital complexity theory, do not directly capture the continuous dynamics, probabilistic outcomes, and workflow overheads of quantum and hybrid systems. This paper proposes principles and protocols for fair benchmarking of quantum optimisation, emphasising end-to-end workflows, transparency in tuning and reporting, problem diversity, and avoidance of speculative claims. By extending lessons from classical benchmarking and incorporating application-driven and energy-aware metrics, we outline a framework that enables practitioners to evaluate quantum methods responsibly, ensuring reproducibility, comparability, and trust in reported results. + oai:arXiv.org:2512.07915v1 quant-ph - physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Rohit Prasad, Quirin Buchinger, Fei Chi Kristy Yuen, Yorick Reum, Sven H\"ofling, Tobias Huber-Loyola + Frank Phillipson - Deadline-Aware Scheduling of Distributed Quantum Circuits in Near-Term Quantum Cloud - https://arxiv.org/abs/2512.06157 - arXiv:2512.06157v1 Announce Type: new -Abstract: Distributed quantum computing (DQC) enables scalable quantum computations by distributing large quantum circuits on multiple quantum processing units (QPUs) in the quantum cloud. In DQC, after partitioning quantum circuits, they must be scheduled and executed on heterogenous QPUs while balancing latency, overhead, QPU communication resource limits. However, since fully functioning quantum communication networks have not been realized yet, near-term quantum clouds will only rely on local operations and classical communication settings between QPUs, without entangled quantum links. Additionally, existing DQC scheduling frameworks do not account for user-defined execution deadlines and adopt inefficient wire cutting techniques. Accordingly, in this work, a deadline aware DQC scheduling framework with efficient wire cutting for near-term quantum cloud is proposed. The proposed framework schedules partitioned quantum subcircuits while accounting for circuit deadlines and QPU capacity limits. It also captures dependencies between partitioned subcircuits and distributes the execution of the sampling shots on different QPUs to have efficient wire cutting and faster execution. In this regard, a deadline-aware circuit scheduling optimization problem is formulated, and solved using simulated annealing. Simulation results show a marked improvement over existing shot-agnostic frameworks under urgent deadlines, reaching a 12.8% increase in requests served before their deadlines. Additionally, the proposed framework serves 8.16% more requests, on average, compared to state-of-the-art dependency-agnostic baseline frameworks, and by 9.60% versus the dependency-and-shot-agnostic baseline, all while achieving a smaller makespan of the DQC execution. Moreover, the proposed framework serves 23.7%, 24.5%, and 25.38% more requests compared to greedy, list scheduling, and random schedulers, respectively. - oai:arXiv.org:2512.06157v1 + Quantum computing of nonlinear reacting flows via the probability density function method + https://arxiv.org/abs/2512.07918 + arXiv:2512.07918v1 Announce Type: new +Abstract: Quantum computing offers the promise of speedups for scientific computations, but its application to reacting flows is hindered by nonlinear source terms and the challenges of time-dependent simulations. We present a quantum framework to address these issues. We employ a probability density function (PDF) formulation to transform the nonlinear reacting-flow governing equations into high-dimensional linear ones. The entire temporal evolution is then solved as a single large linear system using the history state method, which avoids the measurement bottleneck of conventional time-marching schemes and fully leverages the advantages of quantum linear system algorithms. To extract the quantity of interest from the resulting quantum state, we develop an efficient algorithm to measure the statistical moments of the PDF, bypassing the need for costly full-state tomography. A computational complexity analysis indicates the potential for a near-exponential speedup over classical algorithms. We validate the framework by simulating a perfectly stirred reactor, demonstrating its capability to capture the PDF evolution and statistics of a nonlinear reactive system. This work establishes a pathway for applying quantum computing to nonlinear reacting flows. + oai:arXiv.org:2512.07918v1 quant-ph - cs.NI - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Nour Dehaini, Christia Chahoud, Mahdi Chehimi + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Jizhi Zhang, Ziang Yang, Zhaoyuan Meng, Zhen Lu, Yue Yang - Collective three-body interactions enable a robust quantum speedup - https://arxiv.org/abs/2512.06170 - arXiv:2512.06170v1 Announce Type: new -Abstract: We show that collective three-body interactions (3BIs), implementable with $N$ atoms loaded inside an optical cavity, offer a significant advantage for preparing complex multipartite entangled states. Firstly, they enable a speedup of order $\sim N$ in preparing generalized Greenberger-Horne-Zeilinger (GHZ) states, outperforming conventional methods based on all-to-all two-body Ising interactions. Secondly, they saturate the Heisenberg bound in phase estimation tasks using a time-reversal protocol realized through simple rotations and followed by experimentally accessible collective spin measurements. Lastly, compared with two-body interactions (2BIs), in the presence of cavity losses and single particle decoherence, 3BIs feature a high gain in sensitivity for moderate atom numbers and in large ensembles a fast entanglement generation despite constraints in parameter regimes where they are implementable. - oai:arXiv.org:2512.06170v1 + Quantum algorithms for viscosity solutions to nonlinear Hamilton-Jacobi equations based on an entropy penalisation method + https://arxiv.org/abs/2512.07919 + arXiv:2512.07919v1 Announce Type: new +Abstract: We present a framework for efficient extraction of the viscosity solutions of nonlinear Hamilton-Jacobi equations with convex Hamiltonians. These viscosity solutions play a central role in areas such as front propagation, mean-field games, optimal control, machine learning, and a direct application to the forced Burgers' equation. Our method is based on an entropy penalisation method proposed by Gomes and Valdinoci, which generalises the Cole-Hopf transform from quadratic to general convex Hamiltonians, allowing a reformulation of viscous Hamilton-Jacobi dynamics by a discrete-time linear dynamics which approximates a linear heat-like parabolic equation, and can also extend to continuous-time dynamics. This makes the method suitable for quantum simulation. The validity of these results hold for arbitrary nonlinearity that correspond to convex Hamiltonians, and for arbitrarily long times, thus obviating a chief obstacle in most quantum algorithms for nonlinear partial differential equations. We provide quantum algorithms, both analog and digital, for extracting pointwise values, gradients, minima, and function evaluations at the minimiser of the viscosity solution, without requiring nonlinear updates or full state reconstruction. + oai:arXiv.org:2512.07919v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + math-ph + math.MP + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Haoqing Zhang, Anjun Chu, Chengyi Luo, Chitose Maruko, Eliot A. Bohr, James K. Thompson, Ana Maria Rey + http://creativecommons.org/licenses/by/4.0/ + Shi Jin, Nana Liu - Deterministic and Universal Frequency-Bin Gate for High-Dimensional Quantum Technologies - https://arxiv.org/abs/2512.06191 - arXiv:2512.06191v1 Announce Type: new -Abstract: High-dimensional photonic systems access large Hilbert spaces for quantum information processing. They offer proven advantages in quantum computation, communication, and sensing. However, implementing scalable, low-loss unitary gates across many modes remains a central challenge. Here we propose a deterministic, universal, and fully programmable high-dimensional quantum gate based on a cavity-assisted sum-frequency-generation process, achieving near-unity fidelity. The device implements an M-by-N truncated unitary transformation (with 1 <= M < N), or a full unitary when M = N, on frequency-bin modes. With current technology, the attainable dimensionality reaches M-by-N on the order of ten to the power of four, with N up to about one thousand, and can be further increased using multiple pulse shapers. Combined with compatible SPDC sources, high-efficiency detection, and fast feed-forward, this approach provides a scalable, fiber-compatible platform for high-dimensional frequency-bin quantum processing. - oai:arXiv.org:2512.06191v1 + Exchange Symmetry in Multiphoton Quantum Interference + https://arxiv.org/abs/2512.07953 + arXiv:2512.07953v1 Announce Type: new +Abstract: Photons are bosons, and yet, when prepared in specific entangled states, they can exhibit non-bosonic behaviour. While this phenomenon has so far been studied in two-photon systems, exchange symmetries and interference effects in multi-photon scenarios remain largely unexplored. In this work, we show that multi-photon states uncover a rich landscape of exchange symmetries. With three photons already, multiple pairwise combinations are possible, where each pair of photons can exhibit either bosonic, fermionic, or anyonic exchange symmetry. This gives rise to mixed symmetry systems that are not possible to achieve with two photon alone. We experimentally investigate how these symmetry configurations manifest themselves in the observed interference of three photons. We show that multi-photon interference can be effectively turned on and off by tuning the symmetry of the constituent pairs. The possibility of accessing and tuning new quantum statistics in a scalable photonic platform not only deepens our understanding of quantum systems, but is also highly relevant for quantum technologies that rely on quantum interference. + oai:arXiv.org:2512.07953v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Xin Chen + Shreya Kumar, Alex E Jones, Daniel Bhatti, Stefanie Barz - Highly robust logical qubit encoding in an ensemble of V-symmetrical qutrits - https://arxiv.org/abs/2512.06219 - arXiv:2512.06219v1 Announce Type: new -Abstract: We propose using even and odd Sch\"odinger cat states formed from coherent states of U(3) of an ensemble of qutrits with a symmetrical V-configuration (a qubit-disguised qutrit) to encode a logical qubit. These carefully engineered logical qubit states are parameter independent stationary states of the effective master equation governing the evolution of the ensemble and, consequently, constitute dark states and are invulnerable to dissipation and correlated collective dephasing. In particular, the logical qubit states are immune to single qutrit decay (the analogous of single photon loss process for qutrits) and simultaneous decay and driving of two qutrits (the analogous two-photon loss and driving processes for qutrits). In addition, we show how to implement the single-qubit quantum NOT gate and the Hadamard gate followed by either the phase gate or the phase and $Z$ gates. We study analytically the case of two qutrits and conclude that the logical qubit states exhibit parity-sensitive inhomogeneous broadening and local correlated dephasing: the even logical state is completely immune to these processes, while odd one is vulnerable. Nevertheless, in the presence of these interactions one can also define another odd state with mixed permutation symmetry that is immune to both inhomogeneous broadening and local correlated dephasing. We suggest that these results can be extrapolated to an arbitrary number of qutrits. The effective master equation is deduced from a physical system composed of two parametrically coupled cavities with one of them interacting dispersively with an ensemble of three-level atoms (the qutrits). In principle this physical system can be implemented by means of two coplanar waveguide resonators, a SQUID parametrically coupling them, and a cloud of alkali atoms close to one of the resonators. - oai:arXiv.org:2512.06219v1 + Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K + https://arxiv.org/abs/2512.07962 + arXiv:2512.07962v1 Announce Type: new +Abstract: Compared to traditional semiconductor control electronics (TSCE) located at room temperature, cryogenic single flux quantum (SFQ) electronics can provide qubit measurement and control alternatives that address critical issues related to scalability of cryogenic quantum processors. Single-qubit control and readout have been demonstrated recently using SFQ circuits coupled to superconducting qubits. Experiments where the SFQ electronics are co-located with the qubit have suffered from excess decoherence and loss due to quasiparticle poisoning of the qubit. A previous experiment by our group showed that moving the control electronics to the 3 K stage of the dilution refrigerator avoided this source of decoherence in a high-coherence 3D transmon geometry. In this paper, we also generate the pulses at the 3 K stage but have optimized the qubit design and control lines for scalable 2D transmon devices. We directly compare the qubit lifetime $T_1$, coherence time $T_2^*$ and gate fidelity when the qubit is controlled by the Josephson pulse generator (JPG) circuit versus the TSCE setup. We find agreement to within the daily fluctuations for $T_1$ and $T_2^*$, and agreement to within 10% for randomized benchmarking. We also performed interleaved randomized benchmarking on individual JPG gates demonstrating an average error per gate of $0.46$% showing good agreement with what is expected based on the qubit coherence and higher-state leakage. These results are an order of magnitude improvement in gate fidelity over our previous work and demonstrate that a Josephson microwave source operated at 3 K is a promising component for scalable qubit control. + oai:arXiv.org:2512.07962v1 quant-ph - math-ph - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.supr-con + Wed, 10 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.1063/5.0147692 + Appl. Phys. Lett. 122, 192602 (2023) + M. A. Castellanos-Beltran, A. J. Sirois, L. Howe, D. I. Olaya, J. Biesecker, S. P. Benz, P. F. Hopkins + + + Measurement-and Feedback-Driven Non-Equilibrium Phase Transitions on a Quantum Processor + https://arxiv.org/abs/2512.07966 + arXiv:2512.07966v1 Announce Type: new +Abstract: Mid-circuit measurements and feedback operations conditioned on the measurement outcomes are essential for implementing quantum error-correction on quantum hardware. When integrated in quantum many-body dynamics, they can give rise to novel non-equilibrium phase transitions both at the level of each individual quantum trajectory and the averaged quantum channel. Experimentally resolving both transitions on realistic devices has been challenging due to limitations on the fidelity and the significant latency for performing mid-circuit measurements and feedback operations in real time. Here, we develop a superconducting quantum processor that enables global mid-circuit measurement with an average quantum non-demolition (QND) fidelity of 98.7% and fast conditional feedback with a 200 ns real-time decision latency. Using this platform, we demonstrate the coexistence of an absorbing-state transition in the quantum channel and a measurement-induced entanglement transition at the level of individual quantum trajectories. For the absorbing-state transition, we experimentally extract a set of critical exponents at the transition point, which is in excellent agreement with the directed percolation universality class. Crucially, the two transitions occur at distinct values of the tuning parameter. Our results demonstrate that adaptive quantum circuits provide a powerful platform for exploring non-equilibrium quantum many-body dynamics. + oai:arXiv.org:2512.07966v1 + quant-ph + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Luis Octavio Casta\~nos-Cervantes, Manuel Calixto, Julio Guerrero + Zhiyi Wu, Xuandong Sun, Songlei Wang, Jiawei Zhang, Xiaohan Yang, Ji Chu, Jingjing Niu, Youpeng Zhong, Xiao Chen, Zhi-Cheng Yang, Dapeng Yu - Quantum Interior Point Methods: A Review of Developments and An Optimally Scaling Framework - https://arxiv.org/abs/2512.06224 - arXiv:2512.06224v1 Announce Type: new -Abstract: The growing demand for solving large-scale, data-intensive linear and conic optimization problems, particularly in applications such as artificial intelligence and machine learning, has highlighted the limitations of classical interior point methods (IPMs). Despite their favorable polynomial-time convergence, conventional IPMs often suffer from high per-iteration computational costs, especially for dense problem instances. Recent advances in quantum computing, particularly quantum linear system solvers, offer promising avenues to accelerate the most computationally intensive steps of IPMs. However, practical challenges such as quantum error, hardware noise, and sensitivity to poorly conditioned systems remain significant obstacles. In response, a series of Quantum IPMs (QIPMs) has been developed to address these challenges, incorporating techniques such as feasibility maintenance, iterative refinement, and preconditioning. In this work, we review this line of research with a focus on our recent contributions, including an almost-exact QIPM framework. This hybrid quantum-classical approach constructs and solves the Newton system entirely on a quantum computer, while performing solution updates classically. Crucially, all matrix-vector operations are executed on quantum hardware, enabling the method to achieve an optimal worst-case scalability w.r.t dimension, surpassing the scalability of existing classical and quantum IPMs. - oai:arXiv.org:2512.06224v1 + Information-Theoretic Analysis of Weak Measurements and Their Reversal + https://arxiv.org/abs/2512.08015 + arXiv:2512.08015v1 Announce Type: new +Abstract: We study trade-off relations in information extraction from quantum systems subject to null-result weak measurements, where the absence of a detected photon continuously updates the system state. We present a detailed analysis of qubit and qutrit systems and investigate a general framework for a multilevel quantum system. We develop a dynamical characterization of null-result weak measurements that quantifies the information extracted over time, revealing the amount of the obtained information and also the rate of the information accumulation. The characterizations are obtained by examining the time-dependent evolution of the information theoretic quantities. More specifically, we consider Shannon entropy, mutual information, fidelity, and relative entropy to characterize the weak measurement dynamics. Our results provide an information theoretic analysis of the weak measurement process and highlight the dynamical nature of information extraction and reversibility in the weak measurement processes. + oai:arXiv.org:2512.08015v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Mohammadhossein Mohammadisiahroudi, Zeguan Wu, Pouya Sampourmahani, Adrian Harkness, Tam\'as Terlaky + Luis D. Zambrano Palma, Yusef Maleki, M. Suhail Zubairy - Tradeoffs between quantum and classical resources in linear combination of unitaries - https://arxiv.org/abs/2512.06260 - arXiv:2512.06260v1 Announce Type: new -Abstract: The linear combination of unitaries (LCU) algorithm is a building block of many quantum algorithms. However, because LCU generally requires an ancillary system and complex controlled unitary operators, it is not regarded as a hardware-efficient routine. Recently, a randomized LCU implementation with many applications to early FTQC algorithms has been proposed that computes the same expectation values as the original LCU algorithm using a shallower quantum circuit with a single ancilla qubit, at the cost of a quadratically larger sampling overhead. In this work, we propose a quantum algorithm intermediate between the original and randomized LCU that manages the tradeoff between sampling cost and the circuit size. Our algorithm divides the set of unitary operators into several groups and then randomly samples LCU circuits from these groups to evaluate the target expectation value. Notably, we analytically prove an underlying monotonicity: larger group sizes entail smaller sampling overhead, by introducing a quantity called the reduction factor, which determines the sampling overhead across all grouping strategies. Our hybrid algorithm not only enables substantial reductions in circuit depth and ancilla-qubit usage while nearly maintaining the sampling overhead of LCU-based non-Hermitian dynamics simulators, but also achieves intermediate scaling between virtual and coherent quantum linear system solvers. It further provides a virtual ground-state preparation scheme that requires only a resettable single-ancilla qubit and asymptotically shows advantages in both virtual and coherent LCU methods. Finally, by viewing quantum error detection as an LCU process, our approach clarifies when conventional and virtual detection should be applied selectively, thereby balancing sampling and hardware overhead. - oai:arXiv.org:2512.06260v1 + Classical and quantum dynamics of a particle confined in a paraboloidal cavity + https://arxiv.org/abs/2512.08021 + arXiv:2512.08021v1 Announce Type: new +Abstract: We present a classical and quantum analysis of a particle confined in a three-dimensional paraboloidal cavity formed by two confocal paraboloids. Classically, the system is integrable and presents three independent constants of motion, namely, the energy, the $z$-component of the angular momentum, and a third dynamical constant associated with the paraboloidal geometry, which can be derived from the separability of the Hamilton--Jacobi equation. We derive closed-form analytical expressions for the actions, which allow us to determine the two conditions to get periodic closed trajectories. We classify these trajectories through the indices $(s,t,\ell)$. The caustic paraboloids that bound the motion provide a complete geometric characterization of admissible trajectories. Quantum mechanically, separability of the Schr\"odinger equation in parabolic coordinates yields eigenmodes described by Whittaker functions. We determine the energy spectrum and identify degeneracies arising not only from azimuthal symmetry but also from specific cavity deformations. A direct correspondence between classical trajectories and quantum eigenstates reveals that probability densities concentrate in the classically allowed region with controlled penetration into forbidden zones. + oai:arXiv.org:2512.08021v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + math-ph + math.MP + physics.class-ph + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kaito Wada, Hiroyuki Harada, Yasunari Suzuki, Yuuki Tokunaga, Naoki Yamamoto, Suguru Endo + \'Angel E. Reyna-Cruz, Julio C. Guti\'errez-Vega - Adiabaticity Crossover: From Anderson Localization to Planckian Diffusion - https://arxiv.org/abs/2512.06263 - arXiv:2512.06263v1 Announce Type: new -Abstract: We investigate electron transport in one dimension from the quantum-acoustic perspective, where the coherent-state representation of lattice vibrations results in a time-dependent deformation potential whose rate is set by the sound speed, fluctuation spectrum is set by the temperature, and overall amplitude is set by the electron-lattice coupling strength. We introduce an acceleration-based adiabatic criterion, consistent with the adiabatic theorem and Landau-Zener theory, that separates adiabatic and diabatic dynamics across the $(T,v)$ plane. The discrete classification agrees with a continuous mean-squared acceleration scale and correlates with a coherence measure given by the ratio of coherence length to the initial packet width $L_\phi(t)/\sigma_0$. We identify a broad Planckian domain in which the dimensionless diffusivity $\alpha\!=\!Dm/\hbar$ is of order unity and only weakly depends on the parameters. This domain is more prevalent in diabatic regions and in areas of reduced phase coherence, indicating a dephasing driven crossover from Anderson localization to Planckian diffusion. Using the Einstein relation together with nearly constant $\alpha$, we directly obtain a low temperature tendency $1/\tau_{\rm tr}\propto T$, offering a insight to $T$-linear resistivity in strange metals. These results provide a unified picture that links adiabaticity, dephasing, and Planckian diffusion in dynamically disordered quantum-acoustics. - oai:arXiv.org:2512.06263v1 + F2: Offline Reinforcement Learning for Hamiltonian Simulation via Free-Fermionic Subroutine Compilation + https://arxiv.org/abs/2512.08023 + arXiv:2512.08023v1 Announce Type: new +Abstract: Compiling shallow and accurate quantum circuits for Hamiltonian simulation remains challenging due to hardware constraints and the combinatorial complexity of minimizing gate count and circuit depth. Existing optimization method pipelines rely on hand-engineered classical heuristics, which cannot learn input-dependent structure and therefore miss substantial opportunities for circuit reduction. + We introduce \textbf{F2}, an offline reinforcement learning framework that exploits free-fermionic structure to efficiently compile Trotter-based Hamiltonian simulation circuits. F2 provides (i) a reinforcement-learning environment over classically simulatable free-fermionic subroutines, (ii) architectural and objective-level inductive biases that stabilize long-horizon value learning, and (iii) a reversible synthetic-trajectory generation mechanism that consistently yields abundant, guaranteed-successful offline data. + Across benchmarks spanning lattice models, protein fragments, and crystalline materials (12-222 qubits), F2 reduces gate count by 47\% and depth by 38\% on average relative to strong baselines (Qiskit, Cirq/OpenFermion) while maintaining average errors of $10^{-7}$. These results show that aligning deep reinforcement learning with the algebraic structure of quantum dynamics enables substantial improvements in circuit synthesis, suggesting a promising direction for scalable, learning-based quantum compilation + oai:arXiv.org:2512.08023v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.mtrl-sci + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tiange Xiang, Yubo Zhang, Joonas Keski-Rahkonen, Anton M. Graf, Eric J. Heller + http://creativecommons.org/licenses/by/4.0/ + Ethan Decker, Christopher Watson, Junyu Zhou, Yuhao Liu, Chenxu Liu, Ang Li, Gushu Li, Samuel Stein - Spin-photon Qubits for Scalable Quantum Network - https://arxiv.org/abs/2512.06285 - arXiv:2512.06285v1 Announce Type: new -Abstract: Solid-state quantum light sources offer a scalable pathway for interfacing stationary spin qubits with flying photonic qubits, forming the backbone of future quantum networks. Telecom-band spin-photonic qubits, operating in the 1260-1675 nm wavelength range, are particularly well-suited for long-distance quantum communication due to minimal loss in standard optical fibers. Achieving scalability, however, hinges on fulfilling several stringent criteria: coherent spin-state control, deterministic and indistinguishable single-photon emission, and integration with nanophotonic structures that enhance radiative properties, such as lifetime, coherence, and photon indistinguishability. This study explores the state-of-the-art spin-photonic qubits across solid-state platforms, including diamond color centers, silicon carbide defect centers, quantum dots, and two-dimensional materials. Special attention is given to silicon-based emitters, particularly G, T, C- and Ci-centers, which promise monolithic integration with complementary metal-oxide-semiconductor (CMOS) technology and telecom-band operation. We classify these systems based on spin-photon interface availability, CMOS process compatibility, and emitter scalability. We also discuss recent advances in cavity quantum electrodynamics (cQED), including Purcell enhancement and quality factor engineering in integrated photonic (circuits) environments. The work highlights emerging demonstrations of quantum networking over metropolitan scales and outlines the trajectory toward chip-scale quantum photonic integrated circuits (QPICs). It combines deterministic emitter creation, coherent spin manipulation, and quantum information processing. These developments pave the way for global quantum networks, enabling secure communication, distributed quantum computing, and quantum-enhanced sensing. - oai:arXiv.org:2512.06285v1 + Observation of a Topological Berry Phase with a Single Phonon in an Ion Microtrap Array + https://arxiv.org/abs/2512.08037 + arXiv:2512.08037v1 Announce Type: new +Abstract: Controlled quantum mechanical motion of trapped atomic ions can be used to simulate and explore collective quantum phenomena and to process quantum information. Groups of cold atomic ions in an externally applied trapping potential self-organize into "Coulomb crystals" due to their mutual electrostatic repulsion. The motion of the ions in these crystals is strongly coupled, and the eigenmodes of motion all involve multiple ions. While this enables studies of many-body physics, it limits the flexibility and tunability of the system as a quantum platform. Here, we demonstrate an array of trapped ions in individual trapping sites whose motional modes can be controllably coupled and decoupled by tuning the local applied confining potential for each ion. We show that a single motional quantum, or phonon, can be coherently shared among two or three ions confined at the vertices of an equilateral triangle 30 $\mu$m on a side. We can adiabatically tune the ion participation in the motional modes around a closed contour in configuration space, observing that the single-phonon wavefunction acquires a topological Berry phase if the contour encircles a conical intersection of motional eigenvalue surfaces. We observe this phase by single-phonon interference and study its breakdown as the motional mode tuning becomes non-adiabiatic. Our results show that precise, individual quantum control of ion motion in a two-dimensional array can provide unique access to quantum multi-body effects. + oai:arXiv.org:2512.08037v1 quant-ph - physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 + physics.atom-ph + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Md Sakibul Islam, Kuldeep Singh, Yunhe Zhao, Nitesh Singh, Wayesh Qarony + Justin F. Niedermeyer, Nathan K. Lysne, Katherine C. McCormick, Jonas Keller, Craig W. Hogle, Matthew G. Blain, Roman Schmied, Robert J\"ordens, Susanna L. Todaro, David J. Wineland, Andrew C. Wilson, Daniel H. Slichter, Dietrich Leibfried - Wigner-Husimi phase-space structure of quasi-exactly solvable sextic potential - https://arxiv.org/abs/2512.06295 - arXiv:2512.06295v1 Announce Type: new -Abstract: In this study, we compare the Wigner function $W$, its modulus, and the Husimi distribution $H$ in a one-dimensional quantum system exhibiting a transition from a single-well to a double-well configuration, using the quasi-exactly solvable sextic oscillator as a representative example. High-accuracy variational wavefunctions for the lowest states are used to compute two-dimensional phase-space structures, one-dimensional marginals, and the corresponding Shannon entropies, mutual information, and Cumulative Residual Jeffreys divergences. The analysis shows that the Wigner representation is uniquely responsive to interference effects and displays clear, nonmonotonic entropic behavior as the wells separate, whereas the modulus-Wigner and Husimi distributions account only for geometric splitting or coarse-grained delocalization. These findings establish a quantitative hierarchy in the ability of $W$, $|W|$, and $H$ to resolve structural changes in a quantum state and provide a general framework for assessing the descriptive power of different phase-space representations in systems with emerging bimodality or tunneling. - oai:arXiv.org:2512.06295v1 + Coherent and compact van der Waals transmon qubits + https://arxiv.org/abs/2512.08059 + arXiv:2512.08059v1 Announce Type: new +Abstract: State-of-the-art superconducting qubits rely on a limited set of thin-film materials. Expanding their materials palette can improve performance, extend operating regimes, and introduce new functionalities, but conventional thin-film fabrication hinders systematic exploration of new material combinations. Van der Waals (vdW) materials offer a highly modular crystalline platform that facilitates such exploration while enabling gate-tunability, higher-temperature operation, and compact qubit geometries. Yet it remains unknown whether a fully vdW superconducting qubit can support quantum coherence and what mechanisms dominate loss at both low and elevated temperatures in such a device. Here we demonstrate quantum-coherent merged-element transmons made entirely from vdW Josephson junctions. These first-generation, fully crystalline qubits achieve microsecond lifetimes in an ultra-compact footprint without external shunt capacitors. Energy relaxation measurements, together with microwave characterization of vdW capacitors, point to dielectric loss as the dominant relaxation channel up to hundreds of millikelvin. These results establish vdW materials as a viable platform for compact superconducting quantum devices. + oai:arXiv.org:2512.08059v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + cond-mat.mtrl-sci + cond-mat.supr-con + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Angelina N. Mendoza Tavera, Adrian M. Escobar Ruiz, Robin P. Sagar + Jesse Balgley, Jinho Park, Xuanjing Chu, Jiru Liu, Madisen Holbrook, Kenji Watanabe, Takashi Taniguchi, Archana Kamal, Leonardo Ranzani, Martin V. Gustafsson, James Hone, Kin Chung Fong - Entanglement Witness Derived By Using Kolmogorov-Arnold Networks - https://arxiv.org/abs/2512.06298 - arXiv:2512.06298v1 Announce Type: new -Abstract: We utilize Kolmogorov-Arnold Networks to design an interpretable model capable of detecting quantum entanglement within a set of nine-parameter two-qubit states. This network serves as an entanglement witness, achieving an accuracy of $94\%$ in distinguishing entangled states. Additionally, by analyzing the output functions of the KAN models, we explore the significance of each parameter (feature) in identifying the presence of entanglement. This analysis enables us to rank the features and eliminate the less significant ones, leading to the development of new entanglement witness functions that rely on fewer number of features, and hence do not require complete state tomography for their evaluation. - oai:arXiv.org:2512.06298v1 + On Dirac-type correlations + https://arxiv.org/abs/2512.08068 + arXiv:2512.08068v1 Announce Type: new +Abstract: Quantum correlations often defy an explanation in terms of fundamental notions of classical physics, such as causality, locality, and realism. While the mathematical theory underpinning quantum correlations between spacelike separated systems has been well-established since the 1930s, the mathematical theory for correlations between non-spacelike separated systems is much less developed. In this work, we develop the theory of what we refer to as "local-density operators", which we view as joint states for possibly non-spacelike separated quantum systems. Local-density operators are unit trace operators whose marginals are genuine density operators, which we show not only subsumes the notion of density operator, but also several extensions of the notion of density operator into the spatiotemporal domain, such as pseudo-density operators and quantum states over time. More importantly, we prove a result which establishes a one-to-one correspondence between local-density operators and what we refer to as "Dirac measures", which are complex-valued measures on the space of separable projectors associated with two quantum systems. In the case that one of the systems is the trivial quantum system with a one-dimensional Hilbert space, our result recovers the fundamental result known as Gleason's Theorem, which implies that the Born rule from quantum theory is the only way in which one may assign probabilities to the outcomes of measurements performed on quantum systems in a non-contextual manner. As such, our results establish a direct generalization of Gleason's Theorem to measurements performed on possibly non-spacelike separated systems, thus extending the mathematical theory of quantum correlations across space to quantum correlations across space and time. + oai:arXiv.org:2512.08068v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1109/ICEE67339.2025.11213574 - Fatemeh Lajevardi, Azam Mani, Ali Fahim + James Fullwood, Boyu Yang - Exploring the topology induced by non-Markovian Liouvillian exceptional points - https://arxiv.org/abs/2512.06311 - arXiv:2512.06311v1 Announce Type: new -Abstract: Non-Hermitian (NH) systems can display exotic topological phenomena without Hermitian counterparts, enabled by exceptional points (EPs). So far, investigations of NH topology have been restricted to EPs of the NH Hamiltonian, which governs the system dynamics conditional upon no quantum jumps occurring. The Liouvillian superoperator, which combines the effects of quantum jumps with NH Hamiltonian dynamics, possesses EPs (LEPs) that are significantly different from those of the corresponding NH Hamiltonian. We here study the topological features of the LEPs in the system consisting of a qubit coupled to a non-Markovian reservoir. We find that two distinct winding numbers can be simultaneously produced by executing a single closed path encircling the twofold LEP2, formed by two coinciding LEP2s, each involving a pair of coalescing eigenvectors of the extended Liouvillian superoperator. We experimentally demonstrate this purely non-Markovian phenomenon with a circuit, where a superconducting qubit is coupled to a decaying resonator which acts as a reservoir with memory effects. The results push the exploration of exceptional topology from the Markovian to non-Markovian regime. - oai:arXiv.org:2512.06311v1 + Deterministic Equations for Feedback Control of Open Quantum Systems II: Properties of the memory function + https://arxiv.org/abs/2512.08085 + arXiv:2512.08085v1 Announce Type: new +Abstract: Feedback uses past detection outcomes to dynamically modify a quantum system and is central to quantum control. These outcomes can be stored in a memory, defined as a stochastic function of past measurements. In this work, we investigate the main properties of a general memory function subject to arbitrary feedback dynamics. We show that the memory can be treated as a classical system coupled to the monitored quantum system, and that their joint evolution is described by a hybrid bipartite state. This framework allows us to introduce information-theoretic measures that quantify the correlations between the system and the memory. Furthermore, we develop a general framework to characterize the statistics of the memory -- such as moments, cumulants, and correlation functions -- which can be applied both to general feedback-control protocols and to monitored systems without feedback. As an application, we analyze feedback schemes based on detection events in a two-level system coupled to a thermal bath, focusing on protocols that stabilize either the excited-state population or Rabi oscillations against thermal dissipation. + oai:arXiv.org:2512.08085v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hao-Long Zhang, Yan Wang, Wen Ning, Shou-Bang Yang, Jia-Hao L\"u, Fan Wu, Pei-Rong Han, Zhen-Biao Yang, Shi-Biao Zheng + Alberto J. B. Rosal, Patrick P. Potts, Gabriel T. Landi - Testing the weak equivalence principle for nonclassical matter with torsion balances - https://arxiv.org/abs/2512.06333 - arXiv:2512.06333v1 Announce Type: new -Abstract: We propose tests of the weak equivalence principle (WEP) using a torsion balance, in which superposition of energy eigenstates are created in a controllable way for the test masses. After general considerations on the significance of tests of the WEP using quantum states and the need for considering inertial and gravitational masses as operators, we develop a model to derive the matrix elements of the free-fall operator, showing that the variance of the acceleration operator, in addition to its mean, enables estimation of violations of the WEP due to quantum coherence in a way that is robust with respect to shot-to-shot fluctuations. Building on this analysis, we demonstrate how the validity of the WEP may be tested in a torsion balance setup, by accessing the mean and variance of a torque operator we introduce and quantize. Due to the long acquisition times of the signal as compared to the timescale on which coherent superposition states may survive, we further propose a dynamical setting, where the torsion balance is subject to a time-dependent gravitational field, and measurements of angular acceleration encode possible violations of the WEP. - oai:arXiv.org:2512.06333v1 + On the Emergence of Time and Space in Closed Quantum Systems + https://arxiv.org/abs/2512.08120 + arXiv:2512.08120v1 Announce Type: new +Abstract: Time, space and entanglement are the main characters in this work. Their nature is still a great mystery in physics and we study here the possibility that these three phenomena are closely connected, showing how entanglement can be at the basis of the emergence of time and space within closed quantum systems. We revisit and extend the Page and Wootters theory that was originally introduced in order to describe the emergence of time through entanglement between subsystems in a globally static, quantum Universe. In the book, after providing a complete review of the salient aspects of the theory, we establish a connection with recent research on the foundations of statistical mechanics and we propose a new understanding of the thermalization process. Furthermore, we generalize the framework in order describe the spatial degree of freedom and we provide a model of 3+1 dimensional, quantum spacetime emerging from entanglement among different subsystems in a globally "timeless" and "positionless" Universe. Finally, via the Page and Wootters theory, the evolution of quantum clocks within a gravitational field is treated and a time dilation effect is obtained in agreement with the Schwarzschild solution. + oai:arXiv.org:2512.08120v1 quant-ph gr-qc - hep-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 10.1103/r2ts-fsjj - Physical Review D 112, 124014 (2025) - Roberto Onofrio, Alexander R. H. Smith, Lorenza Viola + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1007/978-3-031-52352-6 + T. Favalli, On the Emergence of Time and Space in Closed Quantum Systems, Springer Cham, 2024 + Tommaso Favalli - Bound state in the continuum and multiple atom state transfer applications in a waveguide QED setup - https://arxiv.org/abs/2512.06365 - arXiv:2512.06365v1 Announce Type: new -Abstract: Bound states in the continuum (BICs) have been extensively exploited to enhance light--matter interactions in metamaterials, yet their emergence and utility in multi-atom waveguide platforms remain far less explored. Here we study atom--waveguide-dressed BICs in a one-dimensional coupled-resonator waveguide, where two spatially separated atomic arrays couple to distinct resonators with time-dependent strengths. We show that these BICs support a standing-wave photonic mode and enable the transfer of an arbitrary unknown quantum state between the two arrays with fidelities exceeding $99\%$. The protocol remains robust against both disorder and intrinsic dissipation. Our results establish BICs as long-lived resources for high-fidelity quantum information processing in waveguide-QED architectures. - oai:arXiv.org:2512.06365v1 + The strength of weak coupling + https://arxiv.org/abs/2512.08141 + arXiv:2512.08141v1 Announce Type: new +Abstract: A paradoxical idea in quantum transport is that attaching weakly-coupled edges to a large base graph creates high-fidelity quantum state transfer. We provide a mathematical treatment that rigorously prove this folklore idea. Our proofs are elementary and build upon the Feshbach-Schur method from perturbation theory. We also show the idea is effective in circumventing Anderson localization in spin chains and finding speedups in hitting times useful for quantum search. + oai:arXiv.org:2512.08141v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + math.CO + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/publicdomain/zero/1.0/ - Xiang Guo, Xiaojun Zhang, Mingzhu Weng, Qian Bin, Hao-di Liu, Hai-Jun Xing, Xin-You L\"u, Zhihai Wang + http://creativecommons.org/licenses/by/4.0/ + Alastair Kay, Christino Tamon - Mitigating the Transition of SiV$^-$ in Diamond to an Optically Dark State - https://arxiv.org/abs/2512.06389 - arXiv:2512.06389v1 Announce Type: new -Abstract: Negatively charged silicon vacancy centers in diamond (SiV$^-$) are promising for quantum photonic technologies. However, when subject to resonant optical excitation, they can inadvertently transfer into a zero-spin optically dark state. We show that this unwanted change of charge state can be quickly reversed by the resonant laser itself in combination with static electric fields. By defining interdigitated metallic contacts on the diamond surface, we increase the steady-state SiV$^-$ photoluminescence under resonant excitation by a factor $\ge3$ for most emitters, making it practically constant for certain individual emitters. We electrically activate single \sivs near the positively biased electrode, which are entirely dark without applying local electric fields. Using time-resolved 3-color experiments, we show that the resonant laser not only excites the SiV$^-$, but also creates free holes that convert SiV$^{2-}$ to SiV$^-$ on a timescale of milliseconds. Through analysis of several individual emitters, our results show that the degree of electrical charge state controllability differs between individual emitters, indicating that their local environment plays a key role. Our proposed electric-field-based stabilization scheme enhances deterministic charge state control in group-IV color centers and improves its understanding, offering a scalable path toward quantum applications such as entanglement generation and quantum key distribution. - oai:arXiv.org:2512.06389v1 + Detecting quantum many-body states with imperfect measuring devices + https://arxiv.org/abs/2512.08150 + arXiv:2512.08150v1 Announce Type: new +Abstract: We study a coarse-graining map arising from incomplete and imperfect addressing of particles in a multipartite quantum system. In its simplest form, corresponding to a two-qubit state, the resulting channel produces a convex mixture of the two partial traces. We derive the probability density of obtaining a given coarse-grained state, using geometric arguments for two qubits coarse-grained to one, and random-matrix methods for larger systems. As the number of qubits increases, the probability density sharply concentrates around the maximally mixed state, making nearly pure coarse-grained states increasingly unlikely. For two qubits, we also compute the inverse state needed to characterize the effective dynamics under coarse-graining and find that the average preimage of the maximally mixed state contains a finite singlet component. Finally, we validate the analytical predictions by inferring the underlying probabilities from Monte-Carlo-generated coarse-grained statistics. + oai:arXiv.org:2512.08150v1 quant-ph - cond-mat.mes-hall - cond-mat.mtrl-sci - physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Manuel Rieger, Rubek Poudel, Tobias Waldmann, Lina M. Todenhagen, Stefan Kresta, Nori N. Chavira Leal, Viviana Villafa\~ne, Martin S. Brandt, Kai M\"uller, Jonathan J. Finley + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + K. Uriostegui, C. Pineda, C. Chryssomalakos, V. Rasc\'on Barajas, I. V\'azquez Mota - Generalized product-form monogamy relations in multi-qubit systems - https://arxiv.org/abs/2512.06418 - arXiv:2512.06418v1 Announce Type: new -Abstract: Monogamy of entanglement essentially characterizes the entanglement distributions among the subsystems. Generally it is given by summation-form monogamy inequalities. In this paper, we present the product-form monogamy inequalities satisfied by the $\nu$-th ($\nu\geq2$) power of the concurrence. We show that they are tighter than the existing ones by detailed example. We then establish tighter product-form monogamy inequalities based on the negativity. We show that they are valid even for high dimensional states to which the well-known CKW inequality is violated. - oai:arXiv.org:2512.06418v1 + Large-scale Lindblad learning from time-series data + https://arxiv.org/abs/2512.08165 + arXiv:2512.08165v1 Announce Type: new +Abstract: In this work, we develop a protocol for learning a time-independent Lindblad model for operations that can be applied repeatedly on a quantum computer. The protocol is highly scalable for models with local interactions and is in principle insensitive to state-preparation errors. At its core, the protocol forms a linear system of equations for the model parameters in terms of a set of observable values and their gradients. The required gradient information is obtained by fitting time-series data with sums of exponentially damped sinusoids and differentiating those curves. We develop a robust curve-fitting procedure that finds the most parsimonious representation of the data up to shot noise. We demonstrate the approach by learning the Lindbladian for a full layer of gates on a 156-qubit superconducting quantum processor, providing the first learning experiment of this kind. We study the effects of state-preparation and measurement errors and limitations on the operations that can be learned. For improved performance under readout errors, we propose an optional fine-tuning strategy that improves the fit between the time-evolved model and the measured data. + oai:arXiv.org:2512.08165v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 10.1088/1555-6611/ae2096 - Laser Phys. 35 (2025) 125201 (6pp) - Wen Zhou, Zhong-Xi Shen, Hong-Xing Wu, Zhi-Xi Wang, Shao-Ming Fei + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Ewout van den Berg, Brad Mitchell, Ken Xuan Wei, Moein Malekakhlagh - Hybrid qubit-oscillator module with motional states of two trapped interacting atoms - https://arxiv.org/abs/2512.06429 - arXiv:2512.06429v1 Announce Type: new -Abstract: We propose the use of motional states of two interacting atoms trapped in a potential stroboscopically engineered by an optical tweezer as a means to implement a qubit-oscillator system, in analogy to those implemented in circuit quantum electrodynamics and trapped ions. In our setting, the center of mass degree of freedom of the atoms plays the role of a photon or phonon mode, while the interacting, relative mode acts as a qubit. No internal state is involved in our system, which makes this motional qubit robust to spin-dependent noise. We show that a universal set of bosonic operations, including displacement, rotation, squeezing, and the corresponding set of gates controlled by the qubit, can be implemented through precise temporal modulation of the optical tweezers. We numerically check that these gates can be generated with high fidelity, and discuss possible schemes for initial state preparation and final state readout. While we restrict the discussion to a single qubit-oscillator module, scalability can be achieved by coupling arrays of atoms via dipolar or Rydberg-dressed interactions. - oai:arXiv.org:2512.06429v1 + The utility of noiseless linear amplification and attenuation in single-rail discrete-variable quantum communications + https://arxiv.org/abs/2512.08255 + arXiv:2512.08255v1 Announce Type: new +Abstract: Quantum communication offers many applications, with teleportation and superdense coding being two of the most fundamental. In these protocols, pre-shared entanglement enables either the faithful transfer of quantum states or the transmission of more information than is possible classically. However, channel losses degrade the shared states, reducing teleportation fidelity and the information advantage in superdense coding. Here, we investigate how to mitigate these effects by optimising the measurements applied by the communicating parties. We formulate the problem as an optimisation over general positive operator-valued measurements (POVMs) and compare the results with physically realisable noiseless attenuation (NA) and noiseless linear amplification (NLA) circuits. For teleportation, NLA/NA and optimised POVMs improve the average fidelity by up to 78% while maintaining feasible success probabilities. For superdense coding, they enhance the quantum advantage over the classical channel capacity by more than 100% in some regimes and shift the break-even point, thereby extending the tolerable range of losses. Notably, the optimal POVMs effectively reduce to NA or NLA, showing that simple, experimentally accessible operations already capture the essential performance gains. + oai:arXiv.org:2512.08255v1 quant-ph - physics.atom-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Jaeyong Hwang, Tianrui Xu, Sean R. Muleady, Steven Pampel, Gur Lubin, Dawson Hewatt, Cindy A. Regal, Ana Maria Rey + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Ozlem Erkilic, Aritra Das, Angela A. Baiju, Nicholas Zaunders, Biveen Shajilal, Timothy C. Ralph - Nonreciprocal photon blockade in a spinning microwave magnomechanical system through kerr-magnon and optical parametric amplifier - https://arxiv.org/abs/2512.06453 - arXiv:2512.06453v1 Announce Type: new -Abstract: Unconventional quantum antibunching, arising from quantum interference effects, represents a notable form of quantum correlation that has attracted significant attention for its ability to generate high-quality single-quantum sources. In this work, we propose a scheme to achieve and actively control strong photon blockade in a spinning microwave magnomechanical system by leveraging the combined nonlinear effects of Kerr-induced magnon interactions and an optical parametric amplifier. By exploiting the Sagnac-Fizeau shift, we establish nonreciprocal photon blockade and verify this effect through a combination of analytical modelling and numerical simulations. To gain intuitive insight into the underlying nonreciprocity, we approximate the equal-time second-order correlation function using the analytical solution of the Schr\"odinger equation. This analytical result is then compared with the full numerical solution derived from the Lindblad master equation. The influences of thermal noise, the probe field amplitude, and the magnetic-dipole coupling strength are investigated within the constraints of the weak-coupling regime. The system's nonclassicality is characterized using the Mandel parameter, complemented by an analysis of the time evolution of the second-order correlation function. Our work provides a pathway for realizing nonreciprocal photon blockade in a nonlinear spinning microwave magnomechanical system. - oai:arXiv.org:2512.06453v1 + Programmable Open Quantum Systems + https://arxiv.org/abs/2512.08279 + arXiv:2512.08279v1 Announce Type: new +Abstract: Programmability is a unifying paradigm for enacting families of quantum transformations via fixed processors and program states, with a fundamental role and broad impact in quantum computation and control. While there has been a shift from viewing open systems solely as a source of error to treating them as a computational resource, their programmability remains largely unexplored. In this work, we develop a framework that characterizes and quantifies the programmability of Lindbladian semigroups by combining physically implementable retrieval maps with time varying program states. Within this framework, we identify quantum programmable classes enabled by symmetry and stochastic structure, including covariant semigroups and fully dissipative Pauli Lindbladians with finite program dimension. We further provide a necessary condition for physical programmability that rules out coherent generators and typical dissipators generating amplitude damping. For such nonphysically programmable cases, we construct explicit protocols with finite resources. Finally, we introduce an operational programming cost, defined via the number of samples required to program the Lindbladian, and establish its core structural properties, such as continuity and faithfulness. These results provide a notion of programming cost for Lindbladians, bridge programmable channel theory and open system dynamics, and yield symmetry driven compression schemes and actionable resource estimates for semigroup simulation and control in noisy quantum technologies. + oai:arXiv.org:2512.08279v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - S. K. Singh, Mohamed Amazioug, Jia-Xin Peng, Mohammad Khalid + http://creativecommons.org/licenses/by/4.0/ + Mingrui Jing, Mengbo Guo, Lin Zhu, Hongshun Yao, Xin Wang - Scheduling Lattice Surgery with Magic State Cultivation - https://arxiv.org/abs/2512.06484 - arXiv:2512.06484v1 Announce Type: new -Abstract: Fault-tolerant quantum computation using surface codes relies on efficient scheduling of non-Clifford operations, realized via the injection of magic states produced through a probabilistic process that dominates spacetime costs. Existing scheduling approaches use dedicated bus qubits for routing and separate peripheral ancilla qubit factories for magic state preparation, leading to inefficient resource utilization. With the advent of magic state cultivation, preparation qubits can be placed anywhere within the surface code architecture. We introduce Pure Magic scheduling, which dynamically re-purposes magic state cultivation qubits for routing operations, eliminating dedicated bus infrastructure. By interrupting cultivation when qubits are needed for routing, Pure Magic naturally favors shorter cultivation times while ensuring no ancilla qubit remains idle. Our evaluation across 17 benchmark circuits improves scheduling efficiency by 19% to 223% compared to traditional bus routing and decreases average magic state preparation time by 2.6x to 9.7x. Benefits scale with circuit parallelism, making Pure Magic particularly valuable for highly parallel quantum algorithms. The Pure Magic architecture represents a paradigm shift from static to dynamic, demand-driven scheduling in fault-tolerant quantum architectures. - oai:arXiv.org:2512.06484v1 + Discovering novel quantum dynamics with NISQ simulators + https://arxiv.org/abs/2512.08293 + arXiv:2512.08293v1 Announce Type: new +Abstract: Major technological advances of the past century are rooted in our understanding of quantum physics in the non-interacting limit. A central challenge today is to understand the behavior of complex quantum many-body systems, where interactions play an essential role. About four decades ago, Richard Feynman proposed using controllable quantum systems to efficiently simulate complex physics and chemistry problems, envisioning quantum orreries, highly tunable quantum devices built to emulate less understood quantum systems. Here we ask whether quantum simulators have already uncovered new physical phenomena-and, if so, in which areas and with what impact. We find that, in several notable instances, they have advanced our understanding of many-body quantum dynamics. Although many of these insights could in principle have been obtained theoretically or numerically, they were nevertheless first achieved using quantum processors. While a broad landscape of problems beyond non-equilibrium dynamics still awaits exploration, it is encouraging that quantum simulators are already beginning to challenge and refine our conventional wisdom. + oai:arXiv.org:2512.08293v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Steven Hofmeyr, Mathias Weiden, Justin Kalloor, John Kubiatowicz, Costin Iancu + Pedram Roushan, Leigh S. Martin - Efficient quantum algorithm for solving differential equations with Fourier nonlinearity via Koopman linearization - https://arxiv.org/abs/2512.06488 - arXiv:2512.06488v1 Announce Type: new -Abstract: Quantum algorithms offer an exponential advantage with respect to the number of dependent variables for solving certain nonlinear ordinary differential equations (ODEs). These algorithms typically begin by transforming the original nonlinear ODE into a higher-dimensional linear ODE using a linearization technique, most commonly Carleman linearization. Existing works restrict their analysis to ODEs where the nonlinearities are polynomial functions of the dependent variables, significantly limiting their applicability. In this work we construct an efficient quantum algorithm for solving ODEs with `Fourier' nonlinear terms expressible as $d{\bf u}/dt = G_0 + G_1 e^{i{\bf u}}$, where ${\bf u}$ denotes a vector of $n$ complex variables evolving with $t$, $G_0$ is an $n$-dimensional complex vector, $G_1$ is an $n \times n$ complex matrix and $e^{i{\bf u}}$ denotes the vector with entries $\{e^{iu_j}\}$. To tackle the Fourier nonlinear term, which is not expressible as a finite sum of polynomials of ${\bf u}$, our algorithm employs a generalization of the Carleman linearization technique known as Koopman linearization. We also make other methodological advances towards relaxing the stringent dissipativity condition required for efficient solution extraction and towards integrated readout of classical quantities from the solution state. Our results open avenues to the development of efficient quantum algorithms for a significantly wider class of high-dimensional nonlinear ODEs, thereby broadening the scope of their applications. - oai:arXiv.org:2512.06488v1 + Quantum-classical correspondence in resonant and nonresonant Rabi-Stark model + https://arxiv.org/abs/2512.08303 + arXiv:2512.08303v1 Announce Type: new +Abstract: Testing the correspondence principle in nonlinear quantum systems is a fundamental pursuit in quantum physics. In this paper, we employed mean field approximation theory to study the semiclassical dynamics in the Rabi-Stark model (RSM) and showed that the nonlinear Stark coupling significantly modulates the semiclassical phase space structure. By analyzing the linear entanglement entropy of coherent states prepared in the classical chaotic and regular regions of the semiclassical phase space, we demonstrate that quantum-classical correspondence can be achieved in the RSM with large atom-light frequency ratios. While this correspondence fails in the resonant Rabi model because its truncated photon number is insufficient to approach the large quantum number limit, we discovered that in the resonant RSM when the nonlinear Stark coupling $U \to \pm 1$, the time-averaged linear entanglement entropy correlates strongly with the semiclassical phase space. In particular, when $U \to -1$, the truncated photon number in the resonant RSM is very close to that in the resonant Rabi model, but the time-averaged linear entanglement entropy still corresponds well with the semiclassical phase space. This result demonstrates that quantum-classical correspondence can be realized in the few-body resonant RSM. + oai:arXiv.org:2512.08303v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Judd Katz, Gopikrishnan Muraleedharan, Abhijeet Alase + http://creativecommons.org/licenses/by/4.0/ + Shangyun Wang, Songbai Chen, Jiliang Jing - Solving larger Travelling Salesman Problem networks with a penalty-free Variational Quantum Algorithm - https://arxiv.org/abs/2512.06523 - arXiv:2512.06523v1 Announce Type: new -Abstract: The Travelling Salesman Problem (TSP) is a well-known NP-Hard combinatorial optimisation problem, with industrial use cases such as last-mile delivery. Although TSP has been studied extensively on quantum computers, it is rare to find quantum solutions of TSP network with more than a dozen locations. In this paper, we present high quality solutions in noise-free Qiskit simulations of networks with up to twelve locations using a hybrid penalty-free, circuit-model, Variational Quantum Algorithm (VQA). Noisy qubits are also simulated. To our knowledge, this is the first successful VQA simulation of a twelve-location TSP on circuit-model devices. Multiple encoding strategies, including factorial, non-factorial, and Gray encoding are evaluated. Our formulation scales as $\mathcal{O}(nlog_2(n))$ qubits, requiring only 29 qubits for twelve locations, compared with over 100 qubits for conventional approaches scaling as $\mathcal{O}(n^2)$. Computational time is further reduced by almost two orders of magnitude through the use of Simultaneous Perturbation Stochastic Approximation (SPSA) gradient estimation and cost-function caching. We also introduce a novel machine-learning model, and benchmark both quantum and classical approaches against a Monte Carlo baseline. The VQA outperforms the classical machine-learning approach, and performs similarly to Monte Carlo for the small networks simulated. Additionally, the results indicate a trend toward improved performance with problem size, outlining a pathway to solving larger TSP instances on quantum devices. - oai:arXiv.org:2512.06523v1 + Photonic Quantum-Accelerated Machine Learning + https://arxiv.org/abs/2512.08318 + arXiv:2512.08318v1 Announce Type: new +Abstract: Machine learning is widely applied in modern society, but has yet to capitalise on the unique benefits offered by quantum resources. Boson sampling -- a quantum-interference based sampling protocol -- is a resource that is classically hard to simulate and can be implemented on current quantum hardware. Here, we present a quantum accelerator for classical machine learning, using boson sampling to provide a high-dimensional quantum fingerprint for reservoir computing. We show robust performance improvements under various conditions: imperfect photon sources down to complete distinguishability; scenarios with severe class imbalances, classifying both handwritten digits and biomedical images; and sparse data, maintaining model accuracy with twenty times less training data. Crucially, we demonstrate the acceleration and scalability of our scheme on a photonic quantum processing unit, providing the first experimental validation that boson-sampling-enhanced learning delivers real performance gains on actual quantum hardware. + oai:arXiv.org:2512.08318v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daniel Goldsmith, Xing Liang, Dimitrios Makris, Hongwei Wu + Markus Rambach, Abhishek Roy, Alexei Gilchrist, Akitada Sakurai, William J. Munro, Kae Nemoto, Andrew G. White - High-harmonic generation driven by temporal-mode quantum states of light - https://arxiv.org/abs/2512.06602 - arXiv:2512.06602v1 Announce Type: new -Abstract: We develop a theoretical framework for high-harmonic generation (HHG) driven by quantum states of light based on a temporal-mode expansion of the electromagnetic field. This approach extends previous single plane-wave mode treatments to realistic pulse configurations, resolving conceptual inconsistencies arising from non-normalizable infinite plane waves and establishing consistency between analytical and numerical methods. We derive a correction factor that quantifies deviations from the single-mode approximation and show that it remains below $10^{-4}$ for intensities typical of HHG ($\sim 10^{14}~$W/cm$^2$). This result confirms that free-space HHG driven by any quantum state of light is accurately described by averaging semi-classical calculations over the Husimi distribution, with no observable genuine quantum effects. The absence of such effects is attributed to the large photon numbers ($\sim 10^{11}$) required to reach HHG intensities in free space, which render quantum fluctuations negligible. We discuss nanophotonic environments with ultrasmall mode volumes as potential platforms where few-photon strong-field processes could exhibit genuine quantum signatures. - oai:arXiv.org:2512.06602v1 + Deterministic Quantum Communication Between Fixed-Frequency Superconducting Qubits via Broadband Resonators + https://arxiv.org/abs/2512.08328 + arXiv:2512.08328v1 Announce Type: new +Abstract: Quantum communication between remote chips is essential for realizing large-scale superconducting quantum computers. For such communication, itinerant microwave photons propagating through transmission lines offer a promising approach. However, demonstrations to date have relied on frequency-tunable circuit elements to compensate for fabrication-related parameter variations between sender and receiver devices, introducing control complexity and limiting scalability. In this work, we demonstrate deterministic quantum state transfer and remote entanglement generation between fixed-frequency superconducting qubits on separate chips. To compensate for the sender-receiver mismatch, we employ a frequency-tunable photon-generation technique which enables us to adjust the photon frequency without modifying circuit parameters. To enhance the frequency tunability, we implement broadband transfer resonators composed of two coupled coplanar-waveguide resonators, achieving a bandwidth of more than 100 MHz. This broadband design enables successful quantum communication across a 30-MHz range of photon frequencies between the remote qubits. Quantum process tomography reveals state transfer fidelities of around 78% and Bell-state fidelities of around 73% across the full frequency range. Our approach avoids the complexity of the control lines and noise channels, providing a flexible pathway toward scalable quantum networks. + oai:arXiv.org:2512.08328v1 quant-ph - physics.atom-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Juan M. Gonz\'alez-Monge, Johannes Feist + Takeaki Miyamura, Zhiling Wang, Kohei Matsuura, Yoshiki Sunada, Keika Sunada, Kenshi Yuki, Jesper Ilves, Yasunobu Nakamura - Fault-Tolerant Information Processing with Quantum Weak Measurement - https://arxiv.org/abs/2512.06619 - arXiv:2512.06619v1 Announce Type: new -Abstract: Noise is an important factor that influences the reliability of information acquisition, transmission, processing, and storage. In order to suppress the inevitable noise effects, a fault-tolerant information processing approach via quantum weak measurement is proposed, where pairwise orthogonal postselected measurement bases with various tiny angles and optimal compositions of measured results are chosen as a decoding rule. The signal to be protected can be retrieved with a minimal distortion after having been transmitted through a noisy channel. Demonstrated by typical examples of encoding signal on two-level superposition state or Einstein-Podolsky-Rossen state transmitted through random telegraph noise and decoherence noises channel, the mean squared error distortion may be close to $0$ and the fault-tolerant capability could reach $1$ with finite quantum resources. To verify the availability of the proposed approach, classic coherent light and quantum coherent state are used for encoding information in the experiment. Potentially, the proposed approach may provide a solution for suppressing noise effects in long-distance quantum communication, high-sensitivity quantum sensing, and accurate quantum computation. - oai:arXiv.org:2512.06619v1 + Constraint-oriented biased quantum search for general constrained combinatorial optimization problems + https://arxiv.org/abs/2512.08384 + arXiv:2512.08384v1 Announce Type: new +Abstract: We present a quantum algorithmic routine that extends the realm of Grover-based heuristics for tackling combinatorial optimization problems with arbitrary efficiently computable objective and constraint functions. Building on previously developed quantum methods that were primarily restricted to linear constraints, we generalize the approach to encompass a broader class of problems in discrete domains. To evaluate the potential of our algorithm, we assume the existence of sufficiently advanced logical quantum hardware. With this assumption, we demonstrate that our method has the potential to outperform state-of-the-art classical solvers and heuristics in terms of both runtime scaling and solution quality. The same may be true for more realistic implementations, as the logical quantum algorithm can achieve runtime savings of up to $10^2-10^3$. + oai:arXiv.org:2512.08384v1 quant-ph - physics.app-ph - physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Qi Song, Hongjing Li, Chengxi Yu, Jingzheng Huang, Ding Wang, Peng Huang, Guihua Zeng + S\"oren Wilkening - Efficient graph-diagonal characterization of noisy states distributed over quantum networks via Bell sampling - https://arxiv.org/abs/2512.06650 - arXiv:2512.06650v1 Announce Type: new -Abstract: Graph states are an important class of entangled states that serve as a key resource for distributed information processing and communication in quantum networks. In this work, we propose a protocol that utilizes a Bell sampling subroutine to characterize the diagonal elements in the graph basis of noisy graph states distributed across a network. Our approach offers significant advantages over direct diagonal estimation using unentangled single-qubit measurements in terms of scalability. Specifically, we prove that estimating the full vector of diagonal elements requires a sample complexity that scales linearly with the number of qubits ($\mathcal{O}(n)$), providing an exponential reduction in resource overhead compared to the best known $\mathcal{O}(2^n)$ scaling of direct estimation. Furthermore, we demonstrate that global properties, such as state fidelity, can be estimated with a sample complexity independent of the network size. Finally, we present numerical results indicating that the estimation in practice is more efficient than the derived theoretical bounds. Our work thus establishes a promising technique for efficiently estimating noisy graph states in large networks under realistic experimental conditions. - oai:arXiv.org:2512.06650v1 + Practical protein-pocket hydration-site prediction for drug discovery on a quantum computer + https://arxiv.org/abs/2512.08390 + arXiv:2512.08390v1 Announce Type: new +Abstract: Demonstrating the practical utility of Noisy Intermediate-Scale Quantum (NISQ) hardware for recurrent tasks in Computer-Aided Drug Discovery is of paramount importance. We tackle this challenge by performing three-dimensional protein pockets hydration-site prediction on a quantum computer. Formulating the water placement problem as a Quadratic Unconstrained Binary Optimization (QUBO), we use a hybrid approach coupling a classical three-dimensional reference-interaction site model (3D-RISM) to an efficient quantum optimization solver, to run various hardware experiments up to 123 qubits. Matching the precision of classical approaches, our results reproduced experimental predictions on real-life protein-ligand complexes. Furthermore, through a detailed resource estimation analysis, we show that accuracy can be systematically improved with increasing number of qubits, indicating that full quantum utility is in reach. Finally, we provide evidence that advantageous situations could be found for systems where classical optimization struggles to provide optimal solutions. The method has potential for assisting simulations of protein-ligand complexes for drug lead optimization and setup of docking calculations. + oai:arXiv.org:2512.08390v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + physics.bio-ph + physics.chem-ph + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zherui Jerry Wang, Joshua Carlo A. Casapao, Naphan Benchasattabuse, Ananda G. Maity, Jordi Tura, Akihito Soeda, Michal Hajdu\v{s}ek, Rodney Van Meter, David Elkouss + http://creativecommons.org/licenses/by/4.0/ + Daniele Loco, Kisa Barkemeyer, Andre R. R. Carvalho, Jean-Philip Piquemal - Experimental demonstration of scalable quantum cryptographic conferencing - https://arxiv.org/abs/2512.06661 - arXiv:2512.06661v1 Announce Type: new -Abstract: Quantum network enables a variety of quantum information processing tasks, where multi-user quantum communication is one of the important objectives. Quantum cryptographic conferencing serves as an essential solution to establish secure keys to realize secure multi-user communications. However, existing QCC implementations have been fundamentally limited by the low probability of multi-user coincidence detection to measure or construct the Greenberger-Horne-Zeilinger (GHZ) entangled state. In this work, we report the experimental realization of QCC eliminating the need for coincidence detection, where the GHZ state is constructed by correlating detection events occurring within the coherence time, thereby greatly enhancing the success probability of GHZ-state measurement. Meanwhile, to establish and maintain high-visibility GHZ measurement among three independent users, we developed a three-party phase compensation scheme combined with precise temporal and polarization alignment within a time-bin-phase encoding framework. Furthermore, we designed an efficient pairing strategy to simplify subsequent data processing and enhance processing efficiency. Based on these techniques, we successfully performed QCC experiments over total channel losses of 66.3 dB, corresponding to 331.5 km of commercial fiber (0.2 dB/km), achieving secure key rates of 5.4 bit/s, whereas previous QCC experiments have been limited to 100 km. The results surpass the multi-user repeaterless bound in quantum networks, establishing a new regime of scalable, multi-user quantum communication and paving the way for metropolitan quantum networks. - oai:arXiv.org:2512.06661v1 + Single-Step Phase-Engineered Pulse for Active Readout Cavity Reset in Superconducting Circuits + https://arxiv.org/abs/2512.08393 + arXiv:2512.08393v1 Announce Type: new +Abstract: In a circuit QED architecture, we experimentally demonstrate a simple and hardware-efficient Single-Step Phase-Engineered (SSPE) pulse scheme for actively depopulating the readout cavity. The method appends a reset segment with tailored amplitude and phase to a normal square readout pulse. Within the linear-response regime, the optimal reset amplitude scales proportionally with the readout amplitude, while the optimal reset phase remains nearly invariant, significantly simplifying the calibration process. By characterizing the cavity photons dynamics, we show that the SSPE pulse accelerates photon depletion by up to a factor of six compared to passive free decay. We further quantify the qubit backaction induced by the readout pulse and find that the SSPE pulse yields the lowest excitation and relaxation rates compared to a Square and CLEAR pulses. Our results establish the SSPE scheme as a practical and scalable approach for achieving fast, smooth, low-backaction cavity reset in superconducting quantum circuits. + oai:arXiv.org:2512.08393v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Haotao Zhu, Zhenhua Li, Shuai Zhao, Xiaodan Lyu, Shihao Ru, Yizhi Huang, Zitong Xu, Rui Qu, Weibo Gao + Ren-Ze Zhao, Ze-An Zhao, Tian-Le Wang, Peng Wang, Sheng Zhang, Xiao-Yan Yang, Hai-Feng Zhang, Zhi-Fei Li, Yuan Wu, Zi-Hao Fu, Sheng-Ri Liu, Peng Duan, Guo-Ping Guo - Interplay between Standard Quantum Detailed Balance and Thermodynamically Consistent Entropy Production - https://arxiv.org/abs/2512.06707 - arXiv:2512.06707v1 Announce Type: new -Abstract: We demonstrate that if a quantum Markovian semigroup satisfies the standard quantum detailed balance condition, its generator admits a special representation that yields a vanishing entropy production rate. Conversely, if the generator admits a special representation adhering to the condition of thermodynamic consistency and leading to a vanishing entropy production rate, then the corresponding quantum Markovian semigroup must satisfy the standard quantum detailed balance condition. In this context, we adopt the definition of entropy production rate that is motivated by the physics literature and standard for thermodynamically consistent Lindbladians. - oai:arXiv.org:2512.06707v1 + Universal recoverability of quantum states in tracial von-Neumann algebras + https://arxiv.org/abs/2512.08418 + arXiv:2512.08418v1 Announce Type: new +Abstract: In this paper, we discuss a refinement of quantum data processing inequality for the sandwiched quasi-relative entropy $\mathcal{S}_2$ on a tracial von-Neumann algebra. The main result is a universal recoverability bound with the Petz recovery map, which was previously obtained in the finite dimensional setup. + oai:arXiv.org:2512.08418v1 quant-ph - cond-mat.stat-mech - math-ph - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 + math.OA + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xin-Hai Tong, Kohei Yoshimura, Tan Van Vu, Naruo Ohga + Saptak Bhattacharya - Witnessing Spin-Orbital Entanglement using Resonant Inelastic X-Ray Scattering - https://arxiv.org/abs/2512.06718 - arXiv:2512.06718v1 Announce Type: new -Abstract: Entanglement plays a central role in quantum technologies, yet its characterization and control in materials remain challenging. Recent developments in spectrum-based entanglement witnesses have enabled new strategies for quantifying many-body entanglement in macroscopic materials. Here, we develop a protocol for detecting spin--orbital entanglement using experiment-accessible resonant inelastic x-ray scattering (RIXS). Central to our approach is the construction of a Hermitian generator from experimentally measurable spectra, which allows us to compute the quantum Fisher information (QFI) available in spin--orbital systems. The resulting QFI provides upper bounds for $k$-producible states and thus serves as a robust witness of spin--orbital entanglement. To account for realistic experimental limitations, we further extend our framework to include relaxed QFI bounds applicable to measurements lacking full polarization resolution. - oai:arXiv.org:2512.06718v1 + Real-time heralded non-Gaussian teleportation resource-state generator + https://arxiv.org/abs/2512.08429 + arXiv:2512.08429v1 Announce Type: new +Abstract: Quantum teleportation is a fundamental quantum communications primitive that requires an entangled resource state. In the continuous-variable regime, non-Gaussian entangled resources have been shown theoretically to improve teleportation fidelity compared to Gaussian squeezed vacuum. We experimentally demonstrate a heralded two-mode resource state for non-Gaussian teleportation capable of real-time use. We characterize this state with two-mode homodyne tomography showing it has fidelity $F=0.973\pm 0.005$ with the expected resource state. Real-time use is enabled by a photon-subtraction orchestrator system performing live coincidence detection and outputting low-jitter and low-latency heralding signals. Live collection of real-time quadrature measurements of photon-subtracted states is enabled by the development of a synchronized homodyne detection server where the orchestrator system queries to collect the real-time quadrature samples corresponding to the heralded state. These results demonstrate significant advancement in enabling the use of heralded non-Gaussian states in quantum networking protocols, especially in the context of quantum repeaters, non-Gaussian quantum sensing and measurement-based quantum computing. + oai:arXiv.org:2512.08429v1 quant-ph - cond-mat.str-el - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Zecheng Shen, Shuhan Ding, Zijun Zhao, Francesco A. Evangelista, Yao Wang + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Joseph C. Chapman, Yanbao Zhang, Joseph M. Lukens, Alberto M. Marino, Eugene Dumitrescu, Yan Wang, Nicholas A. Peters - Non-Orthogonal Multiple-Access for Coherent-State Optical Quantum Communications Under Lossy Photon Channels - https://arxiv.org/abs/2512.06739 - arXiv:2512.06739v1 Announce Type: new -Abstract: Coherent states have been increasingly considered in optical quantum communications (OQCs). With the inherent non-orthogonality of coherent states, non-orthogonal multiple-access (NOMA) naturally lends itself to the implementation of multi-user OQC. However, this remains unexplored in the literature. This paper proposes a novel successive interference cancellation (SIC)-based Kennedy receiver for uplink NOMA-OQC systems, along with a new approach for power allocation of the coherent states emitted by users. The key idea is to rigorously derive the asymptotic sum-rate of the considered systems, taking into account the impact of atmospheric turbulence, background noise, and lossy photon channel. With the asymptotic sum-rate, we optimize the average number of photons (or powers) of the coherent states emitted by the users. Variable substitution and successive convex approximation (SCA) are employed to convexify and maximize the asymptotic sum-rate iteratively. A new coherent-state power allocation algorithm is developed for a small-to-medium number of users. We further develop its low-complexity variant using adaptive importance sampling, which is suitable for scenarios with a medium-to-large number of users. Simulations demonstrate that our algorithms significantly enhance the sum-rate of uplink NOMA-OQC systems using coherent states by over 20\%, compared to their alternatives. - oai:arXiv.org:2512.06739v1 + A Grover-compatible manifold optimization algorithm for quantum search + https://arxiv.org/abs/2512.08432 + arXiv:2512.08432v1 Announce Type: new +Abstract: Grover's algorithm is a fundamental quantum algorithm that offers a quadratic speedup for the unstructured search problem by alternately applying physically implementable oracle and diffusion operators. In this paper, we reformulate the unstructured search as a maximization problem on the unitary manifold and solve it via the Riemannian gradient ascent (RGA) method. To overcome the difficulty that generic RGA updates do not, in general, correspond to physically implementable quantum operators, we introduce Grover-compatible retractions to restrict RGA updates to valid oracle and diffusion operators. Theoretically, we establish a local Riemannian $\mu$-Polyak-{\L}ojasiewicz (PL) inequality with $\mu = \tfrac{1}{2}$, which yields a linear convergence rate of $1 - \kappa^{-1}$ toward the global solution. Here, the condition number $\kappa = L_{\mathrm{Rie}} / \mu$, where $L_{\mathrm{Rie}}$ denotes the Riemannian Lipschitz constant of the gradient. Taking into account both the geometry of the unitary manifold and the special structure of the cost function, we show that $L_{\mathrm{Rie}} = O(\sqrt{N})$ for problem size $N = 2^n$. Consequently, the resulting iteration complexity is $O(\sqrt{N} \log(1/\varepsilon))$ for attaining an $\varepsilon$-accurate solution, which matches the quadratic speedup of $O(\sqrt{N})$ achieved by Grover's algorithm. These results demonstrate that an optimization-based viewpoint can offer fresh conceptual insights and lead to new advances in the design of quantum algorithms. + oai:arXiv.org:2512.08432v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + math.OC + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Zhichao Dong, Xiaolin Zhou, Yongkang Chen, Wei Ni, Ekram Hossain, Xin Wang + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Zhijian Lai, Dong An, Jiang Hu, Zaiwen Wen - Non-Orthogonal Multiple Access-Based Continuous-Variable Quantum Key Distribution: Secret Key Rate Analysis and Power Allocation - https://arxiv.org/abs/2512.06748 - arXiv:2512.06748v1 Announce Type: new -Abstract: We address the multi-user quantum key distribution (QKD) problem under malicious quantum attacks, which is critical for realizing a large-scale quantum Internet. This paper maximizes the sum secret key rate (SKR) of a novel uplink non-orthogonal multiple access based continuous-variable QKD (NOMA-CVQKD) system under collective attacks. The proposed system uses Gaussian-modulated coherent states and a quantum successive interference cancellation based heterodyne receiver. We derive closed-form asymptotic bounds for the legitimate users' achievable key rates via the entropy power inequality and maximum entropy principle, as well as for the eavesdropper's intercepted information based on Holevo information. A successive convex approximation based power allocation algorithm is developed to maximize the asymptotic sum SKR of the NOMA-CVQKD system under collective attacks, with guaranteed convergence to a locally optimal Karush-Kuhn-Tucker solution. Simulation results show that the proposed NOMA-CVQKD system with the power allocation algorithm achieves up to 23% higher sum SKR than quantum-orthogonal multiple access, supports 16 users at excess noise variance 0.1, and remains robust under varying turbulence intensities and transmission distances. - oai:arXiv.org:2512.06748v1 + Benchmarking Gaussian and non-Gaussian input states with a hybrid sampling platform + https://arxiv.org/abs/2512.08433 + arXiv:2512.08433v1 Announce Type: new +Abstract: The original boson sampling paradigm-consisting of multiple single-photon input states, a large interferometer, and multi-channel click detection-was originally proposed as a photonic route to quantum computational advantage. Its non-Gaussian resources, essential for outperforming any classical system, are provided by single-photon inputs and click detection. Yet the drive toward larger experiments has led to the replacement of experimentally demanding single-photon sources with Gaussian states, thereby diminishing the available non-Gaussianity-a critical quantum resource. As the community broadens its focus from the initial sampling task to possible real-world applications, it becomes crucial to quantify the performance cost associated with reducing non-Gaussian resources and to benchmark sampling platforms that employ different input states. + To address this need, we introduce the Paderborn Quantum Sampler (PaQS), a hybrid platform capable of performing sampling experiments with eight Gaussian or non-Gaussian input states in a 12-mode interferometer within a single experimental run. This architecture enables direct, side-by-side benchmarking of distinct sampling regimes under otherwise identical conditions. By employing a semi-device-independent framework, offering certification that does not rely on prior knowledge of the interferometer or the input states, we verify that the observed data cannot be reproduced by any classical model-a prerequisite for demonstrating quantum advantage. Applying this framework, we observe clear performance gains arising from non-Gaussian input states. + oai:arXiv.org:2512.08433v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Zhichao Dong, Xiaolin Zhou, Huang Peng, Wei Ni, Ekram Hossain, Xin Wang + Michael Stefszky, Kai-Hong Luo, Jan-Lucas Eickmann, Simone Atzeni, Florian L\"utkewitte, Cheeranjiv Pandey, Fabian Schlue, Jonas Lammers, Mikhail Roiz, Timon Schapeler, Laura Ares, Milad Yahyapour, Alexander Kastner, Joschua Martinek, Michael Mittermair, Carlos Sevilla, Marius Leyendecker, Oskar Kohout, Dmitriy Mitin, Ronald Holzwarth, Jan Sperling, Tim Bartley, Fabian Steinlechner, Benjamin Brecht, Christine Silberhorn - Virtual Qudits for Simon's Problem: Dimension-Lifted Algorithms on Qubit Hardware - https://arxiv.org/abs/2512.06756 - arXiv:2512.06756v1 Announce Type: new -Abstract: Simon's problem admits an exponential quantum speedup, but current quantum devices support only qubits. This work introduces a general construction for simulating qudit versions of Simon's algorithm on qubit hardware by defining virtual qudits implemented through controlled permutations and qudit phase operations. We build a dimension lifted oracle that encodes the hidden shift in dimension d and show how to realize its action using only qubit gates. We mathematically verify that the lifted circuit reproduces the correct measurement statistics, analyze the depth overhead tradeoffs as a function of d, and provide numerical simulations in QuTiP for example values. Our approach demonstrates how higher-dimensional structures can be embedded into qubit devices and provides a general method for extending qudit algorithms to current hardware. - oai:arXiv.org:2512.06756v1 + High-OAM Deep Ultraviolet Twisted Light Generation for RF-Photoinjector Applications + https://arxiv.org/abs/2512.08442 + arXiv:2512.08442v1 Announce Type: new +Abstract: We report on the generation and characterization of ultraviolet (wavelength 266 nm) twisted light with high orbital angular momentum (OAM) using three types of fabricated diffractive optical elements (DOEs): a reflective fork grating, a high-charge spiral phase plate (SPP), and binary axicons. All elements were integrated into a drive-laser beamline of an electron RF-photoinjector, enabling direct evaluation under accelerator-relevant conditions. + The SPP produced a high-purity Laguerre-Gaussian mode with OAM l = 64 and a measured conversion efficiency of approximately 80\%. Binary axicons generated quasi-Bessel twisted light with topological charges up to m = 10, exhibiting low divergence and stable multi-lobe ring structures. The fork grating reliably produced lower-order modes, l = 2-8, with good agreement between simulations and cylindrical-lens diagnostics. + These results constitute, to our knowledge, the first comprehensive experimental demonstration of deep-UV high-OAM beams generated with fabricated DOEs and validated through mode-conversion measurements. The demonstrated techniques are compatible with high-power UV laser systems used in RF-photoinjectors and offer a practical route toward structured photocathode illumination and the generation of relativistic vortex electrons at a particle accelerator facility. + oai:arXiv.org:2512.08442v1 quant-ph - cs.CC - Tue, 09 Dec 2025 00:00:00 -0500 + physics.acc-ph + physics.optics + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Abed Semre (Computer Science Department, Technion - Israel Institute of Technology, Haifa, Israel), Steven Frankel (Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel) + A. S. Dyatlov, D. M. Dolgintsev, V. V. Gerasimov, V. V. Kobets, V. P. Nazmov, M. A. Nozdrin, A. N. Sergeev, D. S. Shokin, K. E. Yunenko, D. V. Karlovets - Enhancing ground-state interaction strength of neutral atoms via Floquet stroboscopic dynamics - https://arxiv.org/abs/2512.06760 - arXiv:2512.06760v1 Announce Type: new -Abstract: Neutral atom systems are promising platforms for quantum simulation and computation, owing to their long coherence times. However, their intrinsically weak ground-state interactions pose a major limitation to the advancement of scalable quantum simulation and computation. To address this challenge, we propose an approach to enhancing the ground-state interaction strength of neutral atoms via Floquet modulation of a Rydberg atomic ensemble. Each Floquet period consists of ground-state coupling followed by a pulse driving the transition from the ground state to the Rydberg state. Theoretical analysis and numerical simulations demonstrate that after a defined evolution time, neutral atoms within Rydberg ensembles can collectively form a $W$ state in the ground-state manifold. Even when the Rydberg interaction strength is far below the blockade regime, the fidelity remains remarkably high. Finally, we analyze the application of this scheme in the preparation of single-photon sources. In general, our proposed mechanism offers an efficient and highly controllable method for quantum state preparation within the Rydberg atomic ensembles, significantly enhancing the accuracy and stability of quantum state engineering while providing a well-controlled quantum environment for single-photon generation. - oai:arXiv.org:2512.06760v1 + Heralded generation of a three-mode NOON state + https://arxiv.org/abs/2512.08458 + arXiv:2512.08458v1 Announce Type: new +Abstract: Entangled states of photons form the foundation of quantum communication, computation, and metrology. Yet their generation remains fundamentally constrained: in the absence of intrinsic photon-photon interactions, the generation of such states is inherently probabilistic rather than deterministic. The prevalent technique of post-selection verifies the creation of an entangled state by detecting and thus destroying it. Heralding offers a solution in which measuring ancillary photons in auxiliary modes signals the state generation without the need to measure it. Here, we report an experiment to generate a three-mode two-photon NOON state, where the detection of a single photon in one heralding mode signifies the presence of the state in three target modes. We validate the generated state by estimating a fidelity of 0.823 +/- 0.018 with respect to an ideal three-mode NOON state and certifying genuine multipartite entanglement. By virtue of the high success probability and small resource overhead of our scheme, our work provides a theoretical and experimental stepping stone for entangled multi-mode state generation, which is realizable with current technology. These multi-mode entangled states represent a key direction for linear optical quantum information that is complementary to multi-qubit state encoding. + oai:arXiv.org:2512.08458v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Y. Wei, M. Artoni, G. C. La Rocca, J. H. Wu, X. Q. Shao + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sukhjit P. Singh, Elnaz Bazzazi, Diego N. Bernal-Garc\'ia, Simon White, Hassan Jamal Latief, Alison Goldingay, Sven Rogge, Sergei Slussarenko, Farzad Ghafari, Emanuele Polino, Nora Tischler - Quantum Mpemba effect in long-ranged U(1)-symmetric random circuits - https://arxiv.org/abs/2512.06775 - arXiv:2512.06775v1 Announce Type: new -Abstract: The Mpemba effect, where a state prepared farther from equilibrium relaxes faster to equilibrium than one prepared closer, has a quantum counterpart where relaxation is resolved by conserved charge. However, the fate of the quantum Mpemba effect in systems with long-range interactions remains an open question. Here, we study the quantum Mpemba effect in long-ranged, U(1)-symmetric random unitary circuits. Using annealed R\'enyi-2 entanglement asymmetry computed via replica tensor networks and exact diagonalization, we track the symmetry restoration from three types of tilted product states: ferromagnetic, antiferromagnetic, and ferromagnetic with a central domain wall. The quantum Mpemba effect is present for tilted ferromagnetic states at all interaction ranges, but absent for tilted antiferromagnetic states, and occurs for the domain-wall state only in effectively short-ranged circuits, where the Mpemba time $t_{\rm M}$ is found to scale with the subsystem size $N_A$ as $t_{\rm M}\!\sim\!N_{A}^{\,z}$, with the dynamical exponent $z=\min(\alpha-1,2)$. These results reveal how the quantum Mpemba effect is governed by the interplay between interaction range and initial-state charge bias in long-ranged chaotic systems. - oai:arXiv.org:2512.06775v1 + Higher Josephson harmonics in a tunable double-junction transmon qubit + https://arxiv.org/abs/2512.08470 + arXiv:2512.08470v1 Announce Type: new +Abstract: Tunable Josephson harmonics open up for new qubit design. We demonstrate a superconducting circuit element with a tunnel junction in series with a SQUID loop, yielding a highly magnetic-flux tunable harmonic content of the Josephson potential. We analyze spectroscopy of the first four qubit transitions with a circuit model which includes the internal mode, revealing a second harmonic up to $\sim10\%$ of the fundamental harmonic. Interestingly, a sweet spot where the dispersive shift vanishes is achieved by balancing the dispersive couplings to the internal and qubit modes. The highly tunable set-up provides a route toward protected qubits, and customizable nonlinear microwave devices. + oai:arXiv.org:2512.08470v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Han-Ze Li, Ching Hua Lee, Shuo Liu, Shi-Xin Zhang, Jian-Xin Zhong + Ksenia Shagalov, David Feldstein-Bofill, Leo Uhre Jakobsen, Zhenhai Sun, Casper Wied, Amalie T. J. Paulsen, Johann Bock Severin, Malthe A. Marciniak, Clinton A. Potts, Anders Kringh{\o}j, Jacob Hastrup, Karsten Flensberg, Svend Kr{\o}jer, Morten Kjaergaard - Maximum Independent Set via Probabilistic and Quantum Cellular Automata - https://arxiv.org/abs/2512.06778 - arXiv:2512.06778v1 Announce Type: new -Abstract: We study probabilistic cellular automata (PCA) and quantum cellular automata (QCA) as frameworks for solving the Maximum Independent Set (MIS) problem. We first introduce a synchronous PCA whose dynamics drives the system toward the manifold of maximal independent sets. Numerical evidence shows that the MIS convergence probability increases significantly as the activation probability p tends to 1, and we characterize how the steps required to reach the absorbing state scale with system size and graph connectivity. Motivated by this behavior, we construct a QCA combining a pure dissipative phase with a constraint-preserving unitary evolution that redistributes probability within this manifold. Tensor Network simulations reveal that repeated dissipative--unitary cycles concentrate population on MIS configurations. We also provide an empirical estimate of how the convergence time scales with graph size, suggesting that QCA dynamics can provide an efficient alternative to adiabatic and variational quantum optimization methods based exclusively on local and translationally invariant rules. - oai:arXiv.org:2512.06778v1 + Syntactic Structure, Quantum Weights + https://arxiv.org/abs/2512.08507 + arXiv:2512.08507v1 Announce Type: new +Abstract: Why do local actions and exponential Euclidean weights arise so universally in classical, statistical, and quantum theories? We offer a structural explanation from minimal constraints on finite descriptions of admissible histories. Assume that histories admit finite, self-delimiting (prefix-free) generative codes that can be decoded sequentially in a single forward pass. These purely syntactic requirements define a minimal descriptive cost, interpretable as a smoothed minimal program length, that is additive over local segments. First, any continuous local additive cost whose stationary sector coincides with the empirically identified classical variational sector is forced into a unique Euler--Lagrange equivalence class. Hence the universal form of an action is fixed by descriptional structure alone, while the specific microscopic Lagrangian and couplings remain system-dependent semantic input. Second, independently of microscopic stochasticity, finite prefix-free languages exhibit exponential redundancy: many distinct programs encode the same coarse history, and this redundancy induces a universal exponential multiplicity weight on histories. Requiring this weight to be real and bounded below selects a real Euclidean representative for stable local bosonic systems, yielding the standard Euclidean path-integral form. When Osterwalder--Schrader reflection positivity holds, the Euclidean measure reconstructs a unitary Lorentzian amplitude. + oai:arXiv.org:2512.08507v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Federico Dell'Anna, Matteo Grotti, Vito Giardinelli + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Kentaro Imafuku - Physics Informed Generative Machine Learning for Accelerated Quantum-centric Supercomputing - https://arxiv.org/abs/2512.06858 - arXiv:2512.06858v1 Announce Type: new -Abstract: Quantum centric supercomputing (QCSC) framework, such as sample-based quantum diagonalization (SQD) holds immense promise toward achieving practical quantum utility to solve challenging problems. QCSC leverages quantum computers to perform the classically intractable task of sampling the dominant fermionic configurations from the Hilbert space that have substantial support to a target state, followed by Hamiltonian diagonalization on a classical processor. However, noisy quantum hardware produces erroneous samples upon measurements, making robust and efficient configuration-recovery strategies essential for a scalable QCSC pipeline. Toward this, in this work, we introduce PIGen-SQD, an efficiently designed QCSC workflow that utilizes the capability of generative machine learning (ML) along with physics-informed configuration screening via implicit low-rank tensor decompositions for accurate fermionic state reconstruction. The physics-informed pruning is based on a class of efficient perturbative measures that, in conjunction with hardware samples, provide a substantial overlap with the target state. This distribution induces an anchoring effect on the generative ML models to stochastically explore only the dominant sector of the Hilbert space for effective identification of additional important configurations in a self-consistent manner. Our numerical experiments performed on IBM Heron R2 quantum processors demonstrate this synergistic workflow produces compact, high-fidelity subspaces that substantially reduce diagonalization cost while maintaining chemical accuracy under strong electronic correlations. By embedding classical many body intuitions directly into the generative ML model, PIGen-SQD advances the robustness and scalability of QCSC algorithms, offering a promising pathway toward chemically reliable quantum simulations on utility-scale quantum hardware. - oai:arXiv.org:2512.06858v1 + Tunable passive squeezing of squeezed light through unbalanced double homodyne detection + https://arxiv.org/abs/2512.08540 + arXiv:2512.08540v1 Announce Type: new +Abstract: The full characterization of quantum states of light is a central task in quantum optics and information science. Double homodyne detection provides a powerful method for the direct measurement of the Husimi Q quasi-probability distribution, offering a complete state representation in a simple experimental setting and a limited time frame. Here, we demonstrate that double homodyne detection can serve as more than a passive measurement apparatus. By intentionally unbalancing the input beamsplitter that splits the quantum signal, we show that the detection scheme itself performs an effective squeezing or anti-squeezing transformation on the state being measured. The resulting measurement directly samples the Q function of the input state as if it were acted upon by a squeezing operator whose strength is a tunable experimental parameter : the beamsplitter's reflectivity. We experimentally realize this technique using a robust polarization-encoded double homodyne detection to characterize a squeezed vacuum state. Our results demonstrate the controlled deformation of the measured Q function's phase-space distribution, confirming that unbalanced double homodyne detection is a versatile tool for simultaneous quantum state manipulation and characterization. + oai:arXiv.org:2512.08540v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + physics.optics + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Chayan Patra, Dibyendu Mondal, Sonaldeep Halder, Dipanjali Halder, Mostafizur Rahaman Laskar, Richa Goel, Rahul Maitra + Niels Tripier-Mondancin, David Barral, Gana\"el Roeland, Ra\'ul Leonardo Rincon Celis, Yann Bouchereau, Nicolas Treps - Single Flux Quantum Circuit Operation at Millikelvin Temperatures - https://arxiv.org/abs/2512.06895 - arXiv:2512.06895v1 Announce Type: new -Abstract: As quantum computing processors increase in size, there is growing interest in developing cryogenic electronics to overcome significant challenges to system scaling. Single flux-quantum (SFQ) circuits offer a promising alternative to remote, bulky, and power-hungry room temperature electronics. To meet the need for digital qubit control, readout, and co-processing, SFQ circuits must be adapted to operate at millikelvin temperatures near quantum processors. SEEQC's SFQuClass digital quantum management approach proximally places energy-efficient SFQ (ERSFQ) circuits and qubits in a multi-chip module. This enables extremely low power dissipation, compatible with a typical dilution cryostat's limited cooling power, while maintaining high processing speed and low error rates. We report on systematic testing from 4 K to 10 mK of a comprehensive set of ERSFQ cells, as well as more complex circuits such as programmable counters and demultiplexers used in digital qubit control. We compare the operating margins and error rates of these circuits and find that, at millikelvin, bias margins decrease and the center of the margins (i.e., the optimal bias current value) increases by ~15%, compared to 4.2 K. The margins can be restored by thermal annealing by reducing Josephson junction (JJ) critical current Ic. To provide guidance for how circuit parameters vary from 4.2 K to millikelvin, relevant analog process control monitors (PCMs) were tested in the temperature range of interest. The measured JJ critical current (of the PCM JJ arrays) increases by ~15% when decreasing temperature from 4.2 K to millikelvin, in good agreement with both theory and the empirically measured change in the center of bias margins for the tested digital circuits. - oai:arXiv.org:2512.06895v1 + Quantum simulation in the entanglement picture + https://arxiv.org/abs/2512.08565 + arXiv:2512.08565v1 Announce Type: new +Abstract: The notion of ``picture'' is fundamental in quantum mechanics. In this work, a new picture, which we call entanglement picture, is proposed based on the novel channel-state duality, whose importance is revealed in quantum information science. We illustrate the application of entanglement picture in quantum algorithms for the simulation of many-body dynamics, quantum field theory, thermal physics, and more generic quantities. + oai:arXiv.org:2512.08565v1 quant-ph - cond-mat.supr-con - physics.app-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Jason Walter, Adam C. Weis, Kan-Ting Tsai, Meng-Ju Yu, Naveen Katam, Alex F. Kirichenko, Oleg A. Mukhanov, Shu-Jen Han, Igor V. Vernik + http://creativecommons.org/licenses/by-nc-sa/4.0/ + D. -S. Wang, X. Xu, Y. -D. Liu - Optimal Transport of a Free Quantum Particle and its Shape Space Interpretation - https://arxiv.org/abs/2512.06940 - arXiv:2512.06940v1 Announce Type: new -Abstract: A solution of the free Schr\"odinger equation is investigated by means of Optimal transport. The curve of probability measures $\mu_t$ this solution defines is shown to be an absolutely continuous curve in the Wasserstein space $W_2(\mathbb{R}^3)$. The optimal transport map from $\mu_t$ to $\mu_s$, the cost for this transport (i.e. the Wasserstein distance) and the value of the Fisher information along $\mu_t$ are being calculated. It is finally shown that this solution of the free Schr\"odinger equation can naturally be interpreted as a curve in so-called Shape space, which forgets any positioning in space but only describes properties of shapes. In Shape space, $\mu_t$ continues to be a shortest path geodesic. - oai:arXiv.org:2512.06940v1 + $\mathcal{PT}$-symmetric cavity magnomechanics with gain-assisted transparency and amplification + https://arxiv.org/abs/2512.08612 + arXiv:2512.08612v1 Announce Type: new +Abstract: We investigate magnomechanically induced transparency in a parity-time-symmetric cavity magnomechanical system with traveling-field-induced non-Hermiticity. The setup consists of a microwave cavity mode coupled to magnons in a single-crystal yttrium iron garnet sphere, which in turn are hybridized with a vibrational mechanical mode through magnetostrictive interaction. In the Hermitian regime, strong photon-magnon coupling generates a single transparency window in the cavity transmission, which splits into a doublet when the magnon is coherently hybridized with the mechanical mode via magnomechanical coupling. This establishes a versatile platform in which the transparency spectrum can be engineered from single- to multi-window response using experimentally accessible, scaled magnomechanical interactions. When a non-Hermitian coupling is introduced, the system enters a parity-time-broken regime in which the transparency ceases to be purely passive and becomes gain assisted, leading to asymmetric transmission with amplification on one side of the resonance and enhanced absorption on the other. By tuning the cavity detuning, we convert magnomechanical transparency into Fano-type line shapes with strongly non-Lorentzian phase dispersion and map their deformation into asymmetric, gain-assisted Fano ridges in the joint space of probe and magnon detunings. Finally, we analyze the associated group delay and show that both slow- and fast-light behavior can be widely tuned by varying the photon-magnon and magnomechanical couplings together with the non-Hermitian strength, highlighting parity-time-symmetric cavity magnomechanics as a promising platform for reconfigurable quantum signal processing and enhanced sensing. + oai:arXiv.org:2512.08612v1 quant-ph math-ph - math.FA math.MP - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Bernadette Lessel - - - Suppressing Fast Dipolar Noise in Solid-State Spin Qubits - https://arxiv.org/abs/2512.06948 - arXiv:2512.06948v1 Announce Type: new -Abstract: Spin qubit coherence is a fundamental resource for the realization of quantum technologies. For solid-state platforms, spin decoherence is dominated by the magneto-active environment in the lattice, limiting their applicability. While standard dynamical decoupling techniques, such as the Hahn echo, extend central spin coherence, they fail to suppress the fast noise arising from strong dipolar interactions within the bath. Here, we present a decoupling mechanism, Hybrid-LG, that suppresses intra-bath dipolar interactions -- thus, fast noise acting on spin qubits- and demonstrate its effectiveness in extending spin coherence through efficient in-house CCE simulations. Specifically, we investigate one of the most widely exploited solid-state quantum platforms: an ensemble of nitrogen-vacancy (NV) centers in diamond coupled to a large and dense bath of substitutional nitrogen paramagnetic impurities (P1 centers). Our results reveal at least a twofold enhancement in NV coherence time relative to standard techniques including P1 center driving, without requiring additional control power. - oai:arXiv.org:2512.06948v1 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + physics.optics + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Jaime Garc\'ia Oliv\'an, Ainitze Biteri-Uribarren, Oliver T. Whaites, Jorge Casanova + Cham Oumie, Wu-Ming Liu, Kashif Ammar Yasir - On possible extensions of quantum mechanics - https://arxiv.org/abs/2512.06964 - arXiv:2512.06964v1 Announce Type: new -Abstract: It was argued [1] that there can be no extension of quantum mechanics with improved predictive power on a measurement freely chosen, independently of any event that is not in its future light cone. The assumption of measurement choice was criticized [2] to be too strong to be physically necessary and extensions of quantum mechanics were shown [3] to be possible under a more relaxed measurement assumption. Here I point out an error in the criticism and observe that the actual mistake of the no-go theorem lies in an unwarranted assumption implicitly made in the proof of [1]. Hence, quantum mechanics is guaranteed to have the maximal predictive power only in situations of complete certainty and complete uncertainty about measurement outcomes. I then show that the measurement assumption can be further relaxed without affecting the conclusion on the predictive power of quantum mechanics versus alternative theories. I further study the optimal predicative improvement over quantum mechanics of local spin measurements on a pair of entangled qubits by any alternative theory and conjecture a strict upper bound. - oai:arXiv.org:2512.06964v1 + An Efficient Secret Communication Scheme for the Bosonic Wiretap Channel + https://arxiv.org/abs/2512.08623 + arXiv:2512.08623v1 Announce Type: new +Abstract: We propose a new secret communication scheme over the bosonic wiretap channel. It uses readily available hardware such as lasers and direct photodetectors. The scheme is based on randomness extractors, pulse-position modulation, and Reed-Solomon codes and is therefore computationally efficient. It is secure against an eavesdropper performing coherent joint measurements on the quantum states it observes. In the low-photon-flow limit, the scheme is asymptotically optimal and achieves the same dominant term as the secrecy capacity of the same channel. + oai:arXiv.org:2512.08623v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cs.CR + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Yiruo Lin + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1109/LCOMM.2025.3625640 + Esther H\"anggi, Iy\'an M\'endez Veiga, Ligong Wang - Quantum Correlation Assisted Cooling of Microwave Cavities Below the Ambient Temperature - https://arxiv.org/abs/2512.06996 - arXiv:2512.06996v1 Announce Type: new -Abstract: We develop a theoretical framework for cooling a microwave cavity mode using a Poisson stream of internally correlated pairs of two-level systems and analyze its performance under realistic dissipation. Starting from a Lindblad model of a phonon-tethered cavity interacting with sequentially injected atom pairs, we derive closed-form expressions for the steady-state cavity occupation and effective temperature. Two coupling geometries are examined: a one-atom configuration, where only one member of each pair interacts with the cavity, and a two-atom configuration, where both atoms couple collectively. The single-atom model enables cooling below the phonon bath but not below the reservoir temperature, whereas the two-atom scheme exhibits enhanced refrigeration - pair correlations modify the cavity's upward and downward transition rates so that the steady-state temperature can fall well below that of the reservoir for weak phonon damping. We map the parameter space including detuning, coupling strength, damping, and intra-pair exchange, identifying cooling valleys near resonance and the crossover between reservoir- and phonon-dominated regimes. The two-atom configuration thus realizes a genuine quantum-enhanced cooling mechanism absent in the single-atom case. We further outline an experimental implementation using two superconducting qubits repeatedly prepared, coupled, and reset inside a 3D cavity. Realistic reset and flux-tuning protocols support MHz-rate interaction cycles, enabling engineered reservoirs to impose cavity temperatures of 50-120 mK even when the cryostat is at ~1 K, offering a pathway to autonomous, on-chip refrigeration of microwave modes in scalable quantum hardware. - oai:arXiv.org:2512.06996v1 + Parity erasure: a foundational principle for indefinite causal order + https://arxiv.org/abs/2512.08635 + arXiv:2512.08635v1 Announce Type: new +Abstract: Processes with indefinite causal order can arise when quantum theory is locally valid. Here, we identify an information-theoretic principle, termed parity erasure, that completely characterizes such processes. Our characterization does not rely on the formalism of quantum theory itself, but instead is derived from a set of axioms for general operational probabilistic theories, and thus holds also for a large class of theories beyond quantum theory. This informational approach reveals a fundamental property of information exchange in scenarios with indefinite causal structure. + oai:arXiv.org:2512.08635v1 quant-ph - cond-mat.mes-hall - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daryoosh Vashaee, Jahanfar Abouie + Zixuan Liu, Ognyan Oreshkov - Bohmian Trajectories Within Hilbert Space Based Quantum Mechanics. Solution of the Measurement Problem - https://arxiv.org/abs/2512.07007 - arXiv:2512.07007v1 Announce Type: new -Abstract: de Broglie-Bohm theory (dBBT), treating quantum particles as point objects moving along well defined (Bohmian) trajectories, offers an appealing solution of the measurement problem in quantum mechanics; it has, however, problems relating to spin, relativity and lack of proper integration with the Hilbert space based framework. In this work, we present a consistent formalism which has the traditional state-observable framework integrated with the desirable features of dBBT. We adopt ensemble interpretation for the Schrodinger wave function $\psi$. Given a Schrodinger wave function $\psi$, we use its value $\psi_0$ at some fixed time (say, $t = 0$) to define the probability measure $|\psi_0|^2 {\rm d}x$ on the system configuration space $M$ ($=\mathbb{R}^n$). On the resulting probability space $\mathcal{M}_0$, we introduce a stochastic process $\xi(t)$ corresponding to the Heisenberg position operator $X_H(t)$ such that, in the Heisenberg state $|\psi_h\rangle$ corresponding to $\psi_0$, the expectation value of $X_H(t)$ equals that of $\xi(t)$ in $\mathcal{M}_0$. This condition leads to the de Broglie-Bohm guidance equation for the sample paths of the process $\xi(t)$ which are, therefore, Bohmian trajectories supposedly representing time-evolutions of individual members of the $\psi_0$-ensemble. Stochastic processes and Bohmian trajectories corresponding to observables with discrete eigenvalues (in particular spin) are treated by extending the configuration space to the spectral space of the commutative algebra obtained by adding appropriate discrete observables to the position observables. Pauli's equation is treated as an example. A straightforward derivation of von Neumann's projection rule employing the Schrodinger-Bohm evolution of individual systems along their Bohmian trajectories is given. Some comments on the potential application of the formalism developed here to quantum mechanics of the universe are included. - oai:arXiv.org:2512.07007v1 + Strain sensitivity enhancement in a Grover-Michelson interferometer + https://arxiv.org/abs/2512.08638 + arXiv:2512.08638v1 Announce Type: new +Abstract: The Michelson interferometric phase detection resolution can be enhanced by replacing conventional beam splitters with novel directionally unbiased four-port scatterers, such as Grover coins. We present a quantitative analysis of the noise-to-signal ratio of sideband frequencies generated by gravitational wave-induced phase perturbations in a Grover-Michelson interferometer (GMI). We discuss the principles of GMI signal enhancement and demonstrate how combining this configuration with additional light-recycling arrangements further enhances the performance. + oai:arXiv.org:2512.08638v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + physics.optics + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Tulsi Dass + 10.1103/8h71-w8tt + Manni, A., Schwarze, C., Simon, D., Ndao, A., & Sergienko, A. (2025). Strain sensitivity enhancement in a Grover-Michelson interferometer. Phys. Rev. D, 112, 122002 + Anthony D. Manni, Christopher R. Schwarze, David S. Simon, Abdoulaye Ndao, Alexander V. Sergienko - From Quantum Chaos to Classical Chaos via Gain-Induced Measurement Dynamics in a Photon Gas - https://arxiv.org/abs/2512.07045 - arXiv:2512.07045v1 Announce Type: new -Abstract: How classical chaos emerges from quantum mechanics remains a central open question, as the unitary evolution of isolated quantum systems forbids exponential sensitivity to initial conditions. A key insight is that this quantum-classical link is provided by measurement processes. In this work, we identify gain competition in a chaotic photon gas as an operational quantum measurement that selects single motional modes from an initial superposition through stochastic, nonlinear amplification. We show that this mechanism naturally gives rise to classical chaotic behavior, most notably sensitivity to initial conditions. Our results provide a concrete physical mechanism for the quantum-classical transition in a chaotic system and demonstrate that essential aspects of quantum measurement-state projection, Born-rule-like selection, and irreversibility-can naturally emerge from intrinsic gain dynamics. - oai:arXiv.org:2512.07045v1 + Quantum Brownian Motion as a Classical Stochastic Process in Phase Space + https://arxiv.org/abs/2512.08641 + arXiv:2512.08641v1 Announce Type: new +Abstract: We establish that the exact quantum dynamics of a Brownian particle in the Caldeira-Leggett model can be mapped, at any temperature, onto a classical, non-Markovian stochastic process in phase space. Starting from a correlated thermal equilibrium state between the particle and bath, we prove that this correspondence is exact for quadratic potentials under arbitrary quantum state preparations of the particle itself. For more general, smooth potentials, we identify and exploit a natural small parameter: the density matrix becomes strongly quasidiagonal in the coordinate representation, with its off-diagonal width shrinking as the bath's spectral cutoff increases, providing a controlled parameter for accurate approximation. The framework is fully general: arbitrary initial quantum states-including highly non-classical superpositions-are incorporated via their Wigner functions, which serve as statistical weights for trajectory ensembles. Furthermore, the formalism naturally accommodates external manipulations and measurements modeled by preparation functions acting at arbitrary times, enabling the simulation of complex driven-dissipative quantum protocols. + oai:arXiv.org:2512.08641v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Violetta Sharoglazova, Marius Puplauskis, Lotte Hof, Jan Klaers + http://creativecommons.org/licenses/by/4.0/ + Dmitriy Kondaurov, Evgeny Polyakov - The uncharted space of non-Hermitian solutions to the Hartree-Fock and Kohn-Sham equations - https://arxiv.org/abs/2512.07048 - arXiv:2512.07048v1 Announce Type: new -Abstract: Many problems in physical chemistry involve systems that are coupled to an environment, such as a molecule interacting with an adjacent surface, possibly resulting in meta-stable molecular states where electron density is transferred to the surface. Such systems can be described by non-Hermitian quantum mechanics (NHQM), where the Hamiltonian includes dissipative terms. Within NHQM, one can also formulate the Hartree-Fock (HF) and Kohn-Sham (KS) methods and, as in the conventional theory, an effective independent-particle picture is employed. The crucial observation of the present work is that even for systems that are not coupled to an environment, in the HF or KS equation a single electron is coupled to a bath of the remaining electrons which can act as an environment, opening up the possibility for the exchange of current density between the one-electron and the remaining N-1 electron system. The corresponding self-consistent states represent a new uncharted space of solutions to the HF and KS equations. We show that the additional solutions can have a physical interpretation and thus extend the range of problems HF and KS can be applied to. If open-system HF and KS calculations are performed, the new class of solutions is always encountered but this has also not been noted previously. - oai:arXiv.org:2512.07048v1 + Perfect continuous-variable quantum microcombs + https://arxiv.org/abs/2512.08650 + arXiv:2512.08650v1 Announce Type: new +Abstract: Quantum microcombs generated in high-Q microresonators provide compact, multiplexed sources of entangled modes for continuous-variable (CV) quantum information processing. While deterministic generation of CV states via Kerr-induced two-mode squeezing has been demonstrated, achieving spectrally uniform squeezing remains challenging because of asymmetry and anomalies in the dispersion profile. Here we overcome these limitations by combining a microresonator with an engineered mode spectrum and optimized pump conditions. We realize a CV quantum microcomb comprising 14 independent two-mode squeezed states, each exhibiting more than 4 dB of raw squeezing (up to 4.3 dB) across a 0.7 THz bandwidth. This uniform, high-performance quantum resource represents a key step toward scalable, integrated CV quantum technologies operating beyond classical limits. + oai:arXiv.org:2512.08650v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + physics.optics + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1063/5.0272598 - J. Chem. Phys. 163, 214105 (2025) - Matthias Ernzerhof, Mohamed Loutis, Pierre-Olivier Roy, Didier Mayou + Kangkang Li, Yue Wang, Ze Wang, Xin Zhou, Jincheng Li, Yinke Cheng, Binyan Wu, Qihuang Gong, Bei-Bei Li, Qi-Fan Yang - Timing quantum emission: coherence, superradiance, and entanglement in order - https://arxiv.org/abs/2512.07055 - arXiv:2512.07055v1 Announce Type: new -Abstract: We investigate the short-term temporal dynamics of superradiance in closely spaced quantum emitters. Building on Dicke's 1954 framework, we analyze the sequential emergence of coherence, superradiance, and entanglement, revealing a distinct temporal hierarchy in their extremal values: relative coherence develops first, followed by the peak of correlated emission, then minimal entanglement, and finally correlated dephasing. These findings suggest that enhanced relative coherence initiates correlated emission and when correlated dephasing is negligible, entanglement and correlated emission become tightly linked in time. - oai:arXiv.org:2512.07055v1 + Spectroscopic readout of chiral photonic topology in a single-cavity spin-orbit-coupled Bose-Einstein condensate + https://arxiv.org/abs/2512.08662 + arXiv:2512.08662v1 Announce Type: new +Abstract: Topological photonic phases are typically identified through band reconstruction, steady-state transmission, or real-space imaging of edge modes. In this work, we present a framework for spectroscopic readout of chiral photonic topology in a single driven optical cavity containing a spin-orbit-coupled Bose-Einstein condensate. We demonstrate that the cavity transmission power spectral density provides a direct and measurable proxy for a momentum- and frequency-resolved photonic Chern marker, enabling topological characteristics to be inferred from spectral data without the need for bulk-band tomography. In the loss-dominated regime, where cavity decay exceeds atomic dissipation, the power spectral density exhibits Dirac-like gapped hybrid modes with a vanishing Chern marker, indicating a trivial phase. When the dissipation imbalance is reversed, a bright, gap-spanning spectral ridge emerges, co-localized with peaks in both the Chern marker and Berry curvature. The complex spectrum reveals parity-time symmetric coalescences and gain-loss bifurcations, marking exceptional points and enabling chiral, gap-traversing transport. By linking noise spectroscopy to geometric and non-Hermitian topology in a minimal cavity-QED architecture, this work provides a framework for spectroscopic detection of topological order in driven quantum systems. This approach offers a pathway to compact, tunable topological photonics across a broad range of light-matter platforms, providing a method for the study and control of topological phases in hybrid quantum systems. + oai:arXiv.org:2512.08662v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.quant-gas + physics.app-ph + physics.optics + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Nur Fadhillah Binti Rahimi, Norman Koo Tze Wei, Daniel Schumayer, Christopher Gies, Leong Chuan Kwek, David. A. W. Hutchinson + Kashif Ammar Yasir, Gao Xianlong - Beam search decoder for quantum LDPC codes - https://arxiv.org/abs/2512.07057 - arXiv:2512.07057v1 Announce Type: new -Abstract: We propose a decoder for quantum low density parity check (LDPC) codes based on a beam search heuristic guided by belief propagation (BP). Our beam search decoder applies to all quantum LDPC codes and achieves different speed-accuracy tradeoffs by tuning its parameters such as the beam width. We perform numerical simulations under circuit level noise for the $[[144, 12, 12]]$ bivariate bicycle (BB) code at noise rate $p=10^{-3}$ to estimate the logical error rate and the 99.9 percentile runtime and we compare with the BP-OSD decoder which has been the default quantum LDPC decoder for the past six years. A variant of our beam search decoder with a beam width of 64 achieves a $17\times$ reduction in logical error rate. With a beam width of 8, we reach the same logical error rate as BP-OSD with a $26.2\times$ reduction in the 99.9 percentile runtime. We identify the beam search decoder with beam width of 32 as a promising candidate for trapped ion architectures because it achieves a $5.6\times$ reduction in logical error rate with a 99.9 percentile runtime per syndrome extraction round below 1ms at $p=5 \times10^{-4}$. Remarkably, this is achieved in software on a single core, without any parallelization or specialized hardware (FPGA, ASIC), suggesting one might only need three 32-core CPUs to decode a trapped ion quantum computer with 1000 logical qubits. - oai:arXiv.org:2512.07057v1 + A Unified Framework for Optimizing Uniformly Controlled Structures in Quantum Circuits + https://arxiv.org/abs/2512.08675 + arXiv:2512.08675v1 Announce Type: new +Abstract: Quantum unitaries of the form ${\Sigma_{c}\ket{c}\bra{c}\otimes U_{c}}$ are ubiquitous in quantum algorithms. This class encompasses not only standard uniformly controlled gates (UCGs) but also a wide range of circuits with uniformly controlled structures. However, their circuit-depth and gate-count complexities have not been systematically analyzed within a unified framework. In this work, we study the general decomposition problem for UCG and UCG-like structure. We then introduce the restricted Uniformly Controlled Gates (rUCGs) as a unified algebraic model, defined by a 2-divisible Abelian group that models the controlled gate set. This model captures uniformly controlled rotations, multi-qubit uniformly controlled gates, and diagonal unitaries. Furthermore, this model also naturally incorporates k-sparse version (k-rUCGs), where only a subset of control qubits participate in each multi-qubit gate. Building on this algebraic model, we develop a general framework. For an n-control rUCG, the framework reduce the gate complexity from ${O(n2^n)}$ to ${O(2^n})$ and the circuit depth from ${O(2^n\log n)}$ to ${O(2^n\log n/n)}$. The framework further provides systematic size and depth bounds for k-rUCGs by exploiting sparsity in the control space, with same optimization coefficient as rUCG, respectively. Empirical evaluations on representative QAOA circuits and quantum state preparation both confirm reductions in depth and size. Crucially, these results highlight that the rUCG model and its associated decomposition framework unify circuits previously considered structurally distinct under a single, asymptotically optimal synthesis paradigm. + oai:arXiv.org:2512.08675v1 quant-ph - cs.IT - math.IT - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Min Ye, Dave Wecker, Nicolas Delfosse + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Chengzhuo Xu, Xiao Chen, Xi Li, Zhihao Liu, Zhigang Li - Hidden Structural Variants in ALD NbN Superconducting Trilayers Revealed by Atomistic Analysis - https://arxiv.org/abs/2512.07095 - arXiv:2512.07095v1 Announce Type: new -Abstract: Microscopic inhomogeneity within superconducting films is a critical bottleneck hindering the performance and scalability of quantum circuits. All-nitride Josephson Junctions (JJs) have attracted substantial attention for their potential to provide enhanced coherence times and enable higher temperature operation. However, their performance is often limited by local variations caused by polymorphism, impurities, and interface quality. This work diagnoses atomic-scale limitations preventing superconducting NbN/AlN/NbN JJs from reaching their full potential. Electrical measurements reveal suppressed critical current density and soft onset of quasiparticle current. However, inverse proportionality between resistance and junction area confirms homogenous barrier thickness. This isolates structural and chemical variations in electrodes and barrier as the source of performance limitation. The observed characteristics are attributed to complex materials problems: NbN polymorphism, phase coexistence, and oxygen impurities. Using advanced microscopy and machine learning integrated approach, nanoscale inclusions of epsilon-Nb2N2 are found to coexist within dominant delta-NbN electrodes. DC performance of JJs may be affected by these defects, leading to unresolved supercurrent and soft transition to normal state. By identifying specific atomic scale defects, tracing its origin to initial film nucleation, and linking to its detrimental electrical signature, this work establishes a material-to-device correlation and provides targeted strategy for phase engineering towards reproducible, high coherence and scalable quantum devices. - oai:arXiv.org:2512.07095v1 + Non-Hermitian symmetry breaking and Lee-Yang theory for quantum XYZ and clock models + https://arxiv.org/abs/2512.08687 + arXiv:2512.08687v1 Announce Type: new +Abstract: Lee-Yang theory offers a unifying framework for understanding classical phase transitions and dynamical quantum phase transitions through the analysis of partition functions and Loschmidt echoes. Recently, this framework is extended to characterize quantum phase transitions in arXiv:2509.20258 by introducing the concepts of non-Hermitian symmetry breaking and fidelity zeros. Here, we generalize the theory by studying a broad class of quantum models, including the XY model, the XXZ model, the XYZ model, and the $\mathbb{Z}_3$ clock model in one dimension, subject to complex external magnetic field. For the XY, XXZ and XYZ models, we find that the complex field breaks parity symmetry and induces oscillations of the ground state between the two parity sectors, giving rise to fidelity zeros within the ordered phases. For the $\mathbb{Z}_3$ clock model, the complex field splits the real part of the ground-state energy between the neutral sector ($q=0$) and the charged sectors ($q=1,2$), while preserving the degeneracy within the charged sector. Fidelity zeros arise only after projecting out one of the charged sectors, and the finite-size scaling of these zeros produces critical exponents fully consistent with analytical predictions. + oai:arXiv.org:2512.08687v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Prachi Garg, Danqing Wang, Hong X. Tang, Baishakhi Mazumder + Tian-Yi Gu, Gaoyong Sun - Wigner's Frame - https://arxiv.org/abs/2512.07101 - arXiv:2512.07101v1 Announce Type: new -Abstract: This article suggests that thinking about the role of reference frames can provide new insight into Extended Wigner's Friend scenarios. This involves appealing to symmetries to make a principled distinction between properties of a system which are meaningful only relative to an external reference system and properties which are meaningful without further relativization. Thus we may propose that there are always well-defined facts about what observers have observed, but there are not necessarily well-defined facts about the relations between their reference frames, so there will not always exist a joint distribution over their outcomes which can meaningfully be compared to the predictions of quantum mechanics. In addition, this approach also offers a general argument against the idea that there should be a regress of relativization. - oai:arXiv.org:2512.07101v1 + Geometry-driven transitions in sparse long-range spin models with cold atoms + https://arxiv.org/abs/2512.08709 + arXiv:2512.08709v1 Announce Type: new +Abstract: We explore the influence of geometry in the critical behavior of sparse long-range spin models. We examine a model with interactions that can be continuously tuned to induce distinct changes in the metric, topology, and dimensionality of the coupling graph. This underlying geometry acts as the driver of criticality, with structural changes in the graph coinciding with and dictating the phase boundaries. We further discuss how this framework connects naturally to realizations in tweezer arrays with Rydberg excitations. In certain cases, the effective geometry can be incorporated in the layout of atoms in tweezers to realize phase transitions that preserve universal features, simplifying their implementation in near-term experiments. + oai:arXiv.org:2512.08709v1 quant-ph - physics.hist-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.quant-gas + cond-mat.stat-mech + Wed, 10 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Emily Adlam + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Alex Gunning, Aydin Deger, Sridevi Kuriyattil, Andrew J. Daley - Scheduling in Quantum Satellite Networks: Fairness and Performance Optimization - https://arxiv.org/abs/2512.07108 - arXiv:2512.07108v1 Announce Type: new -Abstract: Quantum satellite networks offer a promising solution for achieving long-distance quantum communication by enabling entanglement distribution across global scales. This work formulates and solves the quantum satellite network scheduling problem by optimizing satellite-to-ground station pair assignments under realistic system and environmental constraints. Our framework accounts for limited satellite and ground station resources, fairness, entanglement fidelity thresholds, and real world non-idealities including atmospheric losses, weather and background noise. In addition, we incorporate the complexities of multi-satellite relays enabled via inter-satellite links. We propose an integer linear programming (ILP) based optimization framework that supports multiple scheduling objectives, allowing us to analyze tradeoffs between maximizing total entanglement distribution rate and ensuring fairness across ground station pairs. Our framework can also be used as a benchmark tool to measure the performance of other potential transmission scheduling policies. - oai:arXiv.org:2512.07108v1 + Non-abelian quantum double models from iterated gauging + https://arxiv.org/abs/2512.08749 + arXiv:2512.08749v1 Announce Type: new +Abstract: We reconstruct all (2+1)D quantum double models of finite groups from their boundary symmetries through the repeated application of a gauging procedure, extending the existing construction for abelian groups. We employ the recently proposed categorical gauging framework, based on matrix product operators (MPOs), to derive the appropriate gauging procedure for the $\mathsf{Rep}\, G$ symmetries appearing in our construction and give an explicit description of the dual emergent $G$ symmetry, which is our main technical contribution. Furthermore, we relate the possible gapped boundaries of the quantum double models to the quantum phases of the one-dimensional input state to the iterated gauging procedure. Finally, we propose a gauging procedure for 1-form $\mathsf{Rep}\, G$ symmetries on a two-dimensional lattice and use it to extend our results to the construction of (3+1)D quantum doubles models through the iterative gauging of (2+1)-dimensional symmetries. + oai:arXiv.org:2512.08749v1 quant-ph - cs.PF - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.str-el + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Ashutosh Jayant Dikshit, Naga Lakshmi Anipeddi, Prajit Dhara, Saikat Guha, Deirdre Kilbane, Leandros Tassiulas, Don Towsley, Nitish K. Panigrahy + David Blanik, Jos\'e Garre-Rubio - Digital-Analog-Digital Quantum Supremacy - https://arxiv.org/abs/2512.07127 - arXiv:2512.07127v1 Announce Type: new -Abstract: Quantum supremacy has been explored extensively in gate-model settings. Here, we introduce a quantum-supremacy framework for a hybrid digital-analog-digital quantum computing (DADQC) model. We consider a device that applies an initial layer of single-qubit gates, a single transverse-field Ising analog block, and a final single-qubit layer before $Z$-basis readout. The analog block approximates $Z$-diagonal Ising evolution, and we prove that the resulting output distribution is within constant total-variation (TV) distance of an Instantaneous Quantum Polynomial-time (IQP) circuit. Our bounds and constructions are established for fully connected as well as bounded-degree hardware graphs, matching a variety of architectures, including trapped-ion, neutral atom, and superconducting platforms. Assuming anticoncentration (which we prove for all-to-all hardware graphs and conjecture for bounded-degree hardware graphs) and an average-case hardness conjecture for the associated complex-temperature Ising partition functions, standard reductions imply that any efficient classical sampler achieving constant TV error collapses the polynomial hierarchy. Our results imply that quantum-supremacy tests are possible on today's quantum annealers, as well as other devices capable of hybrid digital-analog quantum evolution. - oai:arXiv.org:2512.07127v1 + Floquet Topological Frequency-Converting Amplifier + https://arxiv.org/abs/2512.08880 + arXiv:2512.08880v1 Announce Type: new +Abstract: We introduce a driven-dissipative Floquet model in which a single harmonic oscillator with modulated frequency and decay realizes a non-Hermitian synthetic lattice with an effective electric field gradient in frequency space. Using the Floquet-Green's function and its doubled-space representation, we identify a topological regime that supports directional amplification and frequency conversion, accurately captured by a local winding number. The underlying mode structure is well described by a Jackiw-Rebbi-like continuum theory with Dirac cones and solitonic zero modes in synthetic frequency. Our results establish a simple and experimentally feasible route to non-Hermitian topological amplification, naturally implementable in current quantum technologies such as superconducting circuits. + oai:arXiv.org:2512.08880v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Daniel Lidar + Adrian Parra-Rodriguez, Miguel Clavero-Rubio, Philippe Gigon, Tom\'as Ramos, \'Alvaro G\'omez-Le\'on, Diego Porras - A manufacturable surface code architecture for spin qubits with fast transversal logic - https://arxiv.org/abs/2512.07131 - arXiv:2512.07131v1 Announce Type: new -Abstract: Spin qubits in silicon quantum dot arrays are a promising quantum computation platform for long-term scalability due to their small qubit footprint and compatibility with advanced semiconductor manufacturing. However, spin qubit devices face a key architectural bottleneck: the large physical footprint of readout components relative to qubits prevents a dense layout where all qubits can be measured simultaneously, complicating the implementation of quantum error correction. This challenge is offset by the platform's unique rapid shuttling capability, which can be used to transport qubits to distant readout ports. In this work, we explore the design constraints and capabilities of spin qubits in silicon and propose the SNAQ (Shuttling-capable Narrow Array of spin Qubits) surface code architecture, which relaxes the 1:1 readout-to-qubit assumption by leveraging spin shuttling to time-multiplex ancilla qubit initialization and readout. Our analysis shows that, given sufficiently high (experimentally demonstrated) qubit coherence times, SNAQ delivers an orders-of-magnitude reduction in chip area per logical qubit. Additionally, by using a denser grid of physical qubits, SNAQ enables fast transversal logic for short-distance logical operations, achieving 4.0-22.3x improvement in local logical clock speed while still supporting global operations via lattice surgery. This translates to a 57-60% reduction in spacetime cost of 15-to-1 magic state distillation, a key fault-tolerant subroutine. Our work pinpoints critical hardware metrics and provides a compelling path toward high-performance fault-tolerant computation on near-term-manufacturable spin qubit arrays. - oai:arXiv.org:2512.07131v1 + Emergent Non-Markovianity in Logical Qubit Dynamics + https://arxiv.org/abs/2512.08893 + arXiv:2512.08893v1 Announce Type: new +Abstract: Logical qubits encoded in quantum error correcting codes can exhibit non-Markovian dynamical evolution, even when the underlying physical noise is Markovian. To understand this emergent non-Markovianity, we define a Markovianity condition appropriate to logical gate operations, and study it by relating logical operations to their physical implementation (operations on the data qubits into which the logical qubit is encoded). We apply our analysis to small quantum codes, and show that they exhibit non-Markovian dynamics even for very simple physical noise models. We show that non-Markovianity can emerge from Markovian physical operations if (and only if) the physical qubits are not necessarily returned to the code subspace after every round of QEC. In this situation, the syndrome qubits can act as a memory, mediating time correlations and enabling violation of the Markov condition. We quantify the emergent non-Markovianity in simple examples, and propose sufficient conditions for reliable use of gate-based characterization techniques like gate set tomography in early fault-tolerant quantum devices. + oai:arXiv.org:2512.08893v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jason D. Chadwick, Willers Yang, Joshua Viszlai, Frederic T. Chong - - - Beyond real: Investigating the role of complex numbers in self-testing - https://arxiv.org/abs/2512.07160 - arXiv:2512.07160v1 Announce Type: new -Abstract: We investigate complex self-testing, a generalization of standard self-testing that accounts for quantum strategies whose statistics is indistinguishable from their complex conjugate's. We show that many structural results from standard self-testing extend to the complex setting, including lifting of common assumptions. Our main result is an operator-algebraic characterization: complex self-testing is equivalent to uniqueness of the real parts of higher moments, leading to a basis-independent formulation in terms of real C* algebras. This leads to a classification of non-local strategies, and a tight boundary where standard self-testing do not apply and complex self-testing is necessary. We further construct a strategy involving quaternions, establishing the first standard self-test for genuinely complex strategy. Our work clarifies the structure of complex self-testing and highlights the subtle role of complex numbers in bipartite Bell non-locality. - oai:arXiv.org:2512.07160v1 - quant-ph - math.OA - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Ranyiliu Chen, Laura Man\v{c}inska, Jurij Vol\v{c}i\v{c} + Jalan A. Ziyad, Robin Blume-Kohout, Kenneth Rudinger - A versatile coherent Ising computing platform - https://arxiv.org/abs/2512.07182 - arXiv:2512.07182v1 Announce Type: new -Abstract: Coherent Ising Machines (CIMs) have emerged as a hybrid form of quantum computing devices designed to solve NP-complete problems, offering an exciting opportunity for discovering optimal solutions. Despite challenges such as susceptibility to noise-induced local minima, we achieved notable advantages in improving the computational accuracy and stability of CIMs. We conducted a successful experimental demonstration of CIM via femto-second laser pumping that integrates optimization strategies across optical and structural dimensions, resulting in significant performance enhancements. The results are particularly promising. An average success rate of 55% was achieved to identify optimal solutions within a Mobius Ladder graph comprising 100 vertices. Compared with other alternatives, the femto-second pulse results in significantly higher peak power, leading to more pronounced quantum effects and lower pump power in optical fiber based CIMs. In addition, we have maintained an impressive success rate for a continuous period of 8 hours, emphasizing the practical applicability of CIMs in real-world scenarios. Furthermore, our research extends to the application of these principles in practical applications such as molecular docking and credit scoring. The results presented substantiate the theoretical promise of CIMs, paving the way for their integration into large-scale practical applications. - oai:arXiv.org:2512.07182v1 + Deterministic randomness extraction for semi-device-independent quantum random number generation + https://arxiv.org/abs/2512.08900 + arXiv:2512.08900v1 Announce Type: new +Abstract: It is a well-known fact in classical information theory that no deterministic procedure can extract close-to-ideal randomness from an arbitrary entropy source. On the other hand, if additional knowledge about the source is available -- e.g., that it is a sequence of independent Bernoulli trials -- then deterministic extractors do exist. For quantum entropy sources, where in addition to classical random variables we consider quantum side information, the use of extra knowledge about their structure was pioneered in a recent publication [C. Foreman and L. Masanes, Quantum 9, 1654 (2025)]. In that work, the authors provide deterministic extractors for device-independent randomness generation with memoryless devices achieving a sufficiently high CHSH score. In this work, we extend their construction to the prepare-and-measure scenario. Specifically, we prove that the considered functions are also extractors for memoryless devices in a semi-device-independent setting under an overlap assumption on the prepared quantum states. We then simulate the resulting randomness generation protocol on a novel and experimentally relevant family of behaviors, observing positive key rates already for $7\times 10^3$ rounds. + oai:arXiv.org:2512.08900v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Hai Wei, Chengjun Ai, Putuo Guo, Bingjie Jia, Lixin Yuan, Hanquan Song, Shaobo Chen, Chongyu Cao, Jie Wu, Chao Ju, Yin Ma, Jintao Fan, Minglie Hu, Chuan Wang, Kai Wen + Pablo Tikas Pueyo, Tom\'as Fern\'andez Martos, Gabriel Senno - Non-Hermitian Bose-Hubbard-like quantum models - https://arxiv.org/abs/2512.07250 - arXiv:2512.07250v1 Announce Type: new -Abstract: Among all of the non-Hermitian large-tridiagonal-matrix quantum Hamiltonians we choose a subclass with the structure resembling the ``benchmark'' realistic Bose-Hubbard model. We demonstrate that this choice can be declared user-friendly in the sense that the underlying singular values can be specified via a ``Hermitized'' Schr\"{o}dinger-like equation. In particular, the related ``Hermitized'' Green's functions is shown given the two alternative compact and numerically efficient matrix continued fraction forms. - oai:arXiv.org:2512.07250v1 + SAQ: Stabilizer-Aware Quantum Error Correction Decoder + https://arxiv.org/abs/2512.08914 + arXiv:2512.08914v1 Announce Type: new +Abstract: Quantum Error Correction (QEC) decoding faces a fundamental accuracy-efficiency tradeoff. Classical methods like Minimum Weight Perfect Matching (MWPM) exhibit variable performance across noise models and suffer from polynomial complexity, while tensor network decoders achieve high accuracy but at prohibitively high computational cost. Recent neural decoders reduce complexity but lack the accuracy needed to compete with computationally expensive classical methods. We introduce SAQ-Decoder, a unified framework combining transformer-based learning with constraint aware post-processing that achieves both near Maximum Likelihood (ML) accuracy and linear computational scalability with respect to the syndrome size. Our approach combines a dual-stream transformer architecture that processes syndromes and logical information with asymmetric attention patterns, and a novel differentiable logical loss that directly optimizes Logical Error Rates (LER) through smooth approximations over finite fields. SAQ-Decoder achieves near-optimal performance, with error thresholds of 10.99% (independent noise) and 18.6% (depolarizing noise) on toric codes that approach the ML bounds of 11.0% and 18.9% while outperforming existing neural and classical baselines in accuracy, complexity, and parameter efficiency. Our findings establish that learned decoders can simultaneously achieve competitive decoding accuracy and computational efficiency, addressing key requirements for practical fault-tolerant quantum computing systems. + oai:arXiv.org:2512.08914v1 quant-ph - cs.NA - math.NA - Tue, 09 Dec 2025 00:00:00 -0500 + cs.AI + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1088/1742-6596/3152/1/012023 - J. Phys.: Conf. Ser. 3152 (2025) 012023 - Miloslav Znojil + David Zenati, Eliya Nachmani - Quantum geometrical effects in non-Hermitian systems - https://arxiv.org/abs/2512.07264 - arXiv:2512.07264v1 Announce Type: new -Abstract: We explore the relation between quantum geometry in non-Hermitian systems and physically measurable phenomena. We highlight various situations in which the behavior of a non-Hermitian system is best understood in terms of quantum geometry, namely the notion of adiabatic potentials in non-Hermitian systems and the localization of Wannier states in periodic non-Hermitian systems. Further, we show that the non-Hermitian quantum metric appears in the response of the system upon time-periodic modulation, which one can use to experimentally measure the non-Hermitian quantum metric. We validate our results by providing numerical simulations of concrete exemplary systems. - oai:arXiv.org:2512.07264v1 + Autonomous multi-ion optical clock with on-chip integrated photonic light delivery + https://arxiv.org/abs/2512.08921 + arXiv:2512.08921v1 Announce Type: new +Abstract: Integrated photonics in trapped-ion systems are critical for the realization of applications such as portable optical atomic clocks and scalable quantum computers. However, system-level integration of all required functionalities remains a key challenge. In this work, we demonstrate an autonomously operating optical clock having a short-term frequency instability of $3.14(5)\times 10^{-14} / \sqrt{\tau}$ using an ensemble of four \ybion ions trapped in a multi-site surface-electrode trap at room temperature. All clock operations are performed with light delivered via on-chip waveguides. We showcase the system's resilience through sustained, autonomous operation featuring automated ion shuttling and reloading to mitigate ion loss during interleaved clock measurements. This work paves the way beyond component-level functionality to establish a viable and robust architecture for the next generation of portable, multi-ion quantum sensors and computers. + oai:arXiv.org:2512.08921v1 quant-ph - cond-mat.mes-hall - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Anton Montag, Tomoki Ozawa + Tharon D. Morrison, Joonhyuk Kwon, Matthew A. Delaney, David R. Leibrandt, Daniel Stick, Hayden J. McGuinness - Simulating general noise nearly as cheaply as Pauli noise - https://arxiv.org/abs/2512.07304 - arXiv:2512.07304v1 Announce Type: new -Abstract: Stabilizer simulation of Clifford quantum circuits - error-correction circuits, Clifford subroutines, etc. - on classical computers has played a central role in our understanding of circuit performance. The stabilizer description, however, restricts the accessible noise one can incorporate into the simulation to Pauli-type noise. More general noise, including coherent errors, may have more severe impact on circuit performance than Pauli noise; yet, such general noise have been difficult to access, much less investigate fully, in numerical simulations. Here, through the use of stratified importance sampling, we show how general noise can be simulated within the stabilizer formalism in reasonable time, with non-unitary noise being nearly as cheap as Pauli noise. Unitary (or coherent) noise can require an order of magnitude more time for the simulation, but nevertheless completes in very reasonable times, a drastic improvement over past approaches that typically fail to converge altogether. Our work thus enables detailed beyond-Pauli understanding of circuit performance in the presence of real device noise, which is rarely Pauli in nature. Among other examples, we present direct simulation results for the performance of the popular rotated planar surface codes under circuit-level general noise, previously available only in limited situations and/or through mappings to efficiently simulatable physical models. - oai:arXiv.org:2512.07304v1 + Vortex leapfrogging and superfluid dissipation mechanisms in a fluid of light + https://arxiv.org/abs/2512.07935 + arXiv:2512.07935v1 Announce Type: cross +Abstract: We report the experimental observation of vortex leapfrogging in a two-dimensional fluid of light. By imprinting two vortex-antivortex pairs and tracking their real-time evolution through phase-resolved imaging, we observe a dynamics that is accurately described by a point-vortex model with an outward background flow. By precisely controlling the initial vortex separation, we identify configurations in which leapfrogging breaks down and determine the corresponding dissipation mechanisms. The first originates from phase-slip events occurring at large injected velocities. The second arises when the injection of multi-charged vortices leads to the formation of a dispersive shock wave which acts as a continuous source of phase slippage. These mechanisms advance our understanding of vortex dynamics and dissipation in superfluids. + oai:arXiv.org:2512.07935v1 + cond-mat.quant-gas + physics.flu-dyn quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - Mark Myers II, Mariesa H. Teo, Rajesh Mishra, Jing Hao Chai, Hui Khoon Ng + Myrann Baker-Rasooli, Nathan du Toit, Nicolas Pavloff, Quentin Glorieux - Single-cell identification with quantum-enhanced nuclear magnetic resonance - https://arxiv.org/abs/2512.07307 - arXiv:2512.07307v1 Announce Type: new -Abstract: Identification of individual cells within heterogeneous populations is essential for biomedical research and clinical diagnostics. Conventional labeling-based sorting methods, such as fluorescence-activated cell sorting and magnetic-activated cell sorting, enable precise sorting when reliable markers are available. However, their applicability is limited in cells lacking defined markers or sensitive to labeling, as labeling can compromise cellular viability and function. We present a single-cell identification approach using quantum-enhanced NMR with diamond nitrogen-vacancy centers for label-free detection of intracellular proton ($^1$H) signals. Using this method, we distinguish two human tumor cell lines by their proton spin-lattice ($T_1$) relaxation times, which serve as a cell-intrinsic physicochemical signature. It lays the groundwork for label-free sorting applications in rare cell analysis, personalized medicine, and single-cell diagnostics. - oai:arXiv.org:2512.07307v1 + Strong-field regime within effective field theory + https://arxiv.org/abs/2512.07958 + arXiv:2512.07958v1 Announce Type: cross +Abstract: Building upon the Covariant Derivative Expansion, we develop a method to compute effective actions that is able to capture non-perturbative effects induced by strong background fields. We demonstrate the method in scalar QED, by deriving the full second-derivative corrections to the scalar Heisenberg--Euler effective action. The corresponding result is interpreted as an effective field theory with three characteristic scales, two of which are large (mass and field strength) in comparison with the remaining one (derivatives of the field). As an application, we show that, at this order, the transseries structure of the Schwinger pair production rate is preserved, even if the involved coefficients are modified. Our analysis also helps clarify recent disagreements concerning the coefficients of this effective action. + oai:arXiv.org:2512.07958v1 + hep-th + hep-ph quant-ph - physics.bio-ph - physics.med-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zhiyuan Zhao, Qian Shi, Shaoyi Xu, Xiangyu Ye, Mengze Shen, Jia Su, Ya Wang, Tianyu Xie, Qingsong Hu, Fazhan Shi, Jiangfeng Du + Sebasti\'an Franchino-Vi\~nas, J\'er\'emie Quevillon, Diego Saviot - Revisiting Quantum Supremacy: Simulating Sycamore-Class Circuits Using Hybrid CPU/GPU HPC Workloads - https://arxiv.org/abs/2512.07311 - arXiv:2512.07311v1 Announce Type: new -Abstract: We present a framework for effectively simulating the execution of quantum circuits originally designed to demonstrate quantum supremacy using accessible high-performance computing (HPC) infrastructure. Building on prior CPU-only approaches, our pipeline combines a single NVIDIA A100 GPU for quantum state construction, followed by N parallel CPU jobs that perform distributed measurement sampling. We validate the fidelity by simulating the 53-qubit, 14-cycle Sycamore circuit and achieving a linear cross-entropy benchmarking (XEB) score of 0.549, exceeding the published XEB score of 0.002 from Google's reference data. We then evaluate execution time performance with the more complex 53-qubit, 20-cycle circuit, completing the full 2.5 million-shot workload over 100 CPU jobs in 01:15:36, representing a 6.95 x 10^7 speedup compared to Google's original classical estimate. Further, we show that if 1,000 CPU jobs were employed, the estimated duration would be approximately 00:17:35, only 12 minutes slower than the time taken by the original QPU-based experiment. These results illustrate that 'quantum supremacy' is not fixed and continues to be a moving target. In addition, hybrid classical-quantum strategies may provide broader near-term quantum utility than once thought. - oai:arXiv.org:2512.07311v1 + Entanglement Through Topological Defects: Reconciling Theory with Numerics + https://arxiv.org/abs/2512.07974 + arXiv:2512.07974v1 Announce Type: cross +Abstract: Present theoretical predictions for the entanglement entropy through topological defects are vi- olated by numerical simulations. In order to resolve this, we introduce a paradigm shift in the preparation of reduced density matrices in the presence of topological defects, and emphasize the role of defect networks with which they can be dressed. We consider the cases of grouplike and du- ality defects in detail for the Ising model, and match all numerically found entanglement entropies. Since our construction functions at the level of reduced density matrices, it accounts for topological defects beyond the entanglement entropy to other entanglement measures. + oai:arXiv.org:2512.07974v1 + hep-th + cond-mat.stat-mech + cond-mat.str-el quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Bob Wold, Venkateswaran Kasirajan + Wed, 10 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Christian Northe, Paolo Rossi - 33 Gbit/s source-device-independent quantum random number generator based on heterodyne detection with real-time FPGA-integrated extraction - https://arxiv.org/abs/2512.07319 - arXiv:2512.07319v1 Announce Type: new -Abstract: We present a high-speed continuous-variable quantum random number generator (QRNG) based on heterodyne detection of vacuum fluctuations. The scheme follows a source-device-independent (SDI) security model in which the entropy originates from quantum measurement uncertainty and no model of the source is required; security depends only on the trusted measurement device and the calibrated discretization, and thus remains valid even under adversarial state preparation. The optical field is split by a 90$^\circ$ optical hybrid and measured by two balanced photodiodes to obtain both quadratures of the vacuum state simultaneously. The analog outputs are digitized using a dual-channel 12-bit analog-to-digital converter operating at a sampling rate of 3.2 GS/s per channel, and processed in real time by an FPGA implementing Toeplitz hashing for randomness extraction. The quantum-to-classical noise ratio was verified through calibrated power spectral density measurements and cross-checked in the time domain, confirming vacuum-noise dominance within the 1.6 GHz detection bandwidth. After extraction, the system achieves a sustained generation rate of $R_{\rm net}= 33.92~\mathrm{Gbit/s}$ of uniformly distributed random bits, which pass all NIST and Dieharder statistical tests. The demonstrated platform provides a compact, FPGA-based realization of a practical heterodyne continuous-variable source-independent QRNG suitable for high-rate quantum communication and secure key distribution systems. - oai:arXiv.org:2512.07319v1 + Moire-Engineered Ferroelectric Transistors for Nearly Trap-free, Low-Power and Non-Volatile 2D Electronics + https://arxiv.org/abs/2512.08086 + arXiv:2512.08086v1 Announce Type: cross +Abstract: Long-range moire patterns in twisted WSe2 enable a built-in, moire-length-scale ferroelectric polarization that can be directly harnessed in electronic devices. Such a built-in ferroic landscape offers a compelling means to enable ultralow-voltage and non-volatile electronic functionality in two-dimensional materials; however, achieving stable polarization control without charge trapping has remained a persistent challenge. Here, we demonstrate a moire-engineered ferroelectric field-effect transistor (FeFET) utilizing twisted WSe2 bilayers that leverages atomically clean van der Waals interfaces to achieve efficient polarization-channel coupling and trap-suppressed, ultralow-voltage operation (subthreshold swing of 64 mV per decade). The device exhibits a stable non-volatile memory window of 0.10 V and high mobility, exceeding the performance of previously reported two-dimensional FeFET and matching that of advanced silicon-based devices. In addition, capacitance-voltage spectroscopy, corroborated by self-consistent Landau-Ginzburg-Devonshire modeling, indicates ultrafast ferroelectric switching (~0.5 microseconds). These results establish moire-engineered ferroelectricity as a practical and scalable route toward ultraclean, low-power, and non-volatile 2D electronics, bridging atomistic lattice engineering with functional device architectures for next-generation memory and logic technologies. + oai:arXiv.org:2512.08086v1 + cond-mat.mtrl-sci + cond-mat.mes-hall + cond-mat.str-el + physics.app-ph quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - Marius Cizauskas, Hamid Tebyanian, Mark Fox, Manfred Bayer, Marc Assmann, Alex Greilich + Arup Singha, Shaili Sett, Kenji Watanabe, Takashi Taniguchi, Arindam Ghosh, Rahul Debnath - Tunable Dynamics of a Dipolar Quantum Battery: Role of Spin-Spin Interactions and Coherence - https://arxiv.org/abs/2512.07325 - arXiv:2512.07325v1 Announce Type: new -Abstract: This study explores the energy storage dynamics of a quantum battery (QB) modeled using a dipolar spin system with Dzyaloshinskii-Moriya (DM) interaction. We examine the performance of this system in terms of ergotropy, instantaneous power, capacity, and quantum coherence using a two-qubit model. By solving the system's time evolution under cyclic unitary processes, we analyze how external parameters such as temperature, magnetic field, and DM interaction influence the charging behavior and quantum resources of the battery. The findings demonstrate that quantum coherence and DM interaction significantly enhance the energy storage efficiency and power output of the quantum battery, offering promising strategies for designing high-performance quantum energy storage devices. Furthermore, we investigate the performance of quantum battery under the influence of a common dephasing environment, which limits the long-term work-extraction capability of dipolar quantum batteries. - oai:arXiv.org:2512.07325v1 + Ab initio study of highly charged ion-induced Coulomb explosion imaging + https://arxiv.org/abs/2512.08102 + arXiv:2512.08102v1 Announce Type: cross +Abstract: We present a theoretical investigation of ion-induced Coulomb explosion imaging (CEI) of pyridazine molecules driven by energetic C$^{5+}$ projectiles, using time-dependent density-functional theory (TDDFT) with Ehrenfest nuclear dynamics. By systematically varying the projectile's impact point and orientation relative to the molecular plane, we compare orthogonal and in-plane trajectories and quantify their effects on fragment momenta, electron-density response, and atom-resolved ionization. Newton plots and time-resolved density snapshots show that trajectories avoiding direct atomic collisions yield the most faithful structural reconstructions, whereas direct impacts impart large, highly localized momenta that distort the recovered geometry. Planar trajectories generate substantially greater ionization and broader momentum distributions than orthogonal ones due to deeper traversal through the molecular electron cloud. Quantitative analysis of electron removal at 10~fs confirms that projectile proximity and orientation strongly modulate both local and global ionization. These findings clarify how impact geometry governs the fidelity of ion-induced CEI structural recovery and help explain the variability and noise observed in experimental CEI measurements. More broadly, the results highlight both the strengths and the intrinsic limitations of ion-induced CEI and identify key considerations for interpreting experiments. + oai:arXiv.org:2512.08102v1 + physics.chem-ph quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - J. Ramya Parkavi, R. Muthuganesan, V. K. Chandrasekar + Misa Viveiros, Samuel S. Taylor, Cody Covington, K\'alm\'an Varga - Dispersive readout with two orthogonal modes of a dielectric cavity - https://arxiv.org/abs/2512.07356 - arXiv:2512.07356v1 Announce Type: new -Abstract: Nitrogen-vacancy color centers in diamond have proven themselves as a good, sensitive element for the measurement of magnetic fields. While the mainstream of magnetometers based on NV centers uses so-called optically detected magnetic resonance, there has recently been a suggestion to use dispersive readout of a dielectric cavity to enhance the sensitivity of magnetometers. Here, we demonstrate that the dispersive readout approach can be significantly improved if a two-channel scheme is considered. - oai:arXiv.org:2512.07356v1 + Device/circuit simulations of silicon spin qubits based on a gate-all-around transistor + https://arxiv.org/abs/2512.08152 + arXiv:2512.08152v1 Announce Type: cross +Abstract: We theoretically investigated the readout process of a spin--qubit structure based on a gate-all-around (GAA) transistor. Our study focuses on a logical qubit composed of two physical qubits. Different spin configurations result in different charge distributions, which subsequently influence the electrostatic effects on the GAA transistor. Consequently, the current flowing through the GAA transistor depends on the qubit's state. We calculated the current-voltage characteristics of the three-dimensional configurations of the qubit and GAA structures, using technology computer-aided design (TCAD) simulations. Moreover, we performed circuit simulations using the Simulation Program with Integrated Circuit Emphasis (SPICE) to investigate whether a readout circuit made from complementary metal--oxide semiconductor (CMOS) transistors can amplify the weak signals generated by the qubits. Our findings indicate that, by dynamically controlling the applied voltage within a properly designed circuit, the readout can be detected effectively based on a conventional sense amplifier. + oai:arXiv.org:2512.08152v1 + cond-mat.mes-hall quant-ph - physics.ins-det - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - A. M. Kozodaev, I. S. Cojocaru, S. M. Drofa, P. G. Vilyuzhanina, A. Chernyavskiy, V. G. Vins, A. N. Smolyaninov, S. Ya. Kilin, S. V. Bolshedvorskii, V. V. Soshenko, A. V. Akimov + Wed, 10 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Tetsufumi Tanamoto, Keiji Ono - Intrinsic non-Markovian magnetisation dynamics - https://arxiv.org/abs/2512.07378 - arXiv:2512.07378v1 Announce Type: new -Abstract: Memory effects arise in many complex systems, from protein folding, to the spreading of epidemics and financial decisions. While so-called non-Markovian dynamics is common in larger systems with interacting components, observations in fundamental physical systems have been confined to specifically engineered cases. Here, we report the experimental observation of non-Markovian dynamics in an elemental material, crystalline cobalt. By driving this material with an intense terahertz electromagnetic field, we bring its magnetisation into a non-equilibrium state and follow its evolution. We measure the sample's low temperature magnetic response in the time domain which leads to an unexpectedly rich multi-peaked spectrum in the Fourier domain, that cannot be explained by established models. We use open quantum system theory, which predicts a non-Markovian memory kernel in the dynamical equations to capture the fundamental interaction between the spin system and the phonon bath. Simulations based on this theory produce a multi-peaked spectrum, which matches the measured one. Our non-Markovian approach is also able to reproduce the modification of the spectrum at higher temperatures. Our findings demonstrate that non-Markovian effects are observable at a much more fundamental level than previously thought, opening the door to their exploration and control in a broad range of condensed matter systems. - oai:arXiv.org:2512.07378v1 + Direct Generation of an Array with 78400 Optical Tweezers Using a Single Metasurface + https://arxiv.org/abs/2512.08222 + arXiv:2512.08222v1 Announce Type: cross +Abstract: Scalability remains a major challenge in building practical fault-tolerant quantum computers. Currently, the largest number of qubits achieved across leading quantum platforms ranges from hundreds to thousands. In atom arrays, scalability is primarily constrained by the capacity to generate large numbers of optical tweezers, and conventional techniques using acousto-optic deflectors or spatial light modulators struggle to produce arrays much beyond $\sim 10,000$ tweezers. Moreover, these methods require additional microscope objectives to focus the light into micrometer-sized spots, which further complicates system integration and scalability. Here, we demonstrate the experimental generation of an optical tweezer array containing $280\times 280$ spots using a metasurface, nearly an order of magnitude more than most existing systems. The metasurface leverages a large number of subwavelength phase-control pixels to engineer the wavefront of the incident light, enabling both large-scale tweezer generation and direct focusing into micron-scale spots without the need for a microscope. This result shifts the scalability bottleneck for atom arrays from the tweezer generation hardware to the available laser power. Furthermore, the array shows excellent intensity uniformity exceeding $90\%$, making it suitable for homogeneous single-atom loading and paving the way for trapping arrays of more than $10,000$ atoms in the near future. + oai:arXiv.org:2512.08222v1 + cond-mat.quant-gas quant-ph - cond-mat.mes-hall - cond-mat.mtrl-sci - cond-mat.stat-mech - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Felix Hartmann, Vivek Unikandanunni, Matias Bargheer, Eric E. Fullerton, Stefano Bonetti, Janet Anders + Wed, 10 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by-nc-sa/4.0/ + 10.1088/0256-307X/43/1/010606 + Yuqing Wang, Yuxuan Liao, Tao Zhang, Ye Tian, Yujia Wu, Wenjun Zhang, Wei Zhang, Yidong Huang, Hui Zhai, Wenlan Chen, Xue Feng, Zhongchi Zhang - Resonator-assisted single-photon frequency convertion in a conventional waveguide with a giant V-type atom - https://arxiv.org/abs/2512.07455 - arXiv:2512.07455v1 Announce Type: new -Abstract: We propose a scheme to achieve efficient frequency conversion for a single photon propagating in a 1D conventional waveguide by exploiting the quantum interference induced by the scale of a V-type giant atom (GA) characterized by the distance between the two coupling points as well as single-photon transition pathways originated from the coupling between the GA and the resonator. The presence of photons in the resonator triggers the frequency conversion of photons. The scattering spectra and the conversion contrast are studied in both the Markovian and the non-Markovian regimes. The disappearance of frequency conversion is rooted in the complete suppression of the emission from the excited state to either of lower states in the $n+1$ subspace where $n$ is the photon number of the resonator, and the non-Markovicity-induced nonreciprocity is found under specific conditions. Altering the photon number $n$ induces the non-reciprocal transmission of single photons in the waveguide, hence, enhance the conversion probability. - oai:arXiv.org:2512.07455v1 + Decay of spin helices in XXZ quantum spin chains with single-ion anisotropy + https://arxiv.org/abs/2512.08421 + arXiv:2512.08421v1 Announce Type: cross +Abstract: Long-lived spin-helix states facilitate the study of non-equilibrium dynamics in quantum magnets. We consider the decay of transverse spin-helices in antiferromagnetic spin-$S$ XXZ chains with single-ion anisostropy. The spin-helix decay is observable in the time evolution of the local magnetization that we calculate numerically for the system in the thermodynamic limit using infinite time-evolving block decimation simulations. Although the single-ion anisotropy prevents helix states from being eigenstates of the Hamiltonian, they still can be long-lived for appropriately chosen wave numbers. In case of an easy-axis exchange anisotropy the single-ion anisotropy may even stabilize the helices. Within a spin-wave approximation, we obtain a condition giving an estimate for the most stable wave number $Q$ that agrees qualitatively with our numerical results. + oai:arXiv.org:2512.08421v1 + cond-mat.str-el quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ge Sun, Hongzheng Wu, Jing Lu, Lan Zhou + Florian Lange, Frank G\"ohmann, Gerhard Wellein, Holger Fehske - On the emergence of preferred structures in quantum theory - https://arxiv.org/abs/2512.07468 - arXiv:2512.07468v1 Announce Type: new -Abstract: We assess the possibilities offered by Hilbert space fundamentalism, an attitude towards quantum physics according to which all physical structures (e.g. subsystems, locality, spacetime, preferred observables) should emerge from minimal quantum ingredients (typically a Hilbert space, Hamiltonian, and state). As a case study, we first mainly focus on the specific question of whether the Hamiltonian can uniquely determine a tensor product structure, a crucial challenge in the growing field of quantum mereology. The present paper reviews, clarifies, and critically examines two apparently conflicting theorems by Cotler et al. and Stoica. We resolve the tension, show how the former has been widely misinterpreted and why the latter is correct only in some weaker version. We then propose a correct mathematical way to address the general problem of preferred structures in quantum theory, relative to the characterization of emergent objects by unitary-invariant properties. Finally, we apply this formalism in the particular case we started with, and show that a Hamiltonian and a state are enough structure to uniquely select a preferred tensor product structure. - oai:arXiv.org:2512.07468v1 - quant-ph + Radiative process of tripartite entangled probes in inertial motion + https://arxiv.org/abs/2512.08578 + arXiv:2512.08578v1 Announce Type: cross +Abstract: We study the radiative process of three entangled quantum probes initially prepared in a tripartite W state. As a basic set-up, we consider the probes to be inertial in flat spacetime and investigate how the radiative process is affected by different probe configurations. We take the quantum probes as either static or moving with uniform velocities and consider different switching scenarios. Our main observation confirms that the radiative process depends distinctively on the initial configuration in which the probes are arranged, as well as on the direction of the probe velocity. We also extend our analysis to a thermal environment, thereby simulating a more realistic background. We thoroughly discuss the effects due to different switchings, the thermal background, and probe motion on the radiative process of these tripartite entangled probes. We also comment on how the observations from this work can help prepare a set-up least affected by quantum decoherence. + oai:arXiv.org:2512.08578v1 + gr-qc hep-th - math-ph - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Antoine Soulas, Guilherme Franzmann, Andrea Di Biagio - - - RuleSet Generation Framework for Application Layer Integration in Quantum Internet - https://arxiv.org/abs/2512.07475 - arXiv:2512.07475v1 Announce Type: new -Abstract: Layered architectures for the Quantum Internet have been proposed, inspired by that of the classical Internet, which has demonstrated high maintainability even in large-scale systems. While lower layers in the Quantum Internet, such as entanglement generation and distribution, have been extensively studied, the application layer - responsible for translating user requests into executable quantum-network operations - remains largely unexplored. A significant challenge is translating application-level requests into the concrete instructions executable at lower layers. In this work, we introduce a RuleSet-based framework that explicitly incorporates the application layer into the layered architecture of the Quantum Internet. Our framework builds on a RuleSet-based protocol, clarifying communication procedures, organizing application request information, and introducing new Rules for application execution by embedding application specifications into RuleSets. To evaluate feasibility, we constructed state machines from the generated RuleSets. This approach enables a transparent integration from the application layer down to the physical layer, thereby lowering barriers to deploying new applications on the Quantum Internet. - oai:arXiv.org:2512.07475v1 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Rei Kawano, Shin Nishio, Hideaki Kawaguchi, Shota Nagayama, Takahiko Satoh + Wed, 10 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Subhajit Barman, K. Hari - Mediated Transmission of Quantum Synchronization in Star Networks - https://arxiv.org/abs/2512.07496 - arXiv:2512.07496v1 Announce Type: new -Abstract: Synchronization transmission describes the emergence of coherence between two uncoupled oscillators mediated by their mutual coupling to an intermediate one. In classical star networks, such mediated coupling gives rise to remote synchronization--where nonadjacent leaf nodes synchronize through a nonsynchronous hub--and to explosive synchronization, characterized by an abrupt collective transition to coherence. In the quantum regime, analogous effects can arise from the interplay between 1:1 phase locking and 2:1 phase-locking blockade in coupled spin-1 oscillators. In this work, we investigate a star network composed of spin-1 oscillators. For identical oscillators, symmetric and asymmetric dissipation lead to distinct transmission behaviors: remote synchronization and quasi-explosive synchronization appear in different coupling regimes, a phenomenon absent in classical counterparts. For nonidentical networks, we find that at large detuning remote synchronization emerges in the weak-coupling regime and evolves into quasi-explosive synchronization as the coupling increases, consistent with classical star-network dynamics. These findings reveal the rich dynamical characteristics of mediated quantum synchronization and point toward new possibilities for exploring synchronization transmission in larger and more complex quantum systems. - oai:arXiv.org:2512.07496v1 + Anisotropic transport in ballistic bilayer graphene cavities + https://arxiv.org/abs/2512.08588 + arXiv:2512.08588v1 Announce Type: cross +Abstract: Closing the gap between ray tracing simulations and experimentally observed electron jetting in bilayer graphene (BLG), we study all-electronic, gate-defined BLG cavities using tight-binding simulations and semiclassical equations of motion. Such cavities offer a rich playground to investigate anisotropic electron transport due to the trigonally warped Fermi surfaces. In this work, we achieve two things: First, we verify the existence of triangular modes (as predicted by classical ray tracing calculations) in the quantum solutions of closed circular BLG cavities. Then, we explore signatures of said triangular modes in transport through open BLG cavities connected to leads. We show that the triangular symmetry translates into anisotropic transport and present an optimal setup for experimental detection of the triangular modes as well as for controlled modulation of transport in preferred directions. + oai:arXiv.org:2512.08588v1 + cond-mat.mes-hall quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Shuo Dai, Ran Qi + Florian Schoeppl, Alina Mrenca-Kolasinska, Ming-Hao Liu, Korbinian Schwarzmaier, Klaus Richter, Angelika Knothe - Exponentially accelerated relaxation and quantum Mpemba effect in open quantum systems - https://arxiv.org/abs/2512.07561 - arXiv:2512.07561v1 Announce Type: new -Abstract: We investigate the quantum Mpemba effect in the relaxation of open quantum systems whose effective dynamics is described by Davies maps. We present a class of unitary transformations based on permutation matrices that, acting on the initial state of the system, (i) suppress the contribution of slowest decaying modes of the nonunitary dynamics; (ii) ensure that it is as distinguishable as possible from the steady state. The first requirement guarantees an exponentially accelerating convergence to the steady state, while the second implies that a quantum system initially farther from equilibrium approaches it more rapidly than an initial state closer to it. This protocol provides a genuine Mpemba effect, and its numerical simulation requires low computational effort. We prove that, for any initial state, there always exists a permutation matrix that maximizes its distance from the equilibrium for a given information-theoretic distinguishability measure. We illustrate our findings for the nonunitary dynamics of the transverse field Ising chain and XXZ chain, each weakly coupled to a bosonic thermal bath, showing the quantum Mpemba effect captured by the Hilbert-Schmidt distance, quantum relative entropy, and trace distance. Our results provide a universal and versatile framework to engineer the genuine quantum Mpemba effect in open quantum systems. - oai:arXiv.org:2512.07561v1 + Operator Lanczos Approach enabling Neural Quantum States as Real-Frequency Impurity Solvers + https://arxiv.org/abs/2512.08624 + arXiv:2512.08624v1 Announce Type: cross +Abstract: To understand the intricate exchange between electrons of different bands in strongly correlated materials, it is essential to treat multi-orbital models accurately. For this purpose, dynamical mean-field theory (DMFT) provides an established framework, whose scope crucially hinges on the availability of efficient quantum impurity solvers. Here we present a real-frequency impurity solver based on neural quantum states (NQS) combined with an operator-Lanczos construction. NQS are an asymptotically unbiased variational ground-state ansatz that employs neural networks to capture long-range correlations on complicated graph structures. We leverage this ability to solve multi-orbital impurity problems using a systematically improvable Segmented Commutator Operator-Lanczos (SCOL) construction. Our benchmarks on both the single-orbital Anderson model and the multi-orbital Hubbard-Kanamori impurity Hamiltonian reveal excellent ground-state precision and the capacity to accurately resolve zero temperature spectral functions and self-energies. These results open avenues for extending DMFT to more challenging problems. + oai:arXiv.org:2512.08624v1 + cond-mat.str-el quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Emerson Lima Caldas, Diego Paiva Pires + Jonas B. Rigo, Markus Schmitt - Uniform relativistic motion through a thermal bath as a thermodynamic resource - https://arxiv.org/abs/2512.07567 - arXiv:2512.07567v1 Announce Type: new -Abstract: We show that a quantum system undergoing motion with uniform relativistic velocity through a thermal bath consisting of a massless scalar field is generically driven into a non-equilibrium steady-state (NESS) solely due to its motion, even in the absence of external driving or multiple baths. The relative motion between the system and the bath breaks detailed balance, preventing thermalization to a Gibbs state. We find that the resulting steady-states fall into two distinct classes: (i) NESSs with persistent probability currents, and (ii) current-free non-Gibbs steady states characterized by a frequency-dependent effective inverse temperature. We demonstrate, using a three-level system, that NESSs with probability current can function as noisy stochastic clock, while current-free non-Gibbs steady states possess non-zero non-equilibrium free energy, indicating their potential as a quantum battery for work extraction or storage. - oai:arXiv.org:2512.07567v1 + The bound state of dark atom with the nucleus of substance + https://arxiv.org/abs/2512.08718 + arXiv:2512.08718v1 Announce Type: cross +Abstract: The hypothesis of composite $XHe$ dark atoms offers a compelling framework to address the challenges in direct dark matter particles detection, as their neutral, atom-like configuration evades conventional experimental signatures. A critical issue may arise in interaction between $XHe$ and atomic nuclei due to the unshielded nuclear attraction, which could destabilize the dark atom's bound state. To resolve this, we propose a novel numerical quantum mechanical approach that accounts for self-consistent electromagnetic-nuclear couplings. This method addresses to eliminate the inherent complexity of the $XHe$-nucleus three-body system, where analytical solutions are intractable. By reconstructing the effective interaction potential - including dipole Coulomb barrier and shallow potential well - we demonstrate how these features lead to the formation of $XHe$-nucleus bound states and modulate low-energy capture processes. Our model enables validation of the dark atom hypothesis, particularly in interpreting experimental anomalies like annual modulation signals observed in DAMA/LIBRA. These findings advance the theoretical foundation for dark matter interactions and provide a robust framework for future experimental design. + oai:arXiv.org:2512.08718v1 + hep-ph quant-ph - hep-th - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Rahul Shastri + T. E. Bikbaev, M. Yu. Khlopov, A. G. Mayorov - On-Demand Microwave Single-Photon Source Based on Tantalum Thin Film - https://arxiv.org/abs/2512.07589 - arXiv:2512.07589v1 Announce Type: new -Abstract: Single-photon sources are crucial for quantum information technologies. Here, we demonstrate a microwave single-photon source fabricated using a tantalum-based thin film, whose favorable material properties enable high-quality and stable photon emission. The antibunching behavior of the emitted radiation is revealed by second-order correlation measurements. Furthermore, traveling-wave parametric amplifiers are used as the pre-amplifier in the detection chains, we substantially improve the signal-to-noise ratio and thereby greatly reduce the acquisition time required for second-order correlation measurements. These results demonstrate the viability of tantalum-based superconducting devices as reliable platforms for microwave quantum photonics. - oai:arXiv.org:2512.07589v1 + Fluctuation-Induced Supersolidity at the Superfluid-Solid Interface + https://arxiv.org/abs/2512.08739 + arXiv:2512.08739v1 Announce Type: cross +Abstract: Supersolidity, combining superfluid and crystalline orders, has been realized in dipolar Bose-Einstein condensates by tuning interatomic interactions. Here we show that supersolidity can also emerge from mode coupling at a superfluid-solid interface, without modifying bulk interactions and for a broad class of superfluids. Using an analytical and numerical treatment of the coupled superfluid and phonon fields, we derive the criterion for a density-modulation instability driven by interfacial coupling and dependent on dimensionality. In superfluid helium, the instability first appears at the roton mode, while in a Bose-Einstein condensate with contact interactions it occurs at the lowest accessible wave vector set by the system size. Beyond the threshold, the ground state acquires an interfacial density modulation while the bulk remains superfluid, forming a hybrid superfluid-supersolid phase. Our results identify interfacial mode coupling as a promising route to supersolidity, enabling the simultaneous exploitation of interfacial supersolid and bulk superfluid quantum properties. + oai:arXiv.org:2512.08739v1 + cond-mat.quant-gas + cond-mat.mes-hall quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ying Hu, Sheng-Yong Li, En-Qi Chen, Jing Zhang, Yu-xi Liu, Jia-Gui Feng, Zhihui Peng + Wed, 10 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Baptiste Coquinot, Ragheed Alhyder, Alberto Cappellaro, Mikhail Lemeshko - Sharp values for all dynamical variables via Anti-Wick quantization - https://arxiv.org/abs/2512.07616 - arXiv:2512.07616v1 Announce Type: new -Abstract: This paper proposes an approach to interpreting quantum expectation values that may help address the quantum measurement problem. Quantum expectation values are usually calculated via Hilbert space inner products and, thereby, differently from expectation values in classical mechanics, which are weighted phase-space integrals. It is shown that, by using Anti-Wick quantization to associate dynamical variables with self-adjoint linear operators, quantum expectation values can be interpreted as genuine weighted averages over phase space, paralleling their classical counterparts. This interpretation arises naturally in the Segal-Bargmann space, where creation and annihilation operators act as simple multiplication and differentiation operators. In this setting, the Husimi Q-function - the coherent-state representation of the quantum state - can be seen as a true probability density in phase space. Unlike Bohmian mechanics, the present approach retains the standard correspondence between dynamical variables and self-adjoint operators while paving the way for a classical-like probabilistic interpretation of quantum statistics. - oai:arXiv.org:2512.07616v1 + Vacuum Energy and Topological Mass in Interacting Elko and Scalar Field Theories + https://arxiv.org/abs/2512.08750 + arXiv:2512.08750v1 Announce Type: cross +Abstract: In this paper, we consider a four-dimensional system composed of a mass-dimension-one fermionic field, also known as Elko, interacting with a real scalar field. Our main objective is to analyze the Casimir effects associated with this system, assuming that both the Elko and scalar fields satisfy Dirichlet boundary conditions on two large parallel plates separated by a distance $L$. In this scenario, we calculate the vacuum energy density and its first-order correction in the coupling constants of the theory. Additionally, we consider the mass correction for each field separately, namely the topological mass that arises from the boundary conditions imposed on the fields and which also depends on the coupling constants. To develop this analysis, we use the mathematical formalism known as the effective potential, expressed as a path integral in quantum field theory. + oai:arXiv.org:2512.08750v1 + hep-th + math-ph + math.MP quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - 10.1016/j.physleta.2025.131226. - Physics Letters A, Volume 567, 2026, 131226, ISSN 0375-9601, Physics Letters A, 567: 131226 (2026) - Simon Friederich + A. J. D. Farias Junior, A. Smirnov, Herondy F. Santana Mota, E. R. Bezerra de Mello - Quantum Diamond Microscopy for Non-Destructive Failure Analysis of an Integrated Fan-Out Package-on-Package iPhone Chip - https://arxiv.org/abs/2512.07619 - arXiv:2512.07619v1 Announce Type: new -Abstract: The increasing complexity of advanced semiconductor packages, driven by chiplet architectures and 2.5D/3D integration, challenges conventional failure localization methods such as lock-in thermography (LIT) and complicates current Failure Analysis (FA) workflows. Dense redistribution layers and buried interconnects limit the ability of established techniques to understand failure mechanisms non-destructively. In this work, we validate quantum diamond microscopy (QDM) based on nitrogen-vacancy (NV) centers in diamond as a non-destructive localization method through magnetic current path imaging at the package level. Using commercial Integrated Fan-Out Package-on- Package (InFO-PoP) devices from iPhones, we showcase a complete FA workflow that includes QDM to localize a short-type failure at an Integrated Passive Device (IPD) at the package backside. We showcase that the QDM results provide invaluable information on top of conventional techniques and can significantly enhance root-cause identification in package-level FA workflows. This work demonstrates the potential of QDM for broader integration into semiconductor chip and package analysis workflows. - oai:arXiv.org:2512.07619v1 + Correlation length in random MPS and PEPS + https://arxiv.org/abs/1906.11682 + arXiv:1906.11682v4 Announce Type: replace +Abstract: Tensor network states are used extensively as a mathematically convenient description of physically relevant states of many-body quantum systems. Those built on regular lattices, i.e. matrix product states (MPS) in dimension 1 and projected entangled pair states (PEPS) in dimension 2 or higher, are of particular interest in condensed matter physics. The general goal of this work is to characterize which features of MPS and PEPS are generic and which are, on the contrary, exceptional. This problem can be rephrased as follows: given an MPS or PEPS sampled at random, what are the features that it displays with either high or low probability? One property which we are particularly interested in is that of having either rapidly decaying or long-range correlations. In a nutshell, our main result is that translation-invariant MPS and PEPS typically exhibit exponential decay of correlations at a high rate. We have two distinct ways of getting to this conclusion, depending on the dimensional regime under consideration. Both yield intermediate results which are of independent interest, namely: the parent Hamiltonian and the transfer operator of such MPS and PEPS typically have a large spectral gap. In all these statements, our aim is to get a quantitative estimate of the considered quantity (generic correlation length or spectral gap), which has the best possible dependency on the physical and bond dimensions of the random MPS or PEPS. + oai:arXiv.org:1906.11682v4 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + cond-mat.str-el + hep-th + math-ph + math.MP + math.PR + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - Bartu Bisgin, Marwa Garsi, Andreas Welscher, Michael Hanke, Fleming Bruckmaier + 10.1007/s00023-021-01087-4 + Annales Henri Poincare, Vol. 23, pp. 141-222 (2022) + C\'ecilia Lancien, David P\'erez-Garc\'ia - Enhanced charging power in nonreciprocal quantum battery by reservoir engineering - https://arxiv.org/abs/2512.07626 - arXiv:2512.07626v1 Announce Type: new -Abstract: We propose a scheme to achieve a nonreciprocal quantum battery (QB) in the non-Hermitian (NH) system, which can overcome the intrinsic dissipation and reverse flow constraints. The design is based on a charger and a battery, which are coherently coupled and jointly interact with a bad cavity. By introducing the auxiliary bad cavity and exploiting the nonreciprocal condition, this model can harness the environmental dissipation to suppress the reverse energy transfer. Under resonant conditions, we have achieved a four ratio of the battery energy to the charger energy; in contrast, this ratio is significantly reduced under large detuning. Through damping optimization, high efficiency of the short-time charging power is attained. In comparison to the fully nonreciprocal scheme, the QB operating at the exceptional point (EP) exhibits greater resilience to parameter fluctuations. These findings highlight the potential of NH quantum engineering for advancing QB technology, particularly in regimes involving directional energy transfer, controlled dissipation, and entropy management in open quantum systems. - oai:arXiv.org:2512.07626v1 + Anti-Hong-Ou-Mandel interference by coherent perfect absorption of entangled photons + https://arxiv.org/abs/2105.05444 + arXiv:2105.05444v2 Announce Type: replace +Abstract: Two-photon interference, known as the Hong-Ou-Mandel effect, has colossal implications for quantum technology. It was observed in 1987 with two photodetectors monitoring outputs of the beamsplitter illuminated by photon pairs: the coincidence rate of the detectors drops to zero when detected photons overlap in time. More broadly, bosons (e.g., photons) coalesce while fermions (e.g., electrons) anti-coalesce when interfering on a lossless beamsplitter. Quantum interference of bosons and fermions can be tested in a single - photonics platform, where bosonic and fermionic states are artificially created as pairs of entangled photons with symmetric and anti-symmetric spatial wavefunctions. We observed that interference on a lossy beamsplitter, or a subwavelength coherent absorber reverses quantum interference in such a way that bosonic states anti-coalesce while fermionic states exhibit coalescent-like behavior. The ability to generate states of light with different statistics and manipulate their interference offers important opportunities for quantum information and metrology. + oai:arXiv.org:2105.05444v2 quant-ph - physics.app-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Qi-Yin Lin, Guang-Zheng Ye, Can Li, Wan-Jun Su, Huai-Zhi Wu + 10.1088/1367-2630/ac9fe9 + New J. Phys. 24 122001 (2022) + Anton N. Vetlugin, Ruixiang Guo, Cesare Soci, Nikolay I. Zheludev - Single-Operation Rydberg Phase Gates via Dynamic Population Suppression - https://arxiv.org/abs/2512.07656 - arXiv:2512.07656v1 Announce Type: new -Abstract: We propose a versatile control protocol based on modulated zero-pulse-area fields that dynamically suppresses Rydberg excitation while retaining Rydberg-Rydberg interactions as an entangling phase resource. This mechanism enables single-step, perfectly entangling phase gates for arbitrary blockade strengths, eliminating finite-blockade errors even when the Rabi frequency approaches or exceeds the interaction energy. The approach defines a new operational regime for Rydberg-blockade quantum logic in which speed, fidelity, and robustness are achieved simultaneously within a simple dynamical framework. Owing to its simplicity and generality, the technique is compatible with a wide range of neutral-atom architectures and offers a promising route toward scalable, high-fidelity quantum computation and simulation. - oai:arXiv.org:2512.07656v1 + An Appropriate Probability Model for the Bell Experiment + https://arxiv.org/abs/2302.05174 + arXiv:2302.05174v2 Announce Type: replace +Abstract: The Bell inequality constrains the outcomes of measurements on pairs of distant entangled particles. The Bell contradiction states that the Bell inequality is inconsistent with the calculated outcomes of these quantum experiments. This contradiction led many to question the underlying assumptions, viz. so-called realism and locality. The probability model underlying the Bell inequality is generally left implicit. This implicit consensus model assumes four simultaneously observable detector settings. The Bell contradiction follows from this assumption. + We propose an explicit probability model for the CHSH version of the Bell experiment. This model has only two simultaneously observable detector settings per measurement, and therefore does not assume realism. The quantum expectation now becomes a conditional expectation, given the two detector settings. This probability model is in full agreement with both quantum mechanics and experiments. In this model the notion of Bell contradiction has no meaning. Furthermore, the proposed probability model is statistically local, and is not Bell-separable. The latter implies that either hidden variables must be ruled out, or that locality must be violated, in agreement with Bell's conclusion. + oai:arXiv.org:2302.05174v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sebastian C. Carrasco, Jabir Chathanathil, Svetlana A. Malinovskaya, Ignacio Sola, Vladimir S. Malinovsky + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Kees van Hee, Kees van Berkel, Jan de Graaf - Brazilian Twin Photons 32nd anniversary - https://arxiv.org/abs/2512.07670 - arXiv:2512.07670v1 Announce Type: new -Abstract: We present a historical review of the development and impact of spontaneous parametric down-conversion (SPDC) in Brazil, marking over three decades since the first twin-photon experiments were performed in the country. This article traces the pioneering efforts that initiated the field, highlighting key experiments, institutions, and researchers who contributed to its growth. We discuss seminal works that established SPDC as a fundamental tool in the Brazilian Quantum Optics community, including studies on spatial correlations, entanglement, and decoherence. By presenting a curated sequence of experiments, we offer an overview of how Brazilian research in twin-photon systems has explored profound concepts through fundamental demonstrations, leading to significant international impact. This review also highlights the formation of a strong scientific community and its ongoing efforts to turn fundamental knowledge into quantum applications. - oai:arXiv.org:2512.07670v1 + Self-Testing Graph States Permitting Bounded Classical Communication + https://arxiv.org/abs/2404.03496 + arXiv:2404.03496v4 Announce Type: replace +Abstract: Self-testing identifies quantum states and correlations that exhibit nonlocality, distinguishing them, up to local transformations, from other quantum states. Due to their strong nonlocality, it is known that all graph states can be self-tested in the standard setting - where parties are not allowed to communicate. Recently it has been shown that graph states display nonlocal correlations even when bounded classical communication on the underlying graph is permitted, a feature that has found applications in proving a circuit-depth separation between classical and quantum computing. In this work, we develop self testing in the framework of bounded classical communication, and we show that certain graph states can be robustly self-tested even allowing for communication. In particular, we provide an explicit self-test for the circular graph state and the honeycomb cluster state - the latter known to be a universal resource for measurement based quantum computation. Since communication generally obstructs self-testing of graph states, we further provide a procedure to robustly self-test any graph state from larger ones that exhibit nonlocal correlations in the communication scenario. + oai:arXiv.org:2404.03496v4 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Renn\'e Medeiros de Ara\'ujo (Departamento de F\'isica, Universidade Federal de Santa Catarina, Brazil), Raphael C\'esar Souza Pimenta (Departamento de F\'isica, Universidade Federal de Santa Catarina, Brazil), Lucas Marques Fagundes (Departamento de F\'isica, Universidade Federal de Santa Catarina, Brazil), Gustavo Henrique dos Santos (Departamento de F\'isica, Universidad de Concepci\'on, Chile, Millennium Institute for Research in Optics, Universidad de Concepci\'on, Chile), Nara Rubiano da Silva (Departamento de F\'isica, Universidade Federal de Santa Catarina, Brazil), Stephen Patrick Walborn (Departamento de F\'isica, Universidad de Concepci\'on, Chile, Millennium Institute for Research in Optics, Universidad de Concepci\'on, Chile), Paulo Henrique Souto Ribeiro (Departamento de F\'isica, Universidade Federal de Santa Catarina, Brazil) + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Uta Isabella Meyer, Ivan \v{S}upi\'c, Fr\'ed\'eric Grosshans, Damian Markham - A scalable and real-time neural decoder for topological quantum codes - https://arxiv.org/abs/2512.07737 - arXiv:2512.07737v1 Announce Type: new -Abstract: Fault-tolerant quantum computing will require error rates far below those achievable with physical qubits. Quantum error correction (QEC) bridges this gap, but depends on decoders being simultaneously fast, accurate, and scalable. This combination of requirements has not yet been met by a machine-learning decoder, nor by any decoder for promising resource-efficient codes such as the colour code. Here we introduce AlphaQubit 2, a neural-network decoder that achieves near-optimal logical error rates for both surface and colour codes at large scales under realistic noise. For the colour code, it is orders of magnitude faster than other high-accuracy decoders. For the surface code, we demonstrate real-time decoding faster than 1 microsecond per cycle up to distance 11 on current commercial accelerators with better accuracy than leading real-time decoders. These results support the practical application of a wider class of promising QEC codes, and establish a credible path towards high-accuracy, real-time neural decoding at the scales required for fault-tolerant quantum computation. - oai:arXiv.org:2512.07737v1 + Chasing shadows with Gottesman-Kitaev-Preskill codes + https://arxiv.org/abs/2411.00235 + arXiv:2411.00235v4 Announce Type: replace +Abstract: We consider the task of performing shadow tomography of a logical subsystem defined via the Gottesman-Kitaev-Preskill (GKP) error correcting code. Our protocol does not require the input state to be a code state but is implemented by appropriate twirling of the measurement channel, such that the encoded logical tomographic information becomes encoded in the classical shadow. We showcase this protocol for measurements natural in continuous variable (CV) quantum computing. For heterodyne measurement, the protocol yields a probabilistic decomposition of any input state into Gaussian states that simulate the encoded logical information of the input relative to a fixed GKP code where we prove bounds on the Gaussian compressibility of states in this setting. For photon parity measurements, our protocol is equivalent to a Wigner sampling protocol for which we develop the appropriate sampling strategies. Finally, by randomizing over the reference GKP code, we show how Wigner samples of any input state relative to a random GKP codes can be used to estimate any sufficiently bounded observable. + oai:arXiv.org:2411.00235v4 quant-ph - cs.LG - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - Andrew W. Senior, Thomas Edlich, Francisco J. H. Heras, Lei M. Zhang, Oscar Higgott, James S. Spencer, Taylor Applebaum, Sam Blackwell, Justin Ledford, Akvil\.e \v{Z}emgulyt\.e, Augustin \v{Z}\'idek, Noah Shutty, Andrew Cowie, Yin Li, George Holland, Peter Brooks, Charlie Beattie, Michael Newman, Alex Davies, Cody Jones, Sergio Boixo, Hartmut Neven, Pushmeet Kohli, Johannes Bausch + Jonathan Conrad, Jens Eisert, Steven T. Flammia - Real-time collisions of fractional charges in a trapped-ion Jackiw-Rebbi field theory - https://arxiv.org/abs/2512.07748 - arXiv:2512.07748v1 Announce Type: new -Abstract: We propose and analyze a trapped-ion quantum simulator of the Jackiw-Rebbi model, a paradigmatic quantum field theory in (1+1) dimensions where solitonic excitations of a scalar field can bind fermionic zero modes leading to fractionally charged excitations. In our approach, the scalar field is a coarse-grained description of the planar zigzag ion displacements in the vicinity of a structural phase transition. The internal electronic states of the ions encode spins with interactions mediated by the transverse phonons and in-plane spin-phonon couplings with a zigzag pattern, which together correspond to a Yukawa-coupled Dirac field. Instead of assuming a fixed soliton background, we study the effect of back-reaction and quantum fluctuations on the coupled dynamics of the full fermion-boson system. We start by applying a Born-Oppenheimer approximation to obtain an effective Peierls-Nabarro potential for the topological kink, unveiling how the fermionic back-reaction can lead to localization of the kink. Beyond this limit, a truncated Wigner approximation combined with fermionic Gaussian states captures the quantum spreading and localization of a kink and kink-antikink scattering. Our results reveal how back-reaction and quantum fluctuations modify the stability and real-time evolution of fractionalized fermions, predicting experimentally accessible signatures in current trapped-ion architectures. - oai:arXiv.org:2512.07748v1 + Quantum-limited estimation of the frequency shift between two interfering photons by time sampling of their quantum beats + https://arxiv.org/abs/2412.16304 + arXiv:2412.16304v2 Announce Type: replace +Abstract: We present a sensing scheme for estimating the frequency difference of two non-entangled photons. The technique consists of time-resolving sampling measurements at the output of a beam splitter. With this protocol, the frequency shift between two photons can be estimated with the ultimate precision achievable in nature, overcoming the limits in precision and the range of detection of frequency-resolving detectors employed in standard direct measurements of the frequencies. The sensitivity can be increased by increasing the coherence time of the photons. We show that, already with $\sim 1000$ sampling measurements, the Cram\'{e}r-Rao bound is saturated independently of the value of the difference in frequency. + oai:arXiv.org:2412.16304v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - Alan Kahan, Pablo Vi\~nas, Torsten V. Zache, Alejandro Bermudez + 10.1140/epjp/s13360-025-06903-y + The European Physical Journal Plus 140, 954 (2025) + Luca Maggio, Danilo Triggiani, Paolo Facchi, Vincenzo Tamma - Statistical properties of quantum jumps between macroscopic states of light: reading an operational coherence record - https://arxiv.org/abs/2512.07754 - arXiv:2512.07754v1 Announce Type: new -Abstract: We propose an experimental apparatus to reveal the quantum coherence manifested in downward quantum jumps of amplitude bistability. The underlying coherent superposition of macroscopic quantum states is translated into the statistical properties of the integrated charge deposited in the detector circuit of a mode-matched heterodyne/homodyne detection scheme. At first, the dynamical evolution of a signal transmitted from an auxiliary cavity is employed to pinpoint a macroscopic switching event in a bistable main cavity subject to direct photodetection. Once the decision is made on the occurrence of a downward switch, the main cavity mode is let to freely decay to the vacuum, monitored to the production of an integrated charge. In the long-time limit, the charge distribution over an identical collection of pure states generated during the jumps converges to the Q function (heterodyne detection) or marginals of the Wigner function (homodyne detection) dictated by the phase of the local oscillator. When fluctuations over the ensemble step in, we connect the statistical properties of several switching events and the ensuing production of current records, to the cavity field correlations associated with the breakdown of photon blockade. - oai:arXiv.org:2512.07754v1 + Benchmarking quantum devices beyond classical capabilities + https://arxiv.org/abs/2502.02575 + arXiv:2502.02575v3 Announce Type: replace +Abstract: Rapid development of quantum computing technology has led to a wide variety of sophisticated quantum devices. Benchmarking these systems becomes crucial for understanding their capabilities and paving the way for future advancements. The Quantum Volume (QV) test is one of the most widely used benchmarks for evaluating quantum computer performance due to its architecture independence. However, as the number of qubits in a quantum device grows, the test faces a significant limitation: classical simulation of the quantum circuit, which is indispensable for evaluating QV, becomes computationally impractical. In this work, we propose modifications of the QV test that allow for direct determination of the most probable outcomes of a quantum circuit, eliminating the need for expensive classical simulations. This approach resolves the scalability problem of the Quantum Volume test beyond classical computational capabilities, while still examining key features of universal quantum computing. + oai:arXiv.org:2502.02575v3 quant-ph - cond-mat.mes-hall - physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Th. K. Mavrogordatos + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-sa/4.0/ + Rafa{\l} Bistro\'n, Marcin Rudzi\'nski, Ryszard Kukulski, Karol \.Zyczkowski - Strongly driven cavity quantum electrodynamical-optomechanical hybrid system - https://arxiv.org/abs/2512.07788 - arXiv:2512.07788v1 Announce Type: new -Abstract: Hybrid quantum systems harness the distinct advantages of different physical platforms, yet their integration is not always trivial due to potential incompatibilities in operational principles. Here, we theoretically propose and demonstrate a scheme for generating non-Gaussian mechanical states using a strongly driven hybrid system that combines cavity quantum electrodynamics (QED) and cavity optomechanics. Our protocol prepares a non-Gaussian cavity state in the dispersive regime of cavity QED and subsequently transfers it to a mechanical oscillator using the optomechanical interaction enhanced by a coherent cavity drive. While non-Gaussian cavity state control in cavity QED is well established in the dispersive regime, its behavior under strong cavity drive, essential for cavity optomechanics, remains largely unexplored. To bridge this gap, we develop an efficient simulation framework to model cavity QED dynamics in the high-photon-number regime. We show that a strong cavity drive can coherently displace the cavity state with minimal perturbations, effectively decoupling it from the qubit. The resulting large coherent cavity field enhances the optomechanical coupling strength, enabling high-fidelity transfer of non-Gaussian cavity states to the mechanical mode. These results reveal new dynamical features of driven cavity QED and open a pathway toward realizing non-Gaussian mechanical quantum memories and sensors. - oai:arXiv.org:2512.07788v1 + Formal Integration of Electron Scattering Processes via Separation of Dynamical and Geometric Contributions + https://arxiv.org/abs/2502.09360 + arXiv:2502.09360v4 Announce Type: replace +Abstract: By decoupling the geometric from the dynamical contributions in the scattering processes, we develop a method to compute the scattering matrix of electrons in a one-dimensional coherent conductor connected to two electrodes. In particular, we demonstrate that, in the high-energy regime, the transmission matrix converges to the Berry operator of the system. We showcase the method through several examples featuring different in-plane magnetic field profiles. Notably, our results reveal the possibility of achieving near-perfect spin-flip transmission, highlighting potential applications in spintronics. + oai:arXiv.org:2502.09360v4 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xuxin Wang, Jiahe Pan, Tobias J. Kippenberg, Shingo Kono + cond-mat.mes-hall + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.1088/1751-8121/ae2995 + Bagnasacco et al 2025 J. Phys. A: Math. Theor + Lorenzo Bagnasacco, Fabio Taddei, Vittorio Giovannetti - LUNA: LUT-Based Neural Architecture for Fast and Low-Cost Qubit Readout - https://arxiv.org/abs/2512.07808 - arXiv:2512.07808v1 Announce Type: new -Abstract: Qubit readout is a critical operation in quantum computing systems, which maps the analog response of qubits into discrete classical states. Deep neural networks (DNNs) have recently emerged as a promising solution to improve readout accuracy . Prior hardware implementations of DNN-based readout are resource-intensive and suffer from high inference latency, limiting their practical use in low-latency decoding and quantum error correction (QEC) loops. This paper proposes LUNA, a fast and efficient superconducting qubit readout accelerator that combines low-cost integrator-based preprocessing with Look-Up Table (LUT) based neural networks for classification. The architecture uses simple integrators for dimensionality reduction with minimal hardware overhead, and employs LogicNets (DNNs synthesized into LUT logic) to drastically reduce resource usage while enabling ultra-low-latency inference. We integrate this with a differential evolution based exploration and optimization framework to identify high-quality design points. Our results show up to a 10.95x reduction in area and 30% lower latency with little to no loss in fidelity compared to the state-of-the-art. LUNA enables scalable, low-footprint, and high-speed qubit readout, supporting the development of larger and more reliable quantum computing systems. - oai:arXiv.org:2512.07808v1 + Interplay of entanglement structures and stabilizer entropy in spin models + https://arxiv.org/abs/2503.08620 + arXiv:2503.08620v4 Announce Type: replace +Abstract: Understanding the interplay between nonstabilizerness and entanglement is crucial for uncovering the fundamental origins of quantum complexity. Recent studies have proposed entanglement spectral quantities, such as antiflatness of the entanglement spectrum and entanglement capacity, as effective complexity measures, establishing direct connections to stabilizer R\'enyi entropies. In this work, we systematically investigate quantum complexity across a diverse range of spin models, analyzing how entanglement structure and nonstabilizerness serve as distinctive signatures of quantum phases. By studying entanglement spectra and stabilizer entropy measures, we demonstrate that these quantities consistently differentiate between distinct phases of matter. Specifically, we provide a detailed analysis of spin chains including the XXZ model, the transverse-field XY model, its extension with Dzyaloshinskii-Moriya interactions, as well as the Cluster Ising and Cluster XY models. Our findings reveal that entanglement spectral properties and magic-based measures serve as intertwined, robust indicators of quantum phase transitions, highlighting their significance in characterizing quantum complexity in many-body systems. + oai:arXiv.org:2503.08620v4 quant-ph - cs.LG - Tue, 09 Dec 2025 00:00:00 -0500 - new + cond-mat.other + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - M. A. Farooq, G. Di Guglielmo, A. Rajagopala, N. Tran, V. A. Chhabria, A. Arora + Michele Viscardi, Marcello Dalmonte, Alioscia Hamma, Emanuele Tirrito - Fast-feedback protocols for calibration and drift control in quantum computers - https://arxiv.org/abs/2512.07815 - arXiv:2512.07815v1 Announce Type: new -Abstract: We introduce two classes of lightweight, adaptive calibration protocols for quantum computers that leverage fast feedback. The first enables shot-by-shot updates to device parameters using measurement outcomes from simple, indefinite-outcome quantum circuits. This low-latency approach supports rapid tuning of one or more parameters in real time to mitigate drift. The second protocol updates parameters after collecting measurements from definite-outcome circuits (e.g.~syndrome extraction circuits for quantum error correction), balancing efficiency with classical control overheads. We use numerical simulations to demonstrate that both methods can calibrate 1- and 2-qubit gates rapidly and accurately even in the presence of decoherence, state preparation and measurement (SPAM) errors, and parameter drift. We propose and demonstrate effective adaptive strategies for tuning the hyperparameters of both protocols. Finally, we demonstrate the feasibility of real-time in-situ calibration of qubits performing quantum error correction, using only syndrome data, via numerical simulations of syndrome extraction in the [[5,1,3]] code. - oai:arXiv.org:2512.07815v1 + Quantum Glassiness From Efficient Learning + https://arxiv.org/abs/2505.00087 + arXiv:2505.00087v3 Announce Type: replace +Abstract: We show a relation between quantum learning theory and algorithmic hardness. We use the existence of efficient, local learning algorithms for energy estimation -- such as the classical shadows algorithm -- to prove that finding near-ground states of disordered quantum systems exhibiting a certain topological property is impossible in the average case for Lipschitz quantum algorithms. A corollary of our result is that many standard quantum algorithms fail to find near-ground states of these systems, including time-$T$ Lindbladian dynamics from an arbitrary initial state, time-$T$ quantum annealing, phase estimation to $T$ bits of precision, and depth-$T$ variational quantum algorithms, whenever $T$ is less than some universal constant times the logarithm of the system size. To achieve this, we introduce a generalization of the overlap gap property (OGP) for quantum systems that we call the quantum overlap gap property (QOGP). We prove that preparing low-energy states of systems which exhibit the QOGP is intractable for quantum algorithms whose outputs are stable under perturbations of their inputs. We then prove that the QOGP is satisfied for a sparsified variant of the quantum $p$-spin model, giving the first known algorithmic hardness-of-approximation result for quantum algorithms in finding the ground state of a non-stoquastic, noncommuting quantum system. Inversely, we show that the Sachdev--Ye--Kitaev (SYK) model does not exhibit the QOGP, consistent with previous evidence that the model is rapidly mixing at low temperatures. + oai:arXiv.org:2505.00087v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new + cond-mat.dis-nn + cond-mat.stat-mech + math-ph + math.MP + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alicia B. Magann, Nathan E. Miller, Robin Blume-Kohout, Peter Maunz, Kevin C. Young + Eric R. Anschuetz - Comparing quantum channels using Hermitian-preserving trace-preserving linear maps: A physically meaningful approach - https://arxiv.org/abs/2512.07822 - arXiv:2512.07822v1 Announce Type: new -Abstract: In quantum technologies, quantum channels are essential elements for the transmission of quantum states. The action of a quantum channel usually introduces noise in the quantum state and thereby reduces the information contained in it. Concatenating a quantum channel with another quantum channel makes it more noisy and degrades its information and resource preservability. These are mathematically described by completely positive trace-preserving linear maps that represent the generic evolution of quantum systems. These are special cases of Hermitian-preserving trace-preserving linear maps. In this work, we demonstrate a physically meaningful way to compare a pair of quantum channels using Hermitian-preserving trace-preserving linear maps. More precisely, given a pair of quantum channels and an arbitrary unknown input state, we show that if the output state of one quantum channel from the pair can be obtained from the output statistics of the other channel from the pair using some quantum measurement, then the latter channel from the pair can be obtained from the former channel by concatenating it with a Hermitian-preserving trace-preserving linear map. This relation between these two channels is a preorder, and we try to study its characterization in this work. We also illustrate the implications of our results for the incompatibility of quantum devices through an example. - oai:arXiv.org:2512.07822v1 + Verifying Quantum Memory in the Dynamics of Spin Boson Models + https://arxiv.org/abs/2505.13067 + arXiv:2505.13067v2 Announce Type: replace +Abstract: We investigate the nature of memory effects in the non-Markovian dynamics of spin boson models. Local quantum memory criteria can be used to indicate that the reduced dynamics of an open system necessarily requires a quantum memory in its environment. We apply two such criteria, derived from different definitions put forward in the literature, to spin boson and two-spin boson models. For the computation of dynamical maps and process tensors, we employ a numerically exact method for non-Markovian open system dynamics based on matrix product operator influence functionals, that can be applied across broad parameter regimes. We find that, with access to single-intervention process tensors, one can generally predict quantum memory in the dynamics at low temperatures. Given instead only the dynamical map, we are still able to detect quantum memory in the case of resonant environments at short evolution times. Moreover, we confirm quantum memory in the stationary dynamical regime using process tensors with the correlated steady state of system and environment as initial condition. + oai:arXiv.org:2505.13067v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Arindam Mitra, Jatin Ghai + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Charlotte B\"acker, Valentin Link, Walter T. Strunz - The rationality of radical pair mechanism in real biological systems - https://arxiv.org/abs/2512.05974 - arXiv:2512.05974v1 Announce Type: cross -Abstract: The radical pair mechanism (RPM) in the chemical magnetic compass model is considered to be one of the most promising candidates for the avian magnetic navigation, and quantum needle phenomenon further boosts the navigation precision to a new high level. It is well known that there are also a variety of methods in the field of magnetic field sensing in laboratory, e.g. Ramsey protocol of NV centers in diamond. Here, we compare the RPM model and Ramsey-like model under laboratory conditions and under in vivo conditions respectively. The results are both surprising and reasonable. Under laboratory conditions, if we have precise control over time and a reasonably accurate prior knowledge of the magnetic field direction, the Ramsey-like model will outperform the RPM model. However, when such information is unavailable, as under in vivo conditions, the RPM model stands out. The RPM model achieves greater practicality at the cost of reduced accuracy. - oai:arXiv.org:2512.05974v1 - physics.bio-ph + Optimal Phase-Insensitive Force Sensing with Non-Gaussian States + https://arxiv.org/abs/2505.20832 + arXiv:2505.20832v3 Announce Type: replace +Abstract: Quantum metrology enables sensitivity to approach the limits set by fundamental physical laws. Even a single continuous mode offers enhanced precision, with the improvement scaling with its occupation number. Due to their high information capacity, continuous modes allow for the engineering of quantum non-Gaussian states, which not only improve metrological performance but can also be tailored to specific experimental platforms and conditions. Recent advancements in control over continuous platforms operating in the quantum regime have renewed interest in sensing weak forces, also coupling to massive macroscopic objects. In this work, we investigate a force-sensing scheme where a physical process completely randomizes the direction of the induced phase-space displacement, and the unknown force strength is inferred through excitation-number-resolving measurements. We find that $N$-spaced states, where only every $N^{\text{th}}$ Fock state occupation is nonzero, approach the achievable sensing bound. Additionally, non-Gaussian states are shown to be more resilient against decoherence than their Gaussian counterparts with the same occupation number. While Fock states typically offer the best protection against decoherence, we uncover a transition in the metrological landscape -- revealed through a tailored decoherence-aware Fisher-information-based reward functional -- where experimental constraints favor a family of number-squeezed Schr\"odinger cat states. Specifically, by implementing quantum optimal control in a minimal spin-boson system, we identify these states as maximizing force sensitivity under lossy dynamics and finite system controllability. Our results provide a pathway for enhancing force sensing in a variety of continuous quantum systems, ranging from massive systems like mechanical oscillators to massless systems such as quantum light and microwave resonators. + oai:arXiv.org:2505.20832v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Xiaoyu Chen, Haibin Liu, Jianming Cai + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/7pyw-tgjd + Phys. Rev. Lett. 135, 230802 (2025) + Piotr T. Grochowski, Radim Filip - Detuning-insensitive wide-field imaging of vector microwave fields with diamond sensors - https://arxiv.org/abs/2512.05986 - arXiv:2512.05986v1 Announce Type: cross -Abstract: Nitrogen vacancy (NV) centers in diamond have precipitated profound advances in microwave detection, manifesting themselves both in spatial resolution and sensitivity. However, typical methods based on Rabi oscillations are subject to detunings due to thermal and magnetic fluctuations and/or gradients, which introduce systematic errors and render the measurements susceptible to environmental perturbations. Here, we propose and demonstrate a novel approach for determining both the magnitude and direction of microwaves, by exploiting the spectral line broadening effect in the optically detected magnetic resonance of NV centers. This method eliminates the requirement of aligning the MW frequency to the spin transitions and is therefore immune to variations and inhomogeneities of the magnetic field and temperature, providing an optimal tool for fast imaging applications. With this method, we achieved wide-field imaging of near field microwaves generated with a microscale $\rm{\Omega}$-pattern antenna with a resolution of 800\,nm. Combining with the vector detection using multi-axis NVs, a full reconstruction of the vector microwave fields is obtained. Besides, our scheme also exhibits excellent linearity over a broad range of MW amplitudes, and the scale is theoretically calculated to be more than four orders. Our results augment the applicability of diamond-based microwave devices in applications under complex scenarios, especially where large dynamic range, fast test speed, and high spatial resolution are demanded. - oai:arXiv.org:2512.05986v1 - physics.ins-det - cond-mat.mes-hall + Anonymous and private parameter estimation in networks of quantum sensors + https://arxiv.org/abs/2507.01101 + arXiv:2507.01101v2 Announce Type: replace +Abstract: Anonymity and privacy are two key properties of modern communication networks. In quantum networks, distributed quantum sensing has emerged as a powerful use case, with applications to clock synchronisation, detecting gravitational effects and more. In this work, we develop a new protocol that, for the first time, combines the different cryptographic properties of anonymity and privacy for the task of distributed parameter estimation. That is, we present a protocol that allows a selected subset of network participants to anonymously collaborate in estimating the average of their private parameters. Crucially, this is achieved without disclosing either the individual parameter values or the identities of the participants, neither to each other nor to the broader network. + oai:arXiv.org:2507.01101v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Xiu-Qi Chen, Rui-Zhi Zhang, Gang-Qin Liu, Huijie Zheng + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-sa/4.0/ + 10.1103/lbfk-cykl + Phys. Rev. Applied 24, 054053 (2025) + Jarn de Jong, Santiago Scheiner, Naomi R. Solomons, Ziad Chaoui, Damian Markham, Anna Pappa - Semantic Temporal Single-photon LiDAR - https://arxiv.org/abs/2512.06008 - arXiv:2512.06008v1 Announce Type: cross -Abstract: Temporal single-photon (TSP-) LiDAR presents a promising solution for imaging-free target recognition over long distances with reduced size, cost, and power consumption. However, existing TSP-LiDAR approaches are ineffective in handling open-set scenarios where unknown targets emerge, and they suffer significant performance degradation under low signal-to-noise ratio (SNR) and short acquisition times (fewer photons). Here, inspired by semantic communication, we propose a semantic TSP-LiDAR based on a self-updating semantic knowledge base (SKB), in which the target recognition processing of TSP-LiDAR is formulated as a semantic communication. The results, both simulation and experiment, demonstrate that our approach surpasses conventional methods, particularly under challenging conditions of low SNR and limited acquisition time. More importantly, our self-updating SKB mechanism can dynamically update the semantic features of newly encountered targets in the SKB, enabling continuous adaptation without the need for extensive retraining of the neural network. In fact, a recognition accuracy of 89% is achieved on nine types of unknown targets in real-world experiments, compared to 66% without the updating mechanism. These findings highlight the potential of our framework for adaptive and robust target recognition in complex and dynamic environments. - oai:arXiv.org:2512.06008v1 - eess.IV - cs.CV + Deterministic Equations for Feedback Control of Open Quantum Systems + https://arxiv.org/abs/2507.01934 + arXiv:2507.01934v2 Announce Type: replace +Abstract: Feedback control in open quantum dynamics is crucial for the advancement of various coherent platforms. However, currently only a handful of feedback master equations exist in the literature, which are restricted to specific types of feedback. In this letter we first introduce a unifying framework, based on a single general equation, that describes all possible feedback schemes in sequentially (and continuously) measured systems, and from which all previous results follow. Next, we specialize it to the case of quantum jumps and introduce a new type of feedback based on the channel of the last detected jump, as well as the time elapsed since it occurred. Our description is experimentally grounded, and naturally allows for the introduction of realistic effects, such as time-delays in the feedback loop. We illustrate our results with two time-dependent feedback protocols conditioned on quantum-jump detections: one achieving population inversion of a two-level system against a thermal bath, and another enabling real-time reversal of quantum transitions, both admitting steady-state solutions. + oai:arXiv.org:2507.01934v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Fang Li, Tonglin Mu, Shuling Li, Junran Guo, Keyuan Li, Jianing Li, Ziyang Luo, Xiaodong Fan, Ye Chen, Yunfeng Liu, Hong Cai, Lip Ket Chin, Jinbei Zhang, Shihai Sun - - - Quantum, Diplomacy, and Geopolitics - https://arxiv.org/abs/2512.06052 - arXiv:2512.06052v1 Announce Type: cross -Abstract: Quantum technologies -- spanning communication, sensing, computing, and cryptography -- are rapidly emerging as critical paths of geopolitical competition and strategic defence innovation. Unlike traditional technological advances, quantum introduces novel capabilities that fundamentally disrupt established norms of security, intelligence, and diplomatic engagement. This strategic analysis explores the evolving quantum landscape through the dual lenses of diplomacy and geopolitics, with specific implications for defence leaders, policymakers, and industry stakeholders. The benefits and challenges of quantum technologies are examined from a diplomatic and geopolitical perspective to help leaders make informed strategic decisions. Leading powers now recognise quantum as a domain where technological leadership directly translates to geopolitical influence, compelling an intense race for dominance alongside new forms of multilateral diplomacy aimed at managing both risks and opportunities. Quantum technologies do not all have the same operational maturity, but technological progress is accelerating. Post-quantum cryptography demands immediate action -- every encrypted communication created today may be harvested and decrypted within the decade by adversaries equipped with quantum capabilities. - oai:arXiv.org:2512.06052v1 - physics.soc-ph - cs.CY - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Axel Ferrazzini - - - Ferromagnetic Phase Transition of DPPH Induced by a Magic Angle Helical Magnetic Field - https://arxiv.org/abs/2512.06053 - arXiv:2512.06053v1 Announce Type: cross -Abstract: We report the results and unique instrument configuration of a novel experiment in which we successfully transitioned a DPPH sample from its natural paramagnetic state and essentially a non-magnetic material to a ferromagnetic state at room temperature. This was achieved using a specifically applied helical flux magnetic field. The DPPH sample (2,2-diphenyl-1-picrylhydrazyl) remained ferromagnetic for at least one hour after the experiment, indicating that a transformation in the material was induced by the external field rather than being merely a temporary magnetic phase transition observed only during the experiment. The external magnetic field used had a helical pitch angle of approximately $54.7{\deg}$, known mathematically as the Magic Angle, relative to the +z-axis, which is aligned with the normal S to N external field's magnetic moment vector. Based on the phenomenology of the experiment, we infer that this specific magic angle corresponding to the known quantization precession spin angle of free electrons under a homogeneous straight flux magnetic field potentially enhances the percentage of unpaired valence electrons within the DPPH material, allowing them to align in parallel with the applied external field. Typically, in paramagnetic materials, the distribution of unpaired electrons' quantum spins relative to an external field is nearly random, showing roughly a 50% chance of either parallel or antiparallel alignment. Only a slight majority preference exists in one alignment direction due to the Boltzmann thermal distribution, which contributes to the paramagnetic nature of these materials. In our measurements, we found that the induced ferromagnetism of the DPPH sample resulted in an abnormal thousand-fold decimal value increase in relative magnetic permeability at ${\mu}{\approx}1.4$, compared to its typical paramagnetic value of $1.0001$ for this material. - oai:arXiv.org:2512.06053v1 - cond-mat.mtrl-sci - physics.app-ph - physics.ins-det - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Emmanouil Markoulakis, John Chatzakis, Antonios Konstantaras, Iraklis Rigakis, Emmanuel Antonidakis - - - Temporal correlations and chaos from spacetime kernel - https://arxiv.org/abs/2512.06078 - arXiv:2512.06078v1 Announce Type: cross -Abstract: We develop a finite-dimensional formulation of the recently introduced notion of ``timelike entanglement'', defined in terms of two-point functions between operators supported on different Cauchy slices. Using a local orthonormal operator basis, we recast this construction in terms of a generalized response tensor. Building on this, we introduce a generalized spacetime density kernel (GSDK) corresponding to higher-point correlation functions, including time-ordered as well as out-of-time-ordered correlators. We show that the Haar-averaged $(2N)$-point function yields the $(2N)$-th moment of the spectral form factor (SFF), evaluated at an $N$-enhanced effective temperature. The correlation functions of the GSDK operators also yield the SFF, with an effective $(1/N)$-reduction of the physical time-scales. The GSDK places both scrambling diagnostics and spectral statistics on a similar footing and clarifies how higher-point correlators and non-trivial time ordering capture fine-grained dynamical information of a quantum system. - oai:arXiv.org:2512.06078v1 - hep-th - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Rathindra Nath Das, Arnab Kundu, Matheus H. Martins Costa, Nemai Chandra Sarkar - - - Synergistic Computational Approaches for Accelerated Drug Discovery: Integrating Quantum Mechanics, Statistical Thermodynamics, and Quantum Computing - https://arxiv.org/abs/2512.06141 - arXiv:2512.06141v1 Announce Type: cross -Abstract: Accurately predicting protein-ligand binding free energies (BFEs) remains a central challenge in drug discovery, particularly because the most reliable methods, such as free energy perturbation (FEP), are computationally intensive and difficult to scale. Here, we introduce a hybrid quantum-classical framework that combines Mining Minima sampling with quantum mechanically refined ligand partial charges, QM/MM interaction evaluation, and variational quantum eigensolver (VQE)-based electronic energy correction. This design enables explicit treatment of polarization, charge redistribution, and electronic correlation effects that are often underestimated in purely classical scoring schemes, while retaining computational efficiency. Across 23 protein targets and 543 ligands, the method achieves a mean absolute error of about 1.10 kcal/mol with strong rank-order fidelity (Pearson R = 0.75, Spearman rho = 0.76, Kendall tau = 0.57), consistent with the performance of contemporary FEP protocols. Notably, the workflow requires only about 25 minutes per ligand on standard compute resources, resulting in an approximate 20-fold reduction in computational cost relative to alchemical free energy approaches. This level of accuracy and efficiency makes the method well-suited for high-throughput lead optimization and iterative design cycles in pharmaceutical discovery. The framework also provides a natural foundation for future integration with machine learning models to enable predictive, large-scale, and adaptive screening strategies. - oai:arXiv.org:2512.06141v1 - physics.chem-ph - q-bio.QM - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Farzad Molani, Art E. Cho - - - From Mono- to Hexa-Interstitials: Computational Insights into Carbon Defects in Diamond - https://arxiv.org/abs/2512.06167 - arXiv:2512.06167v1 Announce Type: cross -Abstract: We present a comprehensive first-principles investigation of carbon self-interstitial defects in diamond, ranging from mono- to hexa-interstitial complexes. By quantum mechanical density functional theory, empowered by interatomic potential models, we efficiently sample the complex configurational landscape and identify both known and previously unreported defect geometries. Our results reveal a pronounced energetic driving force for aggregation: the formation energy per interstitial decreases systematically from isolated split interstitials to compact multi-interstitial clusters, with the tetra-interstitial platelet emerging as a particularly stable structural motif. Additionally, charge analysis indicates that the predominantly covalent bonding in diamond becomes more polar within the defect centers. Analysis of defect energy levels shows that only the investigated mono-, di-, penta-, and hexa-interstitial complexes introduce in-gap electronic states, whereas the tri- and tetra-interstitial clusters are electronically inert. Vibrational spectroscopies further reveal that self-interstitials generate characteristic signatures. Short carbon-carbon bonds inside the defect cores give rise to high-frequency vibrational modes between 1375 and 1925 cm$^{-1}$, which are strongly IR-active but exhibit weak Raman activity. Taken together, these findings provide a coherent picture of the structural, electronic, and vibrational characteristics of carbon self-interstitials and establish a robust framework for their experimental identification. - oai:arXiv.org:2512.06167v1 - cond-mat.mtrl-sci - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Nima Ghafari Cherati, Arsalan Hashemi, \'Ad\'am Gali - - - MaxwellLink: A unified framework for self-consistent light-matter simulations - https://arxiv.org/abs/2512.06173 - arXiv:2512.06173v1 Announce Type: cross -Abstract: A major challenge in light-matter simulations is bridging the disparate time and length scales of electrodynamics and molecular dynamics. Current computational approaches often rely on heuristic approximations of either the electromagnetic (EM) or material component, hindering the exploration of complex light-matter systems. Herein, MaxwellLink -- a modular, open-source Python framework -- is developed for the massively parallel, self-consistent propagation of classical EM fields interacting with a large heterogeneous molecular ensemble. The package utilizes a robust TCP/UNIX socket interface to couple EM solvers with a wide range of external molecular drivers. This decoupled architecture allows users to seamlessly switch between levels of theory of either the EM solver or molecules without modifying the counterpart. Crucially, MaxwellLink supports EM solvers spanning from single-mode cavities to full-feature three-dimensional finite-difference time-domain (FDTD) engines, and molecules described by multilevel open quantum systems, force-field and first-principles molecular dynamics, and nonadiabatic real-time Ehrenfest dynamics. Benefiting from the socket-based design, the EM engine and molecular drivers scale independently across multiple high-performance computing (HPC) nodes, facilitating large-scale simulations previously inaccessible to existing numerical schemes. The versatility and accuracy of this code are demonstrated through applications including superradiance, radiative energy transfer, vibrational strong coupling in Bragg resonators, and plasmonic heating of molecular gases. By providing a unified, extensible engine, MaxwellLink potentially offers a powerful platform for exploring emerging phenomena across the research fronts of spectroscopy, quantum optics, plasmonics, and polaritonics. - oai:arXiv.org:2512.06173v1 - physics.comp-ph - physics.chem-ph - physics.optics - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xinwei Ji, Andres Felipe Bocanegra Vargas, Gang Meng, Tao E. Li - - - Polarons from first principles - https://arxiv.org/abs/2512.06176 - arXiv:2512.06176v1 Announce Type: cross -Abstract: This article reviews recent theoretical developments in the ab initio study of polarons in materials. The polaron is an emergent quasiparticle that arises from the interaction between electrons and phonons in solids, and consists of an electron or a hole accompanied by a distortion of the crystal lattice. Recent advances in experiments, theory, and computation have made it possible to investigate these quasiparticles with unprecedented detail, reigniting the interest in this classic problem of condensed matter physics. Recent theoretical and computational advances include ab initio calculations of polaron spectral functions, wavefunctions, lattice distortions, and transport and optical properties. These developments provide new insight into polaron physics, but they have evolved somewhat independently from the earlier effective Hamiltonian approaches that laid the foundation of the field. This article aims to bridge these complementary perspectives by placing them within a single unified conceptual framework. To this end, we start by reviewing effective Hamiltonians of historical significance in polaron theory, ab initio techniques based on density functional theory, and many-body first-principles approaches to polarons. After this survey, we outline a general field-theoretic framework that bridges between these diverse approaches to polaron physics. For completeness, we also review recent progress in the study of exciton polarons and self-trapped excitons and their relations to polarons. Beyond the methodology, we discuss recent applications to several classes of materials that attracted attention in the context of polaron physics. - oai:arXiv.org:2512.06176v1 - cond-mat.mtrl-sci - physics.app-ph - physics.comp-ph - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zhenbang Dai, Jon Lafuente-Bartolome, Feliciano Giustino - - - Dispersion Engineering of Planar Sub-millimeter Wave Waveguides and Resonators with Low Radiation Loss - https://arxiv.org/abs/2512.06199 - arXiv:2512.06199v1 Announce Type: cross -Abstract: Mm-wave and THz superconducting circuits find numerous applications in areas ranging from quantum information and sensing to high-energy physics. Planar THz transmission lines and resonators are fabrication-friendly, compact, and scalable, and they can be efficiently interfaced with external signals and controls. However, planar circuits radiate strongly at high frequencies, which precludes their use in loss-sensitive applications. Here, we present the design and characterization of planar dispersion-engineered transmission lines that effectively suppress radiation leakage in desired mm-wave bands. We extend this concept to design planar resonators with extremely low radiation leakage, resulting in radiation Q-factors above 106 at 553 GHz. Low-loss planar THz circuitry will impact many application domains, including broadband communications, quantum information, radio astronomy, and cosmology. - oai:arXiv.org:2512.06199v1 - physics.optics - physics.app-ph - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Furkan Sahbaz, Simeon I. Bogdanov - - - Robust AC vector sensing at zero magnetic field with pentacene - https://arxiv.org/abs/2512.06272 - arXiv:2512.06272v1 Announce Type: cross -Abstract: Quantum sensors based on electronic spins have emerged as powerful probes of microwave-frequency fields. Among other solid-state platforms, spins in molecular crystals offer a range of advantages, from high spin density to functionalization via chemical tunability. Here, we demonstrate microwave vector magnetometry using the photoexcited spin triplet of pentacene molecules, operating at zero external magnetic field and room temperature. We achieve full three-dimensional microwave field reconstruction by detecting the Rabi frequencies of anisotropic spin-triplet transitions associated with two crystallographic orientations of pentacene in deuterated naphthalene crystals. We further introduce a phase alternated protocol that extends the rotating-frame coherence time by an order of magnitude and enables sensitivities of approximately $1~\mu\mathrm{T}/\sqrt{\mathrm{Hz}}$ with sub-micrometer spatial resolution. These results establish pentacene-based molecular spins as a practical and high-performance platform for microwave quantum sensing in addition to demonstrating control techniques broadly applicable to other molecular and solid-state spin systems. - oai:arXiv.org:2512.06272v1 - cond-mat.mes-hall - physics.app-ph - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Boning Li, Garrett Heller, Jungbae Yong, Alexander Ungar, Hao Tang, Guoqing Wang, Patrick Hautle, Yifan Quan, Paola Cappellaro - - - Integrable construction of a two-dimensional lattice model with anisotropic Hubbard couplings - https://arxiv.org/abs/2512.06310 - arXiv:2512.06310v1 Announce Type: cross -Abstract: By defining a graded global R-operator $\mathbb{R}_{ab}^{(2D,2S)}$ that couples free-fermion structures and incorporates anisotropic Hubbard interactions while satisfying the Yang--Baxter equation, we construct a strictly solvable two-dimensional lattice model. We then build the layer-to-layer transfer matrix through a bidirectional-monodromy construction and prove the model's integrability via the associated global RTT relations. Using the nested algebraic Bethe ansatz, we obtain the exact eigenvalues of the transfer matrix and derive the corresponding first- and second-level Bethe equations. Finally, by taking the logarithmic derivative of the transfer matrix at the regular point, we recover explicitly a local Hamiltonian that features anisotropic hopping, an on-site Hubbard interaction, and orbital-coupling contributions. - oai:arXiv.org:2512.06310v1 - nlin.SI - math-ph - math.MP - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ze Tao, Fujun Liu - - - Laser-written reconfigurable photonic integrated circuit directly coupled to a single-photon avalanche diode array - https://arxiv.org/abs/2512.06528 - arXiv:2512.06528v1 Announce Type: cross -Abstract: To date, most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits (PICs) through single-mode optical fibers. This approach presents significant challenges due to the detection complexity, as cryogenic conditions hinder the development of scalable systems. In addition, going towards fully-integrated devices or, at least, removing the optical fibers would be also advantageous to develop compact and cost-efficient solutions featuring a high number of optical modes. This work reports on the direct coupling of a PIC, fabricated by femtosecond laser writing (FLW), and a silicon single-photon avalanche diode (SPAD) array, fabricated in a custom planar technology and compatible with the operation at room temperature. The effectiveness of this solution is shown by achieving perfect coupling and a system detection efficiency as high as 41.0% at a wavelength of 561 nm, which is the highest value reported to date among both heterogeneous/hybrid integrated and directly coupled systems. We also show the robustness of the coupling to misalignments, demonstrating that costly alignment procedures are not needed. Finally, we exploit the SPAD array to characterize a reconfigurable Mach-Zehnder interferometer, i.e., the basic building block of multimode reconfigurable PICs. This solution provides a new avenue to the design and implementation of quantum photonics experiments, especially effective when compact and cost-efficient systems are needed. - oai:arXiv.org:2512.06528v1 - physics.optics - physics.ins-det - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - 10.1038/s41377-025-01854-6 - Light: Science & Applications 14.1 (2025): 199 - Giulio Gualandi, Simone Atzeni, Marco Gardina, Antonino Caime, Giacomo Corrielli, Ivan Labanca, Angelo Gulinatti, Ivan Rech, Roberto Osellame, Giulia Acconcia, Francesco Ceccarelli - - - Geometry-Induced Vacuum Polarization and Mode Shifts in Maxwell-Klein-Gordon Theory - https://arxiv.org/abs/2512.06605 - arXiv:2512.06605v1 Announce Type: cross -Abstract: Geometric confinement is known to modify single-particle dynamics through effective potentials, yet its imprint on the interacting quantum vacuum remains largely unexplored. In this work, we investigate the Maxwell--Klein--Gordon system constrained to curved surfaces and demonstrate that the geometric potential $\Sigma_{\mathrm{geom}}(\mathbf{r})$ acts as a local renormalization environment. We show that extrinsic curvature modifies the scalar loop spectrum, entering the vacuum polarization as a position-dependent mass correction $M^2(\mathbf{r}) \to m^2 + \Sigma_{\mathrm{geom}}(\mathbf{r})$. This induces a finite, gauge-invariant ``geometry-induced running'' of the electromagnetic response. In the long-wavelength regime ($|{\bf Q}|R \ll 1$), we derive a closed-form expression for the relative frequency shift $\Delta\omega/\omega$, governed by the overlap between the electric energy density and the geometric potential. Applying this formalism to Gaussian bumps, cylindrical shells, and tori, we identify distinct spectral signatures that distinguish these quantum loop corrections from classical geometric optics. Our results suggest that spatial curvature can serve as a tunable knob for ``vacuum engineering,'' offering measurable shifts in high-$Q$ cavities and plasmonic systems. - oai:arXiv.org:2512.06605v1 - physics.optics - gr-qc - math-ph - math.MP - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Li Wang, Jun Wang, Yong-Long Wang - - - Quantum Temporal Convolutional Neural Networks for Cross-Sectional Equity Return Prediction: A Comparative Benchmark Study - https://arxiv.org/abs/2512.06630 - arXiv:2512.06630v1 Announce Type: cross -Abstract: Quantum machine learning offers a promising pathway for enhancing stock market prediction, particularly under complex, noisy, and highly dynamic financial environments. However, many classical forecasting models struggle with noisy input, regime shifts, and limited generalization capacity. To address these challenges, we propose a Quantum Temporal Convolutional Neural Network (QTCNN) that combines a classical temporal encoder with parameter-efficient quantum convolution circuits for cross-sectional equity return prediction. The temporal encoder extracts multi-scale patterns from sequential technical indicators, while the quantum processing leverages superposition and entanglement to enhance feature representation and suppress overfitting. We conduct a comprehensive benchmarking study on the JPX Tokyo Stock Exchange dataset and evaluate predictions through long-short portfolio construction using out-of-sample Sharpe ratio as the primary performance metric. QTCNN achieves a Sharpe ratio of 0.538, outperforming the best classical baseline by approximately 72\%. These results highlight the practical potential of quantum-enhanced forecasting model, QTCNN, for robust decision-making in quantitative finance. - oai:arXiv.org:2512.06630v1 - cs.LG - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Chi-Sheng Chen, Xinyu Zhang, Rong Fu, Qiuzhe Xie, Fan Zhang - - - Spurious Strange Correlators in Symmetry-Protected Topological Phases - https://arxiv.org/abs/2512.06691 - arXiv:2512.06691v1 Announce Type: cross -Abstract: Strange correlator is a powerful tool widely used in detecting symmetry-protected topological (SPT) phases. However, the result of strange correlator crucially relies on the adoption of the reference state. In this work, we report that an ill-chosen reference state can induce spurious long-range strange correlators in trivial SPT phases, leading to false positives in SPT diagnosis. Using matrix product state (MPS) representation, we trace the origin of these spurious signals in trivial SPT phases to the magnitude-degeneracy of the transfer matrix. We systematically classify three distinct mechanisms responsible for such degeneracy, each substantiated by concrete examples: (1) the presence of high-dimensional irreducible representations in the entanglement space; (2) a phase mismatch in symmetry representations between the target and reference states; and (3) long-range order arising from symmetry breaking. Our findings clarify the importance of the choice of proper reference states, providing a guideline to avoid pitfalls and correctly identify SPT order using strange correlators. - oai:arXiv.org:2512.06691v1 - cond-mat.str-el - cond-mat.mes-hall - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Wei-Liang Gao, Jie-Yu Zhang, Zheng-Xin Liu, Peng Ye - - - Mitigating Barren plateaus in quantum denoising diffusion probabilistic models - https://arxiv.org/abs/2512.06695 - arXiv:2512.06695v1 Announce Type: cross -Abstract: Quantum generative models leverage quantum superposition and entanglement to enhance learning efficiency for both classical and quantum data. The quantum denoising diffusion probabilistic model (QuDDPM), inspired by its classical counterpart, has been proposed as a promising framework for quantum generative learning. QuDDPM is capable of efficiently learning and generating quantum data, and it demonstrates excellent performance in learning correlated quantum noise models, quantum many-body phases, and the topological structure of quantum data. However, we show that barren plateaus emerge in QuDDPMs due to the use of 2-design states as the input for the denoising process, which severely undermines the performance of QuDDPM. Through theoretical analysis and experimental validation, we confirm the presence of barren plateaus in the original QuDDPM. To address this issue, we introduce an improved QuDDPM that utilizes a distribution maintaining a certain distance from the Haar distribution, ensuring better trainability. Experimental results demonstrate that our approach effectively mitigates the barren plateau problem and generates samples with higher quality, paving the way for scalable and efficient quantum generative learning. - oai:arXiv.org:2512.06695v1 - cs.LG - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Haipeng Cao, Kaining Zhang, Dacheng Tao, Zhaofeng Su - - - Exploring electron spin dynamics in spin chains using defects as a quantum probe - https://arxiv.org/abs/2512.06722 - arXiv:2512.06722v1 Announce Type: cross -Abstract: We investigate the quantum dynamics of the electron spin resonance of topological defects (edge state) in dimerized chains. These objects are discontinuities of the spin chain protected by the properties of the global system leading to a quantum many-body multiplet protected from the environment decoherence. Despite recent achievements in the realization of isolated and finite spin chains, the potential implementation in quantum devices needs the knowledge of the relaxation and decoherence sources. Our study reveals that electron spin lattice relaxation is governed at lowest temperatures by phonon-bottlenecked process and at high temperature by the chain dimerization gap. We show that the inter edge-state effective dipolar field is reduced by the intrachain exchange coupling leading to a longer coherence time than isolated ions at equivalent concentration. Ultimately, we demonstrate that the homogeneous broadening is governed by the intra-chain dipolar field, and we establish design principles for optimizing coherence in future materials. - oai:arXiv.org:2512.06722v1 - cond-mat.str-el - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - L. Soriano, A. Manoj-Kumar, G. Gerbaud, A. Savoyant, R. Dassonneville, H. Vezin, O. Jeannin, M. Orio, M. Fourmigu\'e, S. Bertaina - - - Real-Time Dynamics in Two Dimensions with Tensor Network States via Time-Dependent Variational Monte Carlo - https://arxiv.org/abs/2512.06768 - arXiv:2512.06768v1 Announce Type: cross -Abstract: Reliably simulating two-dimensional many-body quantum dynamics with projected entangled pair states (PEPS) has long been a difficult challenge. In this work, we overcome this barrier for low-energy quantum dynamics by developing a stable and efficient time-dependent variational Monte Carlo (tVMC) framework for PEPS. By analytically removing all gauge redundancies of the PEPS manifold and exploiting tensor locality, we obtain a numerically well-conditioned stochastic reconfiguration (SR) equation amenable to robust solution using the efficient Cholesky decomposition, enabling long-time evolution in previously inaccessible regimes. We demonstrate the power and generality of the method through four representative real-time problems in two dimensions: (I) chiral edge propagation in a free-fermion Chern insulator; (II) fractionalized charge transport in a fractional Chern insulator; (III) vison confinement dynamics in the Higgs phase of a Z2 lattice gauge theory; and (IV) superfluidity and critical velocity in interacting bosons. All simulations are performed on 12x12 or 13x13 lattices with evolution times T = 10 to 12 using modest computational resources (1 to 5 days on a single GPU card). Where exact benchmarks exist (case I), PEPS-tVMC matches free-fermion dynamics with high accuracy up to T = 12. These results establish PEPS-tVMC as a practical and versatile tool for real-time quantum dynamics in two dimensions. The method extends the reach of classical tensor-network simulations for studying elementary excitations in quantum many-body systems and provides a valuable computational counterpart to emerging quantum simulators. - oai:arXiv.org:2512.06768v1 - cond-mat.str-el - cond-mat.stat-mech - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Yantao Wu - - - Controllable Emergence of Multiple Topological Anderson Insulator Phases in Photonic Su-Schrieffer-Heeger Lattices - https://arxiv.org/abs/2512.06851 - arXiv:2512.06851v1 Announce Type: cross -Abstract: We investigate the emergence and control of multiple topological Anderson insulator (TAI) phases in a one-dimensional Su-Schrieffer-Heeger (SSH) waveguide lattice with generalized Bernoulli-type disorder introduced in the intradimer couplings. By systematically varying the disorder configuration -- including the values and probabilities of the multivariate distribution -- we demonstrate that both the number and width of TAI phases can be precisely engineered. Analytical determination of topological phase boundaries via the inverse localization length shows excellent agreement with numerical simulations. Our results reveal a rich landscape of disorder-induced topological phase transitions, including multiple reentrant TAI phases that arise as the disorder amplitude increases. Furthermore, we show that the mean chiral displacement serves as a sensitive probe for detecting these topological transitions, providing a practical route for experimental realization in photonic waveguide lattices. This work establishes a versatile framework for designing quantum and photonic materials with customizable topological properties driven by tailored disorder. - oai:arXiv.org:2512.06851v1 - physics.optics - cond-mat.dis-nn - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Ruijiang Ji, Yunbo Zhang, Shu Chen, Zhihao Xu - - - Statistical structural properties of many-body chaotic eigenfunctions and applications - https://arxiv.org/abs/2512.07016 - arXiv:2512.07016v1 Announce Type: cross -Abstract: In this paper, we employ a semiperturbative theory to study the statistical structural properties of energy eigenfunctions (EFs) in many-body quantum chaotic systems consisting of a central system coupled to an environment. Under certain assumptions, we derive both the average shape and the statistical fluctuations of EFs on the basis formed by the direct product of the energy eigenbases of the system and the environment. Furthermore, we apply our results to two fundamental questions: (i) the properties of the reduced density matrix of the central system in an eigenstate, and (ii) the structure of the off-diagonal smooth function within the framework of the eigenstate thermalization hypothesis. Numerical results are also presented in support of our main findings. - oai:arXiv.org:2512.07016v1 - cond-mat.stat-mech - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Wen-ge Wang, Qingchen Li, Jiaozi Wang, Xiao Wang - - - The Fine-Structure Constant as a Scaled Quantity - https://arxiv.org/abs/2512.07027 - arXiv:2512.07027v1 Announce Type: cross -Abstract: The fine-structure constant alpha approximately 1/137 is traditionally regarded as a fundamental dimensionless parameter. I argue instead that alpha is a scaled quantity that arises only where the structural scales contributed by classical electromagnetism (e), quantum mechanics (h-bar), and special relativity (c) intersect. None of these theories, taken individually, supplies the independent scales required to define alpha. The constant first appears when relativistic corrections are added to the Schrodinger-Bohr description of hydrogen (Sommerfeld), and it becomes the structural coupling in quantum electrodynamics, where quantum and relativistic effects modify the classical electromagnetic interaction. Expressing the governing laws in canonical form reveals this dependence and eliminates representational artifacts that make alpha appear fundamental. The running of alpha in QED further demonstrates its status as a scale-dependent coupling rather than a universal constant. I conclude that alpha is a domain-specific structural ratio reflecting contingent relationships among independent physical scales. - oai:arXiv.org:2512.07027v1 - physics.hist-ph - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Harry Sticker - - - Local Reversibility and Divergent Markov Length in 1+1-D Directed Percolation - https://arxiv.org/abs/2512.07220 - arXiv:2512.07220v1 Announce Type: cross -Abstract: Recent progress in open many-body quantum systems has highlighted the importance of the Markov length, the characteristic scale over which conditional correlations decay. It has been proposed that non-equilibrium phases of matter can be defined as equivalence classes of states connected by short-time evolution while maintaining a finite Markov length, a notion called local reversibility. A natural question is whether well-known classical models of non-equilibrium criticality fit within this framework. Here we investigate the Domany--Kinzel model -- which exhibits an active phase and an absorbing phase separated by a 1+1-D directed-percolation transition -- from this information-theoretic perspective. Using tensor network simulations, we provide evidence for local reversibility within the active phase. Notably, the Markov length diverges upon approaching the critical point, unlike classical equilibrium transitions where Markov length is zero due to their Gibbs character. Correspondingly, the conditional mutual information exhibits scaling consistent with directed percolation universality. Further, we analytically study the case of 1+1-D compact directed percolation, where the Markov length diverges throughout the phase diagram due to spontaneous breaking of domain-wall parity symmetry from strong to weak. Nevertheless, the conditional mutual information continues to faithfully detect the corresponding phase transition. - oai:arXiv.org:2512.07220v1 - cond-mat.stat-mech - cond-mat.soft - cond-mat.str-el - nlin.CG - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Yu-Hsueh Chen, Tarun Grover - - - Multiplet structure of chromium(III) dopants in wide band gap materials - https://arxiv.org/abs/2512.07398 - arXiv:2512.07398v1 Announce Type: cross -Abstract: Transition metal doping is commonly used for altering the properties of solid-state materials to suit applications in science and technology. Partially filled $d$-shells of transition metal atoms lead to electronic states with diverse spatial and spin symmetries. Chromium(III) cations have shown great potential for designing laser materials and, more recently, for developing spin qubits in quantum applications. They also represent an intriguing class of chemical systems with strongly correlated multi-reference excited states, due to the $d^3$ electron configuration. These states are difficult to describe accurately using single-reference quantum chemical methods such as density functional theory (DFT), the most commonly used method to study the electronic structures of solid-state systems. Recently, the periodic effective Hamiltonian of crystal field (pEHCF) method has been shown to overcome some limitations arising in the calculations of excited $d$-states. In this work, we assess the suitability of DFT and pEHCF to calculate the electronic structure and $d$-$d$ excitations of chromium(III) dopants in wide band gap host materials. The results will aid computational development of novel transition metal-doped materials and provide a deeper understanding of the complex nature of transition metal dopants in solids. - oai:arXiv.org:2512.07398v1 - cond-mat.mtrl-sci - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Ilya Popov, Petros-Panagis Filippatos, Shayantan Chaudhuri, Andrei L. Tchougr\'eeff, Katherine Inzani, Elena Besley - - - Anomalous Wave-Packet Dynamics in One-Dimensional Non-Hermitian Lattices - https://arxiv.org/abs/2512.07484 - arXiv:2512.07484v1 Announce Type: cross -Abstract: Non-Hermitian (NH) systems have attracted great attention due to their exotic phenomena beyond Hermitian domains. Here we study the wave-packet dynamics in general one-dimensional NH lattices and uncover several unexpected phenomena. The group velocity of a wave packet during the time evolution in such NH lattices is not only governed by the real part of the band structure but also by its imaginary part. The momentum also evolves due to the imaginary part of the band structure, which can lead to a self-induced Bloch oscillation in the absence of external fields. Furthermore, we discover the wave-packet dynamics can exhibit disorder-free NH jumps even when the energy spectra are entirely real. Finally, we show that the NH jumps can lead to both positive and negative temporal Goos--H\"{a}nchen shifts at the edge. - oai:arXiv.org:2512.07484v1 - physics.optics - cond-mat.dis-nn - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yanyan He, Tomoki Ozawa - - - Site-controlled quantum dot arrays edge-coupled to integrated silicon nitride waveguides and devices - https://arxiv.org/abs/2512.07535 - arXiv:2512.07535v1 Announce Type: cross -Abstract: The scalability of quantum photonic integrated circuits opens the path towards large-scale quantum computing and communication. To date, this scalability has been limited by the stochastic nature of the quantum light sources. Moreover, hybrid integration of different platforms will likely be necessary to combine state-of-the-art devices into a functioning architecture. Here, we demonstrate the active alignment and edge-coupling of arrays of ten site-controlled gallium arsenide quantum dots to an array of ten silicon nitride single-mode waveguides, at cryogenic temperatures. The coupling is facilitated by the fabrication of nanopillars, deterministically self-aligned around each quantum dot, leading to a high-yield and regular array of single-photon sources. An on-chip beamsplitter verifies the triggered emission of single photons into the silicon nitride chip. The low inhomogeneous broadening of the ensemble enables us to observe the spectral overlap of adjacent site-controlled emitters. Across the array of waveguides, the signal collected from each coupled quantum dot is consistently and reproducibly 0.17 relative to the free-space collection from the very same single-photon source. Comparing measurement with waveguide simulations, we infer that absolute coupling efficiencies of $\approx 5 \%$ are currently obtained between our quantum dots and the waveguides. - oai:arXiv.org:2512.07535v1 - physics.optics - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - John O'Hara, Nicola Maraviglia, Mack Johnson, Jesper H{\aa}kansson, Salvador Medina, Gediminas Juska, Luca Colavecchi, Frank H. Peters, Brian Corbett, Emanuele Pelucchi - - - Tensor Network Fluid Simulations in Structured Domains Using the Lattice Boltzmann Method - https://arxiv.org/abs/2512.07615 - arXiv:2512.07615v1 Announce Type: cross -Abstract: High-fidelity fluid simulations are central to understanding transport phenomena, yet resolving large or geometrically complex systems remains computationally prohibitive with existing methods. Here we introduce a tensor-network formulation of the lattice Boltzmann method based on matrix product states (MPS), commonly known as a quantum-inspired approach, enabling compressed representations of structured flow fields with inherent error control. We demonstrate the generality of the method on flows through structured media and complex vascular geometries, establishing for the first time that tensor-network techniques can efficiently resolve fluid dynamics in complex, irregular domains. We show that in the presence of translational or approximate symmetries of the geometry, fluid states exhibit low effective complexity in MPS form, yielding compression ratios exceeding two orders of magnitude while preserving physical structure and dynamical fidelity. This reduction enables systematic numerical exploration of regimes that were previously intractable. Our results position tensor networks as a scalable paradigm for continuum mechanics. - oai:arXiv.org:2512.07615v1 - physics.flu-dyn - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Lukas Gross, David M. Wawrzyniak, Josef M. Winter, Nikolaus A. Adams, Elie Mounzer - - - Mesoscopic superfluid to superconductor transition - https://arxiv.org/abs/2512.07632 - arXiv:2512.07632v1 Announce Type: cross -Abstract: Spectrum tomography for the energy ($E$) of a ring-shaped Bose-Hubbard circuit is illustrated. There is an inter-particle interaction $U$ that controls superfluidity (SF) and the transition to the Mott Insulator (MI) regime. The circuit is coupled to an electromagnetic cavity mode of frequency $\omega_0$, and the coupling is characterized by a generalized fine-structure-constant $\alpha$ that controls the emergence of superconductivity (SC). The ${(U,\alpha,\omega_0,E)}$ diagram features SF and SC regions, a vast region of fragmented possibly chaotic states, and an MI regime for large $U$. The mesoscopic version of the Meissner effect and the Anderson-Higgs mechanism are discussed. - oai:arXiv.org:2512.07632v1 - cond-mat.mes-hall - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yehoshua Winsten, Doron Cohen - - - Robustness of flat band superconductivity against disorder in a two-dimensional Lieb lattice model - https://arxiv.org/abs/2512.07648 - arXiv:2512.07648v1 Announce Type: cross -Abstract: Recently, the possibility of high-temperature superconductivity (SC) in flat-band (FB) systems has been the focus of a great deal of activity. This study reveals that unlike conventional intra-band SC for which disorder has a dramatic impact, that associated with FBs is surprisingly robust to disorder-induced fluctuations and quasi-particle localization. In particular, for weak off-diagonal disorder, the critical temperature decreases linearly with disorder amplitude for conventional SC, whereas it is only quadratic in the case of SC in FBs. Our findings could have a major impact on the research and development of new compounds whose high purity will no longer be a critical barrier to their synthesis. - oai:arXiv.org:2512.07648v1 - cond-mat.supr-con - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - 10.1103/PhysRevB.111.L020506 - Georges Bouzerar, Maxime Thumin - - - Grand Canonical vs Canonical Krylov Complexity in Double-Scaled Complex SYK Model - https://arxiv.org/abs/2512.07715 - arXiv:2512.07715v1 Announce Type: cross -Abstract: We consider the complex SYK model in the double-scaling limit. We obtain the transfer matrix for the grand canonical ensemble and symmetrize it. In the (n,Q)- basis of chord states, the grand canonical transfer matrix is block diagonal, where each block is the canonical transfer matrix for the respective charge sector. We therefore conclude that the Krylov complexity for the grand canonical ensemble is given by the sum of the complexities in the charge sectors weighted by a probability function that depends on the chemical potential. Finally, we compute the Krylov complexity analytically in the limit of early and late time in the charge sector and numerically for both canonical and grand canonical ensemble. - oai:arXiv.org:2512.07715v1 - hep-th - cond-mat.str-el - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Stefan Forste, Yannic Kruse, Saurabh Natu - - - Trapped Fermions Through Kolmogorov-Arnold Wavefunctions - https://arxiv.org/abs/2512.07800 - arXiv:2512.07800v1 Announce Type: cross -Abstract: We investigate a variational Monte Carlo framework for trapped one-dimensional mixture of spin-$\frac{1}{2}$ fermions using Kolmogorov-Arnold networks (KANs) to construct universal neural-network wavefunction ans\"atze. The method can, in principle, achieve arbitrary accuracy, limited only by the Monte Carlo sampling and was checked against exact results at sub-percent precision. For attractive interactions, it captures pairing effects, and in the impurity case it agrees with known results. We present a method of systematic transfer learning in the number of network parameters, allowing for efficient training for a target precision. We vastly increase the efficiency of the method by incorporating the short-distance behavior of the wavefunction into the ans\"atz without biasing the method. - oai:arXiv.org:2512.07800v1 - nucl-th - cond-mat.dis-nn - cond-mat.quant-gas - physics.comp-ph - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Paulo F. Bedaque, Jacob Cigliano, Hersh Kumar, Srijit Paul, Suryansh Rajawat - - - Nonlinear Quantum Mechanics and Artificial Intelligence - https://arxiv.org/abs/2512.07809 - arXiv:2512.07809v1 Announce Type: cross -Abstract: We examine a criterion for relativistic covariance of nonlinear quantum field theory recently proposed by GPT-5 and published in Physics Letters B. We show that this criterion inadvertently tests a different property -- locality of the Hamiltonian -- and is insensitive to whether the theory is nonlinear. We recall the correct criterion, identified by Gisin and Polchinski thirty-five years ago, and reformulate their result in field-theoretic language. - oai:arXiv.org:2512.07809v1 - hep-th - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jonathan Oppenheim - - - Distributing Graph States Across Quantum Networks - https://arxiv.org/abs/2009.10888 - arXiv:2009.10888v4 Announce Type: replace -Abstract: Graph states are an important class of multipartite entangled quantum states. We propose a new approach for distributing graph states across a quantum network. We consider a quantum network consisting of nodes-quantum computers within which local operations are free-and EPR pairs shared between nodes that can continually be generated. We prove upper bounds for our approach on the number of EPR pairs consumed, number of timesteps taken, and amount of classical communication required, all of which are equal to or better than that of prior work. We also reduce the problem of minimizing the number of timesteps taken to distribute a graph state using our approach to a network flow problem having polynomial time complexity. - oai:arXiv.org:2009.10888v4 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1109/QCE52317.2021.00049 - Alex Fischer, Don Towsley - - - Finite-Key Analysis of Quantum Key Distribution with Characterized Devices Using Entropy Accumulation - https://arxiv.org/abs/2203.06554 - arXiv:2203.06554v2 Announce Type: replace -Abstract: The Entropy Accumulation Theorem (EAT) was introduced to significantly improve the finite-size rates for device-independent quantum information processing tasks such as device-independent quantum key distribution (QKD). A natural question would be whether it also improves the rates for device-dependent QKD. In this work, we provide an affirmative answer to this question. We present new tools for applying the EAT in the device-dependent setting. We present sufficient conditions for the Markov chain conditions to hold as well as general algorithms for constructing the needed min-tradeoff function. Utilizing Dupuis' recent privacy amplification without smoothing result, we improve the key rate by optimizing the sandwiched R\'{e}nyi entropy directly rather than considering the traditional smooth min-entropy. We exemplify these new tools by considering several examples including the BB84 protocol with the qubit-based version and with a realistic parametric downconversion source, the six-state four-state protocol and a high-dimensional analog of the BB84 protocol. - oai:arXiv.org:2203.06554v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Ian George, Jie Lin, Thomas van Himbeeck, Kun Fang, Norbert L\"utkenhaus - - - Correlation as a Resource in Unitary Quantum Measurements - https://arxiv.org/abs/2212.03829 - arXiv:2212.03829v3 Announce Type: replace -Abstract: Quantum measurement is a physical process. What physical resources and constraints does quantum mechanics require for measurement to produce the classical world we observe? Treating measurement as a fully unitary quantum process, our goal is to show that objective, redundant, and correctly aligned outcomes are possible iff the environment begins in a specially structured, correlated subspace. We start with a minimal set of assumptions: unitarity, orthogonality of conditional environment branches, and finite-dimensional Hilbert spaces. Using these, we demonstrate that generic environmental states cannot support redundant and mutually consistent records of the signal, the measured quantum system. The admissible initial states form a subspace on which the measurement maps obey the Knill-Laflamme error-correction conditions, revealing that the emergence of classical objectivity relies on the environment behaving like a quantum error-correcting code. The post-measurement subspace naturally factorizes into a ``pointer'' to hold measurement outcomes and ``memory'' to retain pre-measurement quantum information about the environment's state, thereby respecting the no-deletion theorem. This further allows the identification of correlation as a finite resource consumed during measurement. Through an explicit qudit model with local interactions, we demonstrate how correlated environments yield redundant observer networks. Simulations show that record fidelity and redundancy depend on the initial correlations in the environment. This perspective links quantum Darwinism to error correction and raises the possibility that natural processes may prepare and evolutionarily favour environments capable of supporting reliable measurement. - oai:arXiv.org:2212.03829v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Vishal Johnson (Max Planck Institute for Astrophysics Garching, Ludwig-Maximilians-Universit\"at M\"unchen), Ashmeet Singh (Indian Institute of Technology Delhi), Reimar Leike (Max Planck Institute for Astrophysics Garching), Philipp Frank (Max Planck Institute for Astrophysics Garching), Torsten En{\ss}lin (Max Planck Institute for Astrophysics Garching, Deutsches Zentrum f\"ur Astrophysik, G\"orlitz, Ludwig-Maximilians-Universit\"at M\"unchen, Excellence Cluster ORIGINS Garching) - - - One-Shot Distributed Source Simulation: As Quantum as it Can Get - https://arxiv.org/abs/2301.04301 - arXiv:2301.04301v3 Announce Type: replace -Abstract: Distributed source simulation is the task where two (or more) parties share some correlated randomness and use local operations and no communication to convert this into some target correlation. Wyner's seminal result showed that asymptotically the rate of uniform shared randomness needed for this task is given by a mutual information induced measure, now referred to as Wyner's common information. This asymptotic result was extended by Hayashi in the quantum setting to separable states, the largest class of states for which this task can be performed to vanishing error. In this work we characterize this task in a near-tight manner in the one-shot setting using the smooth entropy framework. We do this by introducing one-shot operational quantities and correlation measures that characterize them. We establish asymptotic equipartition properties for our correlation measures thereby recovering the previous vanishing-error asymptotic results. In doing so, we consider technical points in one-shot network information theory and provide methods for cardinality bounds in the smooth entropy calculus. We also introduce entangled state versions of the distributed source simulation task and determine bounds in this setting via quantum embezzling. This provides a strong characterization of this network task in the one-shot, quantum regime. - oai:arXiv.org:2301.04301v3 - quant-ph - cs.IT - math.IT - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1109/TIT.2025.3624812 - IEEE Transactions on Information Theory, vol. 71, no. 12, pp. 9251 - 9284, Oct 2025 - Ian George, Min-Hsiu Hsieh, Eric Chitambar - - - A Robust Large-Period Discrete Time Crystal and its Signature in a Digital Quantum Computer - https://arxiv.org/abs/2309.11560 - arXiv:2309.11560v5 Announce Type: replace -Abstract: Discrete time crystals (DTCs) are novel out-of-equilibrium quantum states of matter which break time translational symmetry. DTCs have been extensively realized in experiments, particularly their subclass that is characterized by period-doubling dynamics due to its natural occurrence in a system of periodically driven two-level, e.g., spin-1/2, particles. The realization of DTCs beyond period-doubling, including their generalizations termed discrete quasicrystals has also been made in recent years, though such experiments typically involve higher spin particles. Constructing and observing DTCs beyond period-doubling in systems of two-level particles are generally still considered an open challenge due to the latter's $\mathbb{Z}_2$ symmetry that natively only leads to period-doubling. In this work, we developed an intuitive interacting system of two-level particles (qubits) that supports the more non-trivial period-quadrupling DTCs ($4T$-DTCs). Remarkably, by utilizing a variational algorithm, we are able to observe clear signatures of such $4T$-DTCs in a quantum processor despite the presence of considerable noise and the small number of available qubits. Our findings extend the landscape of time crystalline behavior by demonstrating a distinct realization of time crystallinity beyond standard period-doubling dynamics with qubits (two-level particles) on a NISQ-era digital quantum computer, as well as the potential of existing noisy intermediate-scale quantum devices for simulating exotic non-equilibrium quantum states of matter. - oai:arXiv.org:2309.11560v5 - quant-ph - cond-mat.mes-hall - cond-mat.str-el - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Tianqi Chen, Ruizhe Shen, Ching Hua Lee, Bo Yang, Raditya Weda Bomantara - - - Asymptotic implementation of multipartite quantum channels and other quantum instruments using local operations and classical communication - https://arxiv.org/abs/2310.05362 - arXiv:2310.05362v3 Announce Type: replace -Abstract: We prove a necessary condition that a quantum channel on a multipartite system may be approximated arbitrarily closely using local operations and classical communication (LOCC). We then extend those arguments to obtain a condition that applies to all quantum instruments, which range from the most refined case, a generalized measurement, to the most coarse-grained, which is a quantum channel. We illustrate these results by a detailed analysis of a quantum instrument that is known not to be implementable by LOCC, but which can be arbitrarily closely approximated within that framework. As one outgrowth of this analysis, we find a quantum measurement that falls into the same category: it cannot be implemented exactly by LOCC, but can be approximated by LOCC arbitrarily closely. This measurement has an infinite number of outcomes, leaving open the question as to whether or not there exists a measurement within this same category but having only a finite number of outcomes. - oai:arXiv.org:2310.05362v3 - quant-ph - math-ph - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Scott M. Cohen - - - Robust entanglement buffers based on SWAP interactions - https://arxiv.org/abs/2312.05099 - arXiv:2312.05099v2 Announce Type: replace -Abstract: Quantum entanglement is the essential resource for quantum communication and distributed information processing in a quantum network. However, the remote generation over a network suffers from inevitable transmission loss and other technical difficulties. This paper introduces the concept of entanglement buffers as a potential primitive for preparing long-distance entanglement. We investigate the filling of entanglement buffers with either one Bell state or a stream of Bell states via SWAP interactions. We illustrate their resilience to imperfect interactions, noise, and losses, making the buffers suitable for a realistic quantum network scenario. Additionally, larger entanglement buffers can always enhance these benefits. - oai:arXiv.org:2312.05099v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.1088/2058-9565/adf2d7 - Quantum Sci. Technol. 10 04LT01 (2025) - Ye-Chao Liu, Otfried G\"uhne, Stefan Nimmrichter - - - Efficient and high-performance routing of lattice-surgery paths on three-dimensional lattice - https://arxiv.org/abs/2401.15829 - arXiv:2401.15829v3 Announce Type: replace -Abstract: Encoding logical qubits with surface codes and performing multi-qubit logical operations with lattice surgery is one of the most promising approaches to demonstrate fault-tolerant quantum computing. Thus, a method to efficiently schedule a sequence of lattice-surgery operations is vital for high-performance fault-tolerant quantum computing. A possible strategy to improve the throughput of lattice-surgery operations is splitting a large instruction into several small instructions such as Bell state preparation and measurements and executing a part of them in advance. However, scheduling methods to fully utilize this idea have yet to be explored. In this paper, we propose a fast and high-performance scheduling algorithm for lattice-surgery instructions leveraging this strategy. We achieved this by converting the scheduling problem of lattice-surgery instructions to a graph problem of embedding 3D paths into a 3D lattice, which enables us to explore efficient scheduling by solving path search problems in the 3D lattice. Based on this reduction, we propose a method to solve the path-finding problems, look-ahead Dijkstra projection. We numerically show that this method reduced the execution time of benchmark programs generated from quantum phase estimation algorithms by 3.8 times compared with a naive method based on greedy algorithms. Our study establishes the relation between the lattice-surgery scheduling and graph search problems, which leads to further theoretical analysis on compiler optimization of fault-tolerant quantum computing. - oai:arXiv.org:2401.15829v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kou Hamada, Yasunari Suzuki, Yuuki Tokunaga - - - Self-Testing Graph States Permitting Bounded Classical Communication - https://arxiv.org/abs/2404.03496 - arXiv:2404.03496v3 Announce Type: replace -Abstract: Self-testing identifies quantum states and correlations that exhibit nonlocality, distinguishing them, up to local transformations, from other quantum states. Due to their strong nonlocality, it is known that all graph states can be self-tested in the standard setting - where parties are not allowed to communicate. Recently it has been shown that graph states display nonlocal correlations even when bounded classical communication on the underlying graph is permitted, a feature that has found applications in proving a circuit-depth separation between classical and quantum computing. In this work, we develop self testing in the framework of bounded classical communication, and we show that certain graph states can be robustly self-tested even allowing for communication. In particular, we provide an explicit self-test for the circular graph state and the honeycomb cluster state - the latter known to be a universal resource for measurement based quantum computation. Since communication generally obstructs self-testing of graph states, we further provide a procedure to robustly self-test any graph state from larger ones that exhibit nonlocal correlations in the communication scenario. - oai:arXiv.org:2404.03496v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Uta Isabella Meyer, Ivan \v{S}upi\'c, Fr\'ed\'eric Grosshans, Damian Markham - - - Cross-platform certification of the qubit space with a minimal number of parameters - https://arxiv.org/abs/2404.06792 - arXiv:2404.06792v3 Announce Type: replace -Abstract: We demonstrate a determinant dimension witness of a qubit space. Our test has a minimal number of independent parameters. We achieve it by mapping the Bloch sphere $\pi/2$-rotation axis angle on the non-planar so-called Viviani curve. We ran our test on different platforms: IBM Quantum, IQM Resonance, and IonQ. Our investigations show that numerous qubits, especially from the newest IBM Heron family devices, fail the test by more than ten standard deviations. The nature of those deviations has no simple explanation as the test is robust against common imperfections. - oai:arXiv.org:2404.06792v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.1038/s41598-025-27248-7 - Sci. Rep. 15, 43201 (2025) - Tomasz Rybotycki, Tomasz Bia{\l}ecki, Josep Batle, Jakub Tworzyd{\l}o, Adam Bednorz - - - Preparing matrix product states via fusion: constraints and extensions - https://arxiv.org/abs/2404.16360 - arXiv:2404.16360v3 Announce Type: replace -Abstract: In the era of noisy, intermediate-scale quantum (NISQ) devices, the efficient preparation of many-body resource states is a task of paramount importance. In this paper we focus on the deterministic preparation of matrix-product states (MPS) in constant depth by utilizing measurements and classical communication to fuse smaller states into larger ones. We place strong constraints on the MPS that can be prepared using this method, which we refer to as MPS fusion. Namely, we establish that it is necessary for the MPS to have a flat entanglement spectrum. Using the recently introduced split-index MPS (SIMPS) representation, we then introduce a family of states that belong to interesting phases of matter protected by non-onsite symmetries, including anomalous and non-invertible symmetries, and also serve as resources for long-range quantum teleportation, but which lie beyond the scope of ordinary MPS fusion. It is shown constructively that these states can be prepared in constant depth using a broader class of measurement-assisted protocols, which we dub SIMPS fusion. Even in cases when MPS fusion is possible, using SIMPS fusion can give rise to significantly reduced resource overhead. We also discuss constraints on SIMPS fusion and propose a general framework for fusion that encompasses the MPS and SIMPS protocols. Our results therefore simultaneously establish the boundaries of conventional MPS fusion and push the envelope of which states can be prepared using measurement-assisted protocols. - oai:arXiv.org:2404.16360v3 - quant-ph - cond-mat.str-el - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - David T. Stephen, Oliver Hart - - - Exploiting many-body localization for scalable variational quantum simulation - https://arxiv.org/abs/2404.17560 - arXiv:2404.17560v4 Announce Type: replace -Abstract: Variational quantum algorithms (VQAs) represent a promising pathway toward achieving practical quantum advantage on near-term hardware. Despite this promise, for generic, expressive ans\"atze, their scalability is critically hindered by barren plateaus--regimes of exponentially vanishing gradients. We demonstrate that initializing a hardware-efficient, Floquet-structured ansatz within the many-body localized (MBL) phase mitigates barren plateaus and enhances algorithmic trainability. Through analysis of the inverse participation ratio, entanglement entropy, and a novel low-weight stabilizer R\'enyi entropy, we characterize a distinct MBL-thermalization transition. Below a critical kick strength, the circuit avoids forming a unitary 2-design, exhibits robust area-law entanglement, and maintains non-vanishing gradients. Leveraging this MBL regime facilitates the efficient variational preparation of ground states for several model Hamiltonians with significantly reduced computational resources. Crucially, experiments on a 127-qubit superconducting processor provide evidence for the preservation of trainable gradients in the MBL phase for a kicked Heisenberg chain, validating our approach on contemporary noisy hardware. Our findings position MBL-based initialization as a viable strategy for developing scalable VQAs and motivate broader integration of localization into quantum algorithm design. - oai:arXiv.org:2404.17560v4 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Chenfeng Cao, Yeqing Zhou, Swamit Tannu, Nic Shannon, Robert Joynt - - - Multiple quantum exceptional, diabolical, and hybrid points in multimode bosonic systems: I. Inherited and genuine singularities - https://arxiv.org/abs/2405.01666 - arXiv:2405.01666v2 Announce Type: replace -Abstract: The existence and degeneracies of quantum exceptional, diabolical, and hybrid (i.e., diabolically degenerated exceptional) singularities of simple bosonic systems composed of up to five modes with damping and/or amplification are analyzed. Their dynamics governed by quadratic non-Hermitian Hamiltonians is followed using the Heisenberg-Langevin equations. Their dynamical matrices generally exhibit specific structures that allow for an effective reduction of their dimension by half. This facilitates analytical treatment and enables efficient spectral analysis based on characteristic second-order diabolical degeneracies. Conditions for the observation of inherited quantum hybrid points, observed directly in the dynamics of field operators, having up to third-order exceptional and second-order diabolical degeneracies are revealed. Surprisingly, exceptional degeneracies of only second and third orders are revealed, even though the systems with up to five modes are considered. Exceptional and diabolical genuine points and their degeneracies observed in the dynamics of second-order field-operator moments are also analyzed. Each analyzed bosonic system exhibits its own unique and complex dynamical behavior. - oai:arXiv.org:2405.01666v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Kishore Thapliyal, Jan Pe\v{r}ina Jr., Grzegorz Chimczak, Anna Kowalewska-Kud{\l}aszyk, Adam Miranowicz - - - Non-Abelian Self-Correcting Quantum Memory and Transversal Non-Clifford Gate beyond the $n^{1/3}$ Distance Barrier - https://arxiv.org/abs/2405.11719 - arXiv:2405.11719v5 Announce Type: replace -Abstract: We construct a family of infinitely many new candidate non-Abelian self-correcting topological quantum memories in $D\geq 5+1$ spacetime dimensions without particle excitations using local commuting non-Pauli stabilizer lattice models and field theories of $\mathbb{Z}_2^3$ higher-form gauge fields with nontrivial topological action. We call such non-Pauli stabilizer models magic stabilizer codes. The family of topological orders have Abelian electric excitations and non-Abelian magnetic excitations that obey Ising-like fusion rules and non-Abelian braiding, including Borromean ring type braiding which is a signature of non-Abelian topological order, generalizing the dihedral group $\mathbb{D}_8$ gauge theory in (2+1)D. The simplest example includes a new non-Abelian self-correcting memory in (5+1)D with Abelian loop excitations and non-Abelian membrane excitations. We prove the self-correction property and the thermal stability, and devise a probabilistic local cellular-automaton decoder. We also construct fault-tolerant non-Clifford CCZ logical gate using constant depth circuit from higher cup products in the 5D non-Abelian code. The use of higher-cup products and non-Pauli stabilizers allows us to get an $O(n^{2/5})$ distance overcoming the $O(n^{1/3})$ distance barrier in conventional topological stabilizer codes, including the 3D color code and the 6D self-correcting color code. - oai:arXiv.org:2405.11719v5 - quant-ph - cond-mat.str-el - hep-th - math.QA - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Po-Shen Hsin, Ryohei Kobayashi, Guanyu Zhu - - - Detailed assessment of calculating drag force with quantum computers: Explicit time-evolution precludes exponential advantage for nonlinear differential equations - https://arxiv.org/abs/2406.06323 - arXiv:2406.06323v3 Announce Type: replace -Abstract: This study examines the potential for fault-tolerant quantum computers to provide utility in fluid dynamics simulations, with a focus on drag force calculations for ship hull design. We assess whether quantum algorithms can surpass classical computational limits by generating detailed quantum resource estimates (QREs) in terms of logical qubits and $T$-gate counts. Our analysis is based on a quantum algorithm leveraging Carleman linearization of the lattice Boltzmann method (LBM), which has been suggested to offer exponential speedup. We develop efficient block encodings for LBM matrices and a method for amplitude-encoding drag force. We apply the method to the simple case of fluid flow past a sphere across a range of Reynolds numbers ($\mathrm{Re}$). We estimate the required (logical qubits)$\times$($T$-gates), finding them to be prohibitively large, ranging from $10^{21}$ to $10^{39}$. While classical simulations scale as $O(\mathrm{Re}^3)$, our QREs exhibit a modest polynomial scaling of $O(\mathrm{Re}^{2.68})$, indicating no exponential quantum advantage. We attribute this limitation to an intrinsic power-law relationship between spatial grid resolution and time-stepping requirements that is a fundamental characteristic of explicit methods for evolving nonlinear differential equations. Thus, quantum computers are unlikely to provide utility in applications that require time-evolving fluids and other systems of nonlinear differential equations. - oai:arXiv.org:2406.06323v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - John Penuel, Amara Katabarwa, Peter D. Johnson, Parker Kuklinski, Benjamin Rempfer, Collin Farquhar, Yudong Cao, Michael C. Garrett - - - Recovering optimal precision in quantum sensing with time domain imperfections - https://arxiv.org/abs/2409.04223 - arXiv:2409.04223v5 Announce Type: replace -Abstract: Quantum control plays a crucial role in enhancing precision scaling for quantum sensing. However, most existing protocols require perfect control, even though real-world devices inevitably have control imperfections. Here, we consider a fundamental setting of quantum sensing with time domain imperfections, where the duration of control pulses and the interrogation time are all subject to uncertainty. Under this scenario, we investigate the task of frequency estimation in the presence of a non-Markovian environment. We design a control strategy and prove that it outperforms any control-free strategies, recovering the optimal Heisenberg limit up to a small error term that is intrinsic to this model. We further demonstrate the advantage of our control strategy via experiments on a nuclear magnetic resonance (NMR) platform. Our finding confirms that the advantage of quantum control in quantum sensing persists even in the presence of imperfections. - oai:arXiv.org:2409.04223v5 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/xbrk-357g - Physical Review A 112, L030401 (2025) - Zi-Shen Li, Xinyue Long, Xiaodong Yang, Dawei Lu, Yuxiang Yang - - - Beating the Optimal Verification of Entangled States via Collective Strategies - https://arxiv.org/abs/2410.00554 - arXiv:2410.00554v3 Announce Type: replace -Abstract: In the realm of quantum information processing, the efficient characterization of entangled states poses an overwhelming challenge, rendering the traditional methods including quantum tomography unfeasible and impractical. To tackle this problem, we propose a new verification scheme using collective strategies, showcasing arbitrarily high efficiency that beats the optimal verification with global measurements. Our collective scheme can be implemented in various experimental platforms and scalable for large systems with a linear scaling on hardware requirement, and distributed operations are allowed. Notably, larger ensembles can always improve the efficiency further, but without increasing the quantum memory. More importantly, the approach consumes only a few copies of the entangled states, while ensuring the preservation of unmeasured ones, and even boosting their fidelity for any subsequent tasks. Furthermore, our protocol provides additional insight into the specific types of noise affecting the system, thereby facilitating potential targeted improvements. These advancements hold promise for a wide range of applications, offering a pathway towards more robust and efficient quantum information processing. - oai:arXiv.org:2410.00554v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.1103/6yrh-9tzp - Phys. Rev. A 112, L060401 (2025) - Ye-Chao Liu, Jiangwei Shang - - - Compressing multivariate functions with tree tensor networks - https://arxiv.org/abs/2410.03572 - arXiv:2410.03572v2 Announce Type: replace -Abstract: Tensor networks are a compressed format for multi-dimensional data. One-dimensional tensor networks -- often referred to as tensor trains (TT) or matrix product states (MPS) -- are increasingly being used as a numerical ansatz for continuum functions by ``quantizing'' the inputs into discrete binary digits. Here we demonstrate the power of more general tree tensor networks for this purpose. We provide direct constructions of a number of elementary functions as generic tree tensor networks and interpolative constructions for more complicated functions via a generalization of the tensor cross interpolation algorithm. For a range of multi-dimensional functions we show how more structured tree tensor networks offer a significantly more efficient ansatz than the commonly used tensor train. We demonstrate an application of our methods to solving multi-dimensional, non-linear Fredholm equations, providing a rigorous bound on the rank of the solution which, in turn, guarantees exponentially scaling accuracy with the size of the tree tensor network for certain problems. - oai:arXiv.org:2410.03572v2 - quant-ph - cs.NA - math.NA - physics.comp-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Joseph Tindall, E. Miles Stoudenmire, Ryan Levy - - - Disentangling magic states with classically simulable quantum circuits - https://arxiv.org/abs/2410.09001 - arXiv:2410.09001v3 Announce Type: replace -Abstract: We show that states obtained from deep random Clifford circuits doped with non-Clifford phase gates (including T-gates and $\sqrt{\mathrm{T}}$-gates) can be disentangled completely, provided the number of non-Clifford gates is smaller or approximately equal to the number of qubits. This implies that Pauli expectation values of such states can be efficiently simulated classically, despite them exhibiting both extensive entanglement and extensive nonstabilizerness. We prove this result analytically using a quantum error correction formulation, demonstrate its applicability numerically, and discuss consequences for the disentanglability of states generated through Hamiltonian dynamics. We show that this result implies a novel representation of approximate state designs that can also facilitate their efficient generation, and we propose a novel quantum circuit compression scheme for Clifford circuits doped with non-Clifford phase gates. - oai:arXiv.org:2410.09001v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.1103/ggp1-byj1 - Gerald E. Fux, Benjamin B\'eri, Rosario Fazio, Emanuele Tirrito - - - Maneuvering measurement-coherence into measurement-entanglement - https://arxiv.org/abs/2410.20793 - arXiv:2410.20793v3 Announce Type: replace -Abstract: Quantum dynamics governs the transformation of static quantum resources, such as coherence and entanglement, in both quantum states and measurements. Prior studies have established that a quantum channel's state-cohering power can be converted into the state-entangling power without additional coherence. Here, we complete this coherence-to-entanglement paradigm by demonstrating that a channel's measurement-cohering power can likewise be converted into the measurement-entangling power. This result reinforces, on the dynamical level, the intuition that entanglement emerges as a manifestation of coherence. To formalize this picture, we develop resource theories for measurement-cohering and measurement-entangling powers and characterize the structure of incoherent measurements to analyze measurement-coherence generation. Furthermore, we show that the state-cohering power of a quantum channel is equivalent to the measurement-cohering power of its adjoint map, and a corresponding equivalence also exists between the state-entangling power and the measurement-entangling power. - oai:arXiv.org:2410.20793v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Ho-Joon Kim, Soojoon Lee - - - LEGO_HQEC: A Software Tool for Analyzing Holographic Quantum Codes - https://arxiv.org/abs/2410.22861 - arXiv:2410.22861v2 Announce Type: replace -Abstract: Quantum error correction (QEC) is a crucial prerequisite for future large-scale quantum computation. Finding and analyzing new QEC codes, along with efficient decoding and fault-tolerance protocols, is central to this effort. Holographic codes are a recent class of QEC subsystem codes derived from holographic bulk/boundary dualities. In addition to exploring the physics of such dualities, these codes possess useful QEC properties such as tunable encoding rates, distance scaling competitive with topological codes, and excellent recovery thresholds. To allow for a comprehensive analysis of holographic code constructions, we introduce LEGO_HQEC, a software package utilizing the quantum LEGO formalism. This package constructs holographic codes on regular hyperbolic tilings and generates their stabilizer generators and logical operators for a specified number of seed codes and layers. Three decoders are included: an erasure decoder based on Gaussian elimination; an integer-optimization decoder; and a tensor-network decoder. With these tools, LEGO_HQEC thus enables future systematic studies regarding the utility of holographic codes for practical quantum computing. - oai:arXiv.org:2410.22861v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Junyu Fan, Matthew Steinberg, Alexander Jahn, Chunjun Cao, Aritra Sarkar, Sebastian Feld - - - Extendibility of Brauer states - https://arxiv.org/abs/2411.04597 - arXiv:2411.04597v2 Announce Type: replace -Abstract: We investigate the extendibility problem for Brauer states, focusing on the symmetric two-sided extendibility and the de Finetti extendibility. By employing the representation theory of the unitary and orthogonal groups, we provide a general recipe for determining the set of $(n,m)$-extendible and $n$-de Finetti-extendible Brauer states. From the concrete form of the commutant of the diagonal action of the orthogonal group, we explicitly determine the set of parameters for which the Brauer states are $(1,2)$-, $(1,3)$- and $(2,2)$-extendible in any dimension $d$ and find that Brauer states extend with a non-trivial trade-off in $n$ and $m$. Using the same recipe we also provide an estimate of the set of $(1,m)$-extendible Brauer states for any $m$ and dimension $d$. Finally, using the branching rules from $\mathrm{U}(d)$ to $\mathrm{O}(d)$, we obtain the set of $n$-de Finetti-extendible Brauer states in any dimension, and also analytically describe the $n\to\infty$ limiting shape which turns out not to be a polygon for odd dimensions. - oai:arXiv.org:2411.04597v2 - quant-ph - math-ph - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Adrian Solymos, D\'avid Jakab, Zolt\'an Zimbor\'as - - - Information geometry of bosonic Gaussian thermal states - https://arxiv.org/abs/2411.18268 - arXiv:2411.18268v2 Announce Type: replace -Abstract: Bosonic Gaussian thermal states form a fundamental class of states in quantum information science. This paper explores the information geometry of these states, focusing on characterizing the distance between two nearby states and the geometry induced by a parameterization in terms of their mean vectors and Hamiltonian matrices. In particular, for the family of bosonic Gaussian thermal states, we derive expressions for their Fisher-Bures, Kubo-Mori, and $\alpha$-$z$ information matrices with respect to their mean vectors and Hamiltonian matrices. An important application of our formulas consists of fundamental limits on how well one can estimate these parameters. We additionally establish formulas for the derivatives and the symmetric logarithmic derivatives of bosonic Gaussian thermal states. The former could have applications in gradient descent algorithms for quantum machine learning when using bosonic Gaussian thermal states as an ansatz, and the latter in formulating optimal strategies for single parameter estimation of bosonic Gaussian thermal states. Finally, the expressions for the aforementioned information matrices could have additional applications in natural gradient descent algorithms when using bosonic Gaussian thermal states as an ansatz. - oai:arXiv.org:2411.18268v2 - quant-ph - cs.IT - hep-th - math-ph - math.IT - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zixin Huang, Mark M. Wilde - - - Ion-Trap Chip Architecture Optimized for Implementation of Quantum Error-Correcting Code - https://arxiv.org/abs/2501.15200 - arXiv:2501.15200v2 Announce Type: replace -Abstract: We propose a scalable trapped-ion quantum-computing architecture that efficiently incorporates quantum error correction. The chip design exploits orthogonal qubit connectivity by assigning horizontal trap regions to transversal logical gates and vertical regions to non-transversal gates and syndrome extraction, thereby enabling universal gate operations with minimal ion shuttling and reduced hardware complexity. Using a dedicated software tool, we evaluate the architecture on several benchmark algorithms and scheduling policies for two-dimensional color code of varying code distance. Our results demonstrate that increasing the code distance by two reduces the effective logical two-qubit gate error probability by approximately two orders of magnitude, reaching values as low as $10^{-8}$ with the $[[31, 1, 7]]$ color code. This improvement substantially expands the range of algorithms that can be executed reliably, up to scales of a few thousand logical qubits, depending on the algorithmic structure. Overall, these findings validate the practicality and scalability of the proposed architecture and its control strategies, highlighting a viable route toward fault-tolerant, trapped-ion quantum computing. - oai:arXiv.org:2501.15200v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Jeonghoon Lee, Hyeongjun Jeon, Taehyun Kim - - - Nonclassical nullifiers for quantum hypergraph states - https://arxiv.org/abs/2502.02226 - arXiv:2502.02226v2 Announce Type: replace -Abstract: Quantum hypergraph states form a generalisation of the graph state formalism that goes beyond the pairwise (dyadic) interactions imposed by remaining inside the Gaussian approximation. Networks of such states are able to achieve universality for continuous variable measurement based quantum computation with only Gaussian measurements. For normalised states, the simplest hypergraph states are formed from $k$-adic interactions among a collection of $k$ harmonic oscillator ground states. However such powerful resources have not yet been observed in experiments and their robustness and scalability have not been tested. Here we develop and analyse necessary criteria for hypergraph nonclassicality based on simultaneous nonlinear squeezing in the nullifiers of hypergraph states. We put forward an essential analysis of their robustness to realistic scenarios involving thermalisation or loss and suggest several basic proof-of-principle options for experiments to observe nonclassicality in hypergraph states. - oai:arXiv.org:2502.02226v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Abhijith Ravikumar, Darren W. Moore, Radim Filip - - - Observation of quantum free fall and the consistency with the equivalence principle - https://arxiv.org/abs/2502.14535 - arXiv:2502.14535v4 Announce Type: replace -Abstract: The unification of quantum theory and the general theory of relativity - describing gravity, is one of the most important challenges in science. Einstein's general theory of relativity is based on the principle of equivalence, and has been confirmed to great accuracy for large bodies. However, in the quantum domain the equivalence principle has been predicted to take a unique form involving a gauge phase, equal to the quantum phase of a free-falling object. To measure this phase, we realize a novel cold-atom interferometer in which one wave-packet stays static in the laboratory frame while the other is in free fall. The observed relative-phase of the wave-packets confirms the predicted phase of a free-falling object, and shows that in our low energy regime, the equivalence principle may be applied to the quantum domain. Our observation constitutes a fundamental test of the interface between quantum theory and gravity. The new interferometer also opens the door for further probing of the latter interface, as well as to searches for new physics. - oai:arXiv.org:2502.14535v4 - quant-ph - cond-mat.quant-gas - gr-qc - hep-th - physics.atom-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Or Dobkowski, Barak Trok, Peter Skakunenko, Yonathan Japha, David Groswasser, Maxim Efremov, Chiara Marletto, Ivette Fuentes, Roger Penrose, Vlatko Vedral, Wolfgang P. Schleich, Ron Folman - - - A Superconducting Qubit-Resonator Quantum Processor with Effective All-to-All Connectivity - https://arxiv.org/abs/2503.10903 - arXiv:2503.10903v3 Announce Type: replace -Abstract: In this work we introduce a superconducting quantum processor architecture that uses a transmission-line resonator to implement effective all-to-all connectivity between six transmon qubits. This architecture can be used as a test-bed for algorithms that benefit from high connectivity. We show that the central resonator can be used as a computational element, which offers the flexibility to encode a qubit for quantum computation or to utilize its bosonic modes which further enables quantum simulation of bosonic systems. To operate the quantum processing unit (QPU), we develop and benchmark the qubit-resonator conditional Z gate and the qubit-resonator MOVE operation. The latter allows for transferring a quantum state between one of the peripheral qubits and the computational resonator. We benchmark the QPU performance and achieve a genuinely multi-qubit entangled Greenberger-Horne-Zeilinger (GHZ) state over all six qubits with a readout-error mitigated fidelity of $0.86$. - oai:arXiv.org:2503.10903v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Michael Renger, Jeroen Verjauw, Nicola Wurz, Amin Hosseinkhani, Caspar Ockeloen-Korppi, Wei Liu, Aniket Rath, Manish J. Thapa, Florian Vigneau, Elisabeth Wybo, Ville Bergholm, Chun Fai Chan, B\'alint Csat\'ari, Saga Dahl, Rakhim Davletkaliyev, Rakshyakar Giri, Daria Gusenkova, Hermanni Heimonen, Tuukka Hiltunen, Hao Hsu, Eric Hyypp\"a, Joni Ikonen, Tyler Jones, Shabeeb Khalid, Seung-Goo Kim, Miikka Koistinen, Anton Komlev, Janne Kotilahti, Vladimir Kukushkin, Julia Lamprich, Alessandro Landra, Lan-Hsuan Lee, Tianyi Li, Per Liebermann, Sourav Majumder, Janne M\"antyl\"a, Fabian Marxer, Arianne Meijer - van de Griend, Vladimir Milchakov, Jakub Mro\.zek, Jayshankar Nath, Tuure Orell, Miha Papi\v{c}, Matti Partanen, Alexander Plyushch, Stefan Pogorzalek, Jussi Ritvas, Pedro Figueroa Romero, Ville Sampo, Marko Sepp\"al\"a, Ville Selinmaa, Linus Sundstr\"om, Ivan Takmakov, Brian Tarasinski, Jani Tuorila, Olli Tyrkk\"o, Alpo V\"alimaa, Jaap Wesdorp, Ping Yang, Liuqi Yu, Johannes Heinsoo, Antti Veps\"al\"ainen, William Kindel, Hsiang-Sheng Ku, Frank Deppe - - - Bridging wire and gate cutting with ZX-calculus - https://arxiv.org/abs/2503.11494 - arXiv:2503.11494v4 Announce Type: replace -Abstract: Quantum circuit cutting refers to a series of techniques that allow one to partition a quantum computation on a large quantum computer into several quantum computations on smaller devices. This usually comes at the price of a sampling overhead, that is quantified by the $1$-norm of the associated decomposition. The applicability of these techniques relies on the possibility of finding decompositions of the ideal, global unitaries into quantum operations that can be simulated onto each sub-register, which should ideally minimize the $1$-norm. In this work, we show how these decompositions can be obtained diagrammatically using ZX-calculus expanding on the work of Ufrecht et al. [arXiv:2302.00387]. The central idea of our work is that since in ZX-calculus only connectivity matters, it should be possible to cut wires in ZX-diagrams by inserting known decompositions of the identity in standard quantum circuits. We show how, using this basic idea, many of the gate decompositions known in the literature can be re-interpreted as an instance of wire cuts in ZX-diagrams. Furthermore, we obtain improved decompositions for multi-qubit controlled-Z (MCZ) gates with $1$-norm equal to $3$ for any number of qubits and any partition, which we argue to be optimal. Our work gives new ways of thinking about circuit cutting that can be particularly valuable for finding decompositions of large unitary gates. Besides, it sheds light on the question of why exploiting classical communication decreases the 1-norm of a wire cut but does not do so for certain gate decompositions. In particular, using wire cuts with classical communication, we obtain gate decompositions that do not require classical communication. - oai:arXiv.org:2503.11494v4 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Marco Schumann, Tobias Stollenwerk, Alessandro Ciani - - - Logical entanglement distribution between distant 2D array qubits - https://arxiv.org/abs/2503.14894 - arXiv:2503.14894v2 Announce Type: replace -Abstract: Sharing logical entangled pairs between distant quantum nodes is a key process to achieve fault tolerant quantum computation and communication. However, there is a gap between current experimental specifications and theoretical requirements for sharing logical entangled states while improving experimental techniques. Here, we propose an efficient logical entanglement distribution protocol based on surface codes for two distant 2D qubit array with nearest-neighbor interaction. A notable feature of our protocol is that it allows post-selection according to error estimations, which provides the tunability between the infidelity of logical entanglements and the success probability of the protocol. With this feature, the fidelity of encoded logical entangled states can be improved by sacrificing success rates. We numerically evaluated the performance of our protocol and the trade-off relationship, and found that our protocol enables us to prepare logical entangled states while improving fidelity in feasible experimental parameters. We also discuss a possible physical implementation using neutral atom arrays to show the feasibility of our protocol. - oai:arXiv.org:2503.14894v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Yuya Maeda, Yasunari Suzuki, Toshiki Kobayashi, Takashi Yamamoto, Yuuki Tokunaga, Keisuke Fujii - - - Entanglement recycling in two-step port-based teleportation - https://arxiv.org/abs/2504.00710 - arXiv:2504.00710v3 Announce Type: replace -Abstract: A protocol involving the repetitive (twofold, to be precise) application of PBT protocol to the same resource is studied. The quantities characterizing the resulting protocol, so-called \textit{two-step PBT}, namely \textit{enatnglement fidelity} and \textit{success probability} are provided for two scenarios, relying on application of pretty-good measurement, i.e. deterministic and probabilistic PBT with non-EPR resource. This results show that two-step PBT is an accurate protocol, provided the resource is sufficiently large. In particular, the deterministic two-step PBT obtains fidelity that is remarkably close to the optimal MPBT fidelity for teleportation of two quantum states. Additionally, the \textit{recycling fidelity}, i.e. the quantity characterizing the degradation of the resource state is calculated for repetitive application of probabilistic protocol, for both EPR and optimized resource, showing that entanglement recycling with two-step PBT is possible in the former case as well. - oai:arXiv.org:2504.00710v3 - quant-ph - math-ph - math.MP - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Piotr Kopszak, Dmitry Grinko, Adam Burchardt, Maris Ozols, Micha{\l} Studzi\'nski, Marek Mozrzymas + Alberto J. B. Rosal, Patrick P. Potts, Gabriel T. Landi - Q-Cluster: Quantum Error Mitigation Through Noise-Aware Unsupervised Learning - https://arxiv.org/abs/2504.10801 - arXiv:2504.10801v2 Announce Type: replace -Abstract: Quantum error mitigation (QEM) is critical in reducing the impact of noise in the pre-fault-tolerant era, and is expected to complement error correction in fault-tolerant quantum computing (FTQC). In this paper, we propose a novel QEM approach, Q-Cluster, that uses unsupervised learning (clustering) to reshape the measured bit-string distribution. Our approach starts with a simplified bit-flip noise model. It first performs clustering on noisy measurement results, i.e., bit-strings, based on the Hamming distance. The centroid of each cluster is calculated using a qubit-wise majority vote. Next, the noisy distribution is adjusted with the clustering outcomes and the bit-flip error rates using Bayesian inference. Our simulation results show that Q-Cluster can mitigate high noise rates (up to 40% per qubit) with the simple bit-flip noise model. However, real quantum computers do not fit such a simple noise model. To address the problem, we (a) apply Pauli twirling to tailor the complex noise channels to Pauli errors, and (b) employ a machine learning model, ExtraTrees regressor, to estimate an effective bit-flip error rate using a feature vector consisting of machine calibration data (gate & measurement error rates), circuit features (number of qubits, numbers of different types of gates, etc.) and the shape of the noisy distribution (entropy). Our experimental results show that our proposed Q-Cluster scheme improves the fidelity by a factor of 1.46x, on average, compared to the unmitigated output distribution, for a set of low-entropy benchmarks on five different IBM quantum machines. Our approach outperforms the state-of-art QEM approaches M3 [24], Hammer [35], and QBEEP [33] by 1.29x, 1.47x, and 2.65x, respectively. - oai:arXiv.org:2504.10801v2 + Quantum Power Iteration Unified Using Generalized Quantum Signal Processing + https://arxiv.org/abs/2507.11142 + arXiv:2507.11142v2 Announce Type: replace +Abstract: We propose a unifying framework for the state preparation using quantum power method algorithms based on generalized quantum signal processing (GQSP). We apply GQSP to realize quantum analogs of classical power iteration, power Lanczos, inverse iteration, and folded spectrum methods, all within a single coherent framework. GQSP allows efficient realization of methods that require complex polynomials, while avoiding the limitations of approaches based on linear combinations of time-evolution operators. Our constructions, including a Trotter-decomposition-free quantum inverse iteration, achieve near-optimal query scaling, together with reduced qubit requirements. The same formalism yields a quantum folded spectrum method for excited state preparation that avoids explicitly forming powers of the Hamiltonian or performing variational optimization. We provide a theoretical analysis of success probabilities and resource scaling, and we validate the methods numerically using molecular Hamiltonians. The results show that quantum power Lanczos lowers the computational cost and provides robust convergence compared to naive quantum power iteration. Our findings reveal that GQSP-based implementations of power methods combine scalability, flexibility, and robust convergence, paving the way for practical initial state preparations on fault-tolerant quantum devices. + oai:arXiv.org:2507.11142v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1109/QCE65121.2025.00097 - 2025 IEEE International Conference on Quantum Computing and Engineering (QCE), Albuquerque, NM, USA, 2025, pp. 849-860 - Hrushikesh Pramod Patil, Dror Baron, Huiyang Zhou + Viktor Khinevich, Yasunori Lee, Nobuyuki Yoshioka, Wataru Mizukami - Room-temperature hybrid 2D-3D quantum spin system for enhanced magnetic sensing and many-body dynamics - https://arxiv.org/abs/2504.10815 - arXiv:2504.10815v2 Announce Type: replace -Abstract: Advances in hybrid quantum systems and their precise control are pivotal for developing advanced quantum technologies. Two-dimensional (2D) materials with optically accessible spin defects have emerged as a promising platform for building integrated quantum spin systems due to their exceptional flexibility and scalability. However, experimentally realizing such systems and demonstrating their superiority remains challenging. Here, we present a hybrid spin system operating under ambient conditions, integrating boron vacancy (V_B^-) spins in 2D hexagonal boron nitride flakes with a single nitrogen vacancy (NV) center in 3D single-crystal diamonds. This combined system achieves full controllability and exhibits enhanced performance for nanoscale magnetic sensing, including an improved dynamic range. Moreover, we investigate the rich many-body spin dynamics within the hybrid system, which enables us to estimate the concentration of V_B^- spins. This work provides a critical foundation for advancing the development of 2D-3D integrated quantum spin systems. - oai:arXiv.org:2504.10815v2 + Simple ways of preparing qudit Dicke states + https://arxiv.org/abs/2507.13308 + arXiv:2507.13308v2 Announce Type: replace +Abstract: Dicke states are permutation-invariant superpositions of qubit computational basis states, which play a prominent role in quantum information science. We consider here two higher-dimensional generalizations of these states: $SU(2)$ spin-$s$ Dicke states and $SU(d)$ Dicke states. We present various ways of preparing both types of qudit Dicke states on a qudit quantum computer, using two main approaches: a deterministic approach, based on exact canonical matrix product state representations; and a probabilistic approach, based on quantum phase estimation. The quantum circuits are explicit and straightforward, and are arguably simpler than those previously reported. + oai:arXiv.org:2507.13308v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1038/s41534-025-01152-4 - npj Quantum Inf (2025) - Haoyu Sun, Pei Yu, Xu Zhou, Xiangyu Ye, Mengqi Wang, Zhaoxin Liu, Yuhang Guo, Wenzhao Liu, You Huang, Pengfei Wang, Fazhan Shi, Kangwei Xia, Ya Wang + Noah B. Kerzner, Federico Galeazzi, Rafael I. Nepomechie - Dressed Interference in Giant Superatoms: Entanglement Generation and Transfer - https://arxiv.org/abs/2504.12942 - arXiv:2504.12942v2 Announce Type: replace -Abstract: We introduce the concept of giant superatoms (GSAs), where two or more interacting atoms are nonlocally coupled to a waveguide through one of them, and explore their unconventional quantum dynamics. For braided GSAs, this setup enables decoherence-free transfer and swapping of their internal entangled states. For separate GSAs, engineering coupling phases leads to state-dependent chiral emission, which enables selective, directional quantum information transfer. This mechanism further facilitates remote generation of W-class entangled states. Our results thereby open exciting possibilities for quantum networks and quantum information processing. - oai:arXiv.org:2504.12942v2 + Correlation Enhanced Autonomous Quantum Battery Charging via Structured Reservoirs + https://arxiv.org/abs/2508.18086 + arXiv:2508.18086v3 Announce Type: replace +Abstract: In this work, we investigate the autonomous charging process of a quantum battery coupled to a structured reservoir composed of two qubits, each in thermal equilibrium with its own bosonic bath. Moreover, the reservoir interacts with a charger-battery architecture through three configurations: (I) direct coupling between reservoir qubits and battery, (II) collective coupling among the reservoir qubits, charger, and battery, while (III) reflects a collective coupling between the reservoir qubits and charger together with a local charger-battery interaction. However, by using incoherent and coherent initial states, we analyze the stored energy, ergotropy, and charging power of battery, where we derive the upper and lower bounds on the extractable work in terms of the free energy of coherence and correlations exchanged between subsystems. Our results show that global and local coherences, as well as total correlations act as quantum resources that enhance autonomous charging. Additionally, we demonstrate that the free energy stored in the quantum battery splits into contributions from coherence and correlations, providing numerical evidence that supports the derived ergotropy bounds. Importantly, this work highlights how structured reservoirs enable autonomous and resource-enhanced quantum battery operation. + oai:arXiv.org:2508.18086v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1103/crzs-k718 - Physical Review Letters 135, 233601 (2025) - Lei Du, Xin Wang, Anton Frisk Kockum, Janine Splettstoesser + Achraf Khoudiri, Abderrahim El Allati, Youssef Khlifi, Khadija El Anouz, \"Ozg\"ur E. M\"ustecapl{\i}o\u{g}lu - Heterogeneously error-corrected QRAMs - https://arxiv.org/abs/2504.21687 - arXiv:2504.21687v2 Announce Type: replace -Abstract: Quantum Random Access Memory (QRAM) holds the promise of enabling several large scale applications of quantum computers. However, designing fault tolerant QRAMs for large scale applications is still an open problem due to the poor error and resource scaling of current architectures. Existing protocols often overlook the need for error correcting QRAMs, which will be required for data-intensive, fault-tolerant applications. However, naively error correcting all qubits used to implement the QRAM is prohibitively resource intensive, quickly becoming infeasible for large applications. To fill this gap, we propose a novel QRAM architecture that leverages variable strength error correction. We strongly error-correct qubits that heavily influence query fidelity, and lightly correct less critical regions of the QRAM. This scheme produces queries with fidelity bounded by a constant for arbitrarily sized QRAMs without requiring improvements in physical hardware. Furthermore, the heterogeneous scheme requires 5x fewer resources (for depth 30 QRAM) and quadratically slower error scaling as compared to a uniformly error corrected Bucket Brigade QRAM. In this work, we present a rigorous analysis of the query fidelity scaling and perform resource analyses of two variations of the heterogeneous architecture using the surface code. We verify our results using numerical simulations and compare our results against several other existing QRAM techniques. Through our results, we quantitatively prove the optimal scaling of the heterogeneous architecture, paving a way for data-intensive and fault tolerant quantum applications. - oai:arXiv.org:2504.21687v2 + Emergence of non-Markovian Decoherent Histories in Integrable Environment: A "Tape Recorder" Model for Local Quantum Observables + https://arxiv.org/abs/2509.00845 + arXiv:2509.00845v2 Announce Type: replace +Abstract: We propose a new approach to coarse-grained description of quantum evolution that provides an explicit recipe to construct and evaluate multi-time decoherent histories in a controlled way, applicable to non-Markovian and integrable systems. Specifically, we study local interaction quench of a local degree of freedom (an open quantum system) within a noninteracting integrable environment. This setting allows us to identify the environmental degrees of freedom that irreversibly store records of the system's past. These modes emerge sequentially in time and define the projectors required for decoherent histories. We show numerically that the off-diagonal elements of the decoherence functional are exponentially suppressed relative to a significance threshold. + oai:arXiv.org:2509.00845v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Ansh Singal, Kaitlin N. Smith + Nataliya Arefyeva, Evgeny Polyakov - Bound-like State in a 1D Self-Similar Delta-Barrier Array - https://arxiv.org/abs/2505.01317 - arXiv:2505.01317v2 Announce Type: replace -Abstract: We investigate a one-dimensional quantum system with a self-similar arrangement of delta-function potential barriers, exhibiting discrete scale invariance. The singular potential induces kinematically enforced symmetry breaking at $x=0$, decoupling the positive and negative spatial regions and leading to non-symmetric zero-energy states. We demonstrate that the system supports a unique zero-energy wavefunction, which, though not square-integrable, decays to zero at infinity and acts as a bound-like state with self-similar properties under discrete scaling transformations, akin to Efimov physics but limited to a single state. In momentum space, this wavefunction exhibits a threshold singularity at low momenta, with behavior depending on the scaling exponent $\alpha$:power-law divergence and log-periodic modulations for $0 < \alpha < 1$, logarithmic divergence for $\alpha = 1$, and a finite limit for $\alpha > 1$, which may be observable through time-of-flight or spectroscopic measurements in cold atom experiments. The system's continuous spectrum, starting at zero energy, lacks discrete bound states. These findings highlight the role of singular potentials in generating scale-invariant quantum phenomena and provide a minimal framework for studying discrete scale symmetry and its potential experimental signatures. - oai:arXiv.org:2505.01317v2 + Toward Axion Signal Extraction in Semiconductor Spin Qubits Via Spectral Engineering + https://arxiv.org/abs/2509.06791 + arXiv:2509.06791v3 Announce Type: replace +Abstract: Recent advances in quantum sensing and computational technologies indicate the possibility of improving the precision of measurements aimed at detecting cosmological particles and weakly interacting massive particles using various qubit platforms. While recent progress has been made, mitigating environmental noise remains a challenge in extracting particle parameters with high fidelity. Addressing these challenges requires efforts on two levels. At the device level, the qubit and its array acting as a probe, must be isolated from electrical and magnetic noise through optimized device geometry. At the signal-processing level, it is necessary to develop filtering methods targeting specific noise spectra based on different qubit architectures. In this work, we explore the possibility of using semiconductor quantum dot spin qubits as a platform to search for quantum chromodynamics axions and, more broadly, axion like particles (ALPs). Starting by deriving an effective Hamiltonian for electron-axion interactions, we identify an axion-induced effective magnetic field and determine the characteristic axion oscillation frequency. To suppress charge noise in the devices and environmental noise, we first analyze the charge noise spectrum and then develop a dedicated filtering and noise-reduction protocol, paving the way for exploring feasible axion mass ranges. Our preliminary study holds promise for enhancing the screening of various axion signals using quantum technologies. We expect that our analysis and filtering protocol can help advance the use of semiconductor quantum dot spin qubit arrays in axion detection. + oai:arXiv.org:2509.06791v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + hep-ex + hep-th + Wed, 10 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/kbty-mxxb - Phys. Rev. A 112, 013319(2025) - Jia-Chen Tang, Xu-Yang Hou, Yan He, Hao Guo + http://creativecommons.org/licenses/by/4.0/ + 10.1109/TQE.2025.3599670 + IEEE Transactions on Quantum Engineering, vol. 6, pp. 1-11, 2025, Art no. 3500311 + Xiangjun Tan, Zhanning Wang - Microwave-field quantum metrology with inherent robustness against detection losses enabled by Rydberg interactions - https://arxiv.org/abs/2505.01506 - arXiv:2505.01506v2 Announce Type: replace -Abstract: Quantum sensing and metrology present one of the most promising near-term applications in the field of quantum technologies, with quantum sensors enabling unprecedented precision in measurements of electric, magnetic or gravitational fields and displacements. Experimental loss at the detection stage remains one of the key obstacles to achieving a truly quantum advantage in many practical scenarios. Here, we combine the capabilities of Rydberg atoms to both sense external fields and be used for quantum information processing, thereby largely overcoming the issue of detection losses. While utilising the large dipole moments of Rydberg atoms in an ensemble to achieve a $\SI{39}{\nV\per\cm \hertz\tothe{-1/2}}$ sensitivity, we employ inter-atomic dipolar interactions to take advantage of an error-prevention protocol that protects information against conventional losses at the detection stage. Counterintuitively, the protocol's idea is based on introducing an additional non-linear, lossy quantum channel, which results in a 3.3-fold enhancement of Fisher information. The presented results pave the way for broader adoption of quantum-information-inspired enhancements enabled by intrinsic interactions present in a sensor system, and more broadly in practical quantum metrology and communication, without the need for a general-purpose quantum computer. - oai:arXiv.org:2505.01506v2 + Quantization of the electromagnetic fields from single atomic or molecular radiators + https://arxiv.org/abs/2509.07359 + arXiv:2509.07359v3 Announce Type: replace +Abstract: A framework is introduced for expressing electromagnetic (EM) potentials and fields of single atomic or molecular emitters modeled as oscillating dipoles, which follows a recently proposed method for solving inhomogeneous wave equations for arbitrary, time-dependent distributions of charge. This framework is first used to evaluate the physical implications of simplifying assumptions made in the standard approach to quantization of the EM fields and the impact of such assumptions on the results of energy and momentum quantization. Then, the exact expressions for the EM potentials and fields, in relation to the oscillating (transition) dipoles properties, afforded by the present framework are used to quantize electromagnetic fields from single emitters and restore the agreement with the well-known classical dipole radiation pattern, while maintaining the quantum mechanical description of electromagnetic radiation in terms of the probability distribution of quantum modes. Contributions of the present analysis to the understanding of photon emission from excited atoms or molecules stimulated by light or vacuum field fluctuations are highlighted, and possible experimental tests and practical applications are proposed. + oai:arXiv.org:2509.07359v3 quant-ph - physics.atom-ph + physics.class-ph physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Stanis{\l}aw Kurzyna, Bartosz Niewelt, Mateusz Mazelanik, Wojciech Wasilewski, Rafa{\l} Demkowicz-Dobrza\'nski, Micha{\l} Parniak + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Valerica Raicu - Quantum Feature Space of a Qubit Coupled to an Arbitrary Bath - https://arxiv.org/abs/2505.03397 - arXiv:2505.03397v4 Announce Type: replace -Abstract: Qubit control protocols have traditionally leveraged a characterisation of the qubit-bath coupling via its power spectral density. Previous work proposed the inference of noise operators that characterise the influence of a classical bath using a grey-box approach that combines deep neural networks with physics-encoded layers. This overall structure is complex and poses challenges in scaling and real-time operations. Here, we show that no expensive neural networks are needed and that this noise operator description admits an efficient parameterisation. We refer to the resulting parameter space as the \textit{quantum feature space} of the qubit dynamics resulting from the coupled bath. We show that the Euclidean distance defined over the quantum feature space provides an effective method for classifying noise processes in the presence of a given set of controls. Using the quantum feature space as the input space for a simple machine learning algorithm (random forest, in this case), we demonstrate that it can effectively classify the stationarity and the broad class of noise processes perturbing a qubit. Finally, we explore how control pulse parameters map to the quantum feature space. - oai:arXiv.org:2505.03397v4 + Locally Purified Maximally Mixed States At Scale: Entanglement Pruning and Symmetries + https://arxiv.org/abs/2509.16439 + arXiv:2509.16439v2 Announce Type: replace +Abstract: Locally Purified Density Operators (LPDOs) are state-of-the-art tensor network ansatze candidates that efficiently represent mixed quantum states at scale. However, given their non-uniqueness, their representational complexity is generally sub-optimal in practical computations. In this work we perform a comprehensive numerical and analytical analysis and resolve this issue in the experimentally relevant limit where noise depolarizes the density operator into a maximally mixed state. To resolve the sub-optimality issue, we analyze two numerical tools, one analytic method, and detail the relations between them. The numerical tools used are fidelity-preserving truncations and isometric gauge transformations leveraging Riemannian optimizations over entropic objective functions. In addition, by invoking the injectivity and symmetry constraints of the maximally mixed LPDO, we also present analytical closed-form expressions for the disentangler and discuss their relation to numerical optimizers. Our work shows how, by minimizing the resources required to represent key states of practical interest in experiment, the efficiency of tensor network algorithms can be substantially increased. This paves the path for uncovering tensor network's fundamental scalability limits and latent potential in representing the wide locus of mixed quantum states that are accessible on near-term quantum devices. + oai:arXiv.org:2509.16439v2 quant-ph - cs.LG - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Chris Wise, Akram Youssry, Alberto Peruzzo, Jo Plested, Matt Woolley + Amit Jamadagni, Eugene Dumitrescu - Quantum RNNs and LSTMs Through Entangling and Disentangling Power of Unitary Transformations - https://arxiv.org/abs/2505.06774 - arXiv:2505.06774v2 Announce Type: replace -Abstract: In this paper, we present a framework for modeling quantum recurrent neural networks (RNNs) and their enhanced version, long short-term memory (LSTM) networks using the core ideas presented by Linden et al. (2009), where the entangling and disentangling power of unitary transformations is investigated. In particular, we interpret entangling and disentangling power as information retention and forgetting mechanisms in LSTMs. Thus, entanglement emerges as a key component of the optimization (training) process. We believe that, by leveraging prior knowledge of the entangling power of unitaries, the proposed quantum-classical framework can guide the design of better-parameterized quantum circuits for various real-world applications. - oai:arXiv.org:2505.06774v2 + Fourier Spectrum of Noisy Quantum Algorithms + https://arxiv.org/abs/2510.06385 + arXiv:2510.06385v2 Announce Type: replace +Abstract: Quantum computing promises exponential speedups for certain problems, yet fully universal quantum computers remain out of reach and near-term devices are inherently noisy. Motivated by this, we study noisy quantum algorithms and the landscape between $\mathsf{BQP}$ and $\mathsf{BPP}$. We build on a powerful technique to differentiate quantum and classical algorithms called the level-$\ell$ Fourier growth (the sum of absolute values of Fourier coefficients of sets of size $\ell$) and show that it can also be used to differentiate quantum algorithms based on the types of resources used. We show that noise acting on a quantum algorithm dampens its Fourier growth in ways intricately linked to the type of noise. + Concretely, we study noisy models of quantum computation where highly mixed states are prevalent, namely: $\mathsf{DQC}_k$ algorithms, where $k$ qubits are clean and the rest are maximally mixed, and $\frac{1}{2}\mathsf {BQP}$ algorithms, where the initial state is maximally mixed, but the algorithm is given knowledge of the initial state at the end of the computation. We establish upper bounds on the Fourier growth of $\mathsf{DQC}_k$, $\frac{1}{2}\mathsf{BQP}$ and $\mathsf{BQP}$ algorithms and leverage the differences between these bounds to derive oracle separations between these models. In particular, we show that 2-Forrelation and 3-Forrelation require $N^{\Omega(1)}$ queries in the $\mathsf{DQC}_1$ and $\frac{1}{2}\mathsf{BQP}$ models respectively. Our results are proved using a new matrix decomposition lemma that might be of independent interest. + oai:arXiv.org:2510.06385v2 quant-ph - cs.LG - Tue, 09 Dec 2025 00:00:00 -0500 + cs.CC + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ammar Daskin + Uma Girish - Nullifiers of non-Gaussian cluster states through homodyne measurement - https://arxiv.org/abs/2505.21066 - arXiv:2505.21066v3 Announce Type: replace -Abstract: In continuous variable optical platforms, large-scale Gaussian cluster states have already been demonstrated, but non-Gaussian resources are essential to achieve universality and fault tolerance in measurement-based quantum computation. However, characterizing and certifying non-Gaussian cluster states remains an outstanding challenge. Here, we introduce a general framework for the characterization of non-Gaussian cluster states based on non-Gaussian nullifiers, extending the widely used Gaussian nullifier concept. We show that these nullifiers can be directly evaluated from homodyne measurement data, making them experimentally accessible. As an illustration, we derive and experimentally demonstrate non-Gaussian nullifiers for photon-subtracted squeezed states. Our results provide a practical and operational tool for certifying quantum non-Gaussianity in large-scale optical cluster states. - oai:arXiv.org:2505.21066v3 + Software Framework for Optically Accessible Quantum Memory Using Group-IV Color Centers in Diamond + https://arxiv.org/abs/2510.07045 + arXiv:2510.07045v3 Announce Type: replace +Abstract: In the rapidly evolving field of quantum technology, the precise and detailed description of quantum components is not just a necessity but the foundation for advancing research, development, and applications. Optically accessible quantum memories are key building blocks for devices such as quantum repeaters and two-factor authentication. The memory we describe here is based on a tin-vacancy color center coupled to a highly efficient cavity. It leverages state-dependent reflection from the cavity and implements high-fidelity fractional single qubit gates via a train of optical $\pi/8$ pulses. We also describe its operation under microwave control, further extending our analysis. Our primary contribution in this work is the integration of this device model into a standardized software framework for quantum memory architectures. + oai:arXiv.org:2510.07045v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Vojt\v{e}ch Kala, Casper A. Breum, Mikkel V. Larsen, Ulrik L. Andersen, Jonas S. Neergaard-Nielsen, Radim Filip, Petr Marek - - - Insightful Approach to Quantum Noise Suppression Below the Standard Quantum Limit Using a Single Mirror and Beam Splitter - https://arxiv.org/abs/2506.08521 - arXiv:2506.08521v3 Announce Type: replace -Abstract: When a coherent electromagnetic wave passes through a beam splitter (BS), it is divided equally into two parts. However, the quantum noise associated with the resulting coherent states, despite being reduced in amplitude by half, remains fundamentally constrained by the quantum noise limit, independent of the intensity. By placing a mirror at the unused input port of the BS, a standing wave is formed in the vicinity of the mirror, which influences the vacuum fluctuations of the coherent state at the BS output. Using semi-classical and quantum mechanical approaches, we calculate the vacuum fluctuations induced by the mirror and demonstrate that the vacuum noise originating from the mirror side periodically reaches zero at the BS output. Leveraging this effect, we show that the vacuum fluctuations of the light split by the BS can be readily reduced below the quantum noise limit. Furthermore, through feedback mechanisms, the vacuum fluctuations of the electromagnetic field at the other output port can also be suppressed below the quantum noise limit. These findings provide a pivotal insight into the manipulation of electromagnetic noise, with broad implications for all experiments involving quantum noise control. - oai:arXiv.org:2506.08521v3 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Sun-Hyun Youn + Yannick Strocka, Mohamed Belhassen, Tim Schr\"oder, Gregor Pieplow - Covert Entanglement Generation over Bosonic Channels - https://arxiv.org/abs/2506.09474 - arXiv:2506.09474v3 Announce Type: replace -Abstract: We explore covert entanglement generation over the lossy thermal-noise bosonic channel, which is a quantum-mechanical model of many practical settings, including optical, microwave, and radio-frequency (RF) channels. Covert communication ensures that an adversary is unable to detect the presence of transmissions, which are concealed in channel noise. We show that a square root law (SRL) for covert entanglement generation similar to that for classical communication: $L_{\rm EG}\sqrt{n}$ entangled bits (ebits) can be generated covertly and reliably over $n$ uses of a bosonic channel. We report a single-letter expression for optimal $L_{\rm EG}$ as well as an achievable method. We additionally analyze the performance of covert entanglement generation using single- and dual-rail photonic qubits, which may be more practical for physical implementation. - oai:arXiv.org:2506.09474v3 + Beyond Hoeffding and Chernoff: Trading conclusiveness for advantages in quantum hypothesis testing + https://arxiv.org/abs/2510.07601 + arXiv:2510.07601v2 Announce Type: replace +Abstract: The ultimate limits of quantum state discrimination are often thought to be captured by asymptotic bounds that restrict the achievable error probabilities, notably the quantum Chernoff and Hoeffding bounds. Here we study hypothesis testing protocols that are permitted a probability of producing an inconclusive discrimination outcome, and investigate their performance when this probability is suitably constrained. We show that even by allowing an arbitrarily small probability of inconclusiveness, the limits imposed by the quantum Hoeffding and Chernoff bounds can be significantly exceeded. This completely circumvents the conventional trade-offs between error exponents in hypothesis testing while incurring only a vanishingly small overhead over conventional approaches. Such improvements over standard state discrimination are robust and can be obtained even when an exponentially vanishing probability of inconclusive outcomes is demanded. Relaxing the constraints on the inconclusive probability can enable even larger advantages, but this comes at a price. We show a 'strong converse' property of this setting: targeting error exponents beyond those achievable with vanishing inconclusiveness necessarily forces the probability of inconclusive outcomes to converge to one. By exactly quantifying the rate of this convergence, we give a complete characterisation of the trade-offs between error exponents and rates of conclusive outcome probabilities. Overall, our results provide a comprehensive asymptotic picture of how the allowance for inconclusive measurement outcomes reshapes optimal quantum hypothesis testing. + oai:arXiv.org:2510.07601v2 quant-ph - cs.CR - Tue, 09 Dec 2025 00:00:00 -0500 + cs.IT + math-ph + math.IT + math.MP + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Evan J. D. Anderson, Michael S. Bullock, Ohad Kimelfeld, Christopher K. Eyre, Filip Rozp\k{e}dek, Uzi Pereg, Boulat A. Bash + Kaiyuan Ji, Bartosz Regula - Physical-Layer Machine Learning with Multimode Interferometric Photon Counting - https://arxiv.org/abs/2506.12309 - arXiv:2506.12309v2 Announce Type: replace -Abstract: The learning of the physical world relies on sensing and data post-processing. When the signals are weak, multidimensional and correlated, the performance of learning is often bottlenecked by the quality of sensors, calling for integrating quantum sensing into the learning of such physical-layer data. An example of such a learning scenario is the stochastic quadrature displacements of electromagnetic fields, modeling optomechanical force sensing, radiofrequency photonic sensing, microwave cavity weak signal sensing, and other applications. We propose a unified protocol that combines machine learning with interferometric photon counting to reduce noise and reveal correlations. By applying variational quantum learning with multimode programmable quantum measurements, we enhance signal extraction. Our results show that multimode interferometric photon counting outperforms conventional homodyne detection proposed in prior works for tasks like principal component analysis (PCA) and cross-correlation analysis (CCA), even below vacuum noise levels. To further enhance the performance, we also integrate entanglement-enhanced modules, in the form of squeezed state distribution and anti-squeezing at detection, into the protocol. Combining multimode interferometric photon counting and multipartite entanglement, the proposed protocol provides a powerful toolbox for learning weak signals. - oai:arXiv.org:2506.12309v2 + Purified phase estimation samples spectra efficiently + https://arxiv.org/abs/2510.14744 + arXiv:2510.14744v2 Announce Type: replace +Abstract: Quantum phase estimation (QPE) is a cornerstone algorithm for extracting Hamiltonian eigenvalues, but its standard, eigenstate-centric form relies on carefully prepared coherent inputs that are costly or impractical for many strongly correlated systems. We overcome this bottleneck via DOS-QPE, an incoherent, purification-based variant of QPE that works directly with mixed-state probes and estimates the density of states (DOS) of the Hamiltonian. By adding a purification register and simple entangling layers, we turn standard QPE into an ensemble-based DOS sampler without modifying the core phase-estimation block. Conceptually, this purification closely aligns with the recent random purification channel framework from quantum learning theory, but instantiated here as a concrete phase-estimation circuit. We further equip DOS-QPE with symmetry-adapted input ensembles and a compressed-sensing reconstruction pipeline, and demonstrate on fermionic and nuclear Hamiltonians that a single experimental setup can recover rich spectral information relevant to thermodynamics, spectroscopy, and many-body structure. + oai:arXiv.org:2510.14744v2 quant-ph - physics.optics - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/mft4-mbzc - Phys. Rev. Applied 24, 054050 (2025) - Jia-Jin Feng, Anthony J. Brady, Quntao Zhuang + Stefano Scali, Josh Kirsopp, Antonio M\'arquez Romero, Micha{\l} Krompiec - Loss of integrability in a system with two-photon interactions - https://arxiv.org/abs/2506.16514 - arXiv:2506.16514v2 Announce Type: replace -Abstract: Light-matter systems that exhibit two-photon interactions have emerged as powerful platforms for exploring quantum applications. In this work, we focus on the two-photon Dicke model, a system of significant experimental relevance that displays spectral collapse and undergoes a phase transition from a normal to a superradiant phase. We analyze the normal phase, where a classical limit with two degrees of freedom can be derived using a mean-field approximation. Our study presents a detailed investigation of the loss of integrability in the two-photon Dicke model, employing both quantum and classical diagnostics. These results allow us to explore various dynamical features of the system, including the onset of chaos and the existence of mixed phase-space behavior. - oai:arXiv.org:2506.16514v2 + Measurement-Based Fault-Tolerant Quantum Computation on High-Connectivity Devices: A Resource-Efficient Approach toward Early FTQC + https://arxiv.org/abs/2510.18652 + arXiv:2510.18652v2 Announce Type: replace +Abstract: We propose a measurement-based FTQC (MB-FTQC) architecture for high-connectivity platforms such as trapped ions and neutral atoms. The key idea is to use verified logical ancillas combined with Knill's error-correcting teleportation, eliminating repeated syndrome measurements and simplifying decoding to logical Pauli corrections, thus keeping classical overhead low. To align with near-term device scales, we present two implementations benchmarked under circuit-level depolarizing noise: (i) a Steane-code version that uses analog $R_Z(\theta)$ rotations, akin to the STAR architecture [Akahoshi et al., PRX Quantum 5, 010337], aiming for the megaquop regime ($\sim 10^6$ $T$ gates) on devices with thousands of qubits; and (ii) a Golay-code version with higher-order zero-level magic-state distillation, targeting the gigaquop regime ($\sim 10^9$ $T$ gates) on devices with tens of thousands of qubits. At a physical error rate $p=10^{-4}$, the Steane path supports $5\times 10^{4}$ logical $R_Z(\theta)$ rotations, corresponding to $\sim 2.4\times 10^{6}$ $T$ gates and enabling megaquop-scale computation. With about $2{,}240$ physical qubits, it achieves $\log_{2}\mathrm{QV}=64$. The Golay path supports more than $2\times 10^{9}$ $T$ gates, enabling gigaquop-scale computation. These results suggest that our architecture can deliver practical large-scale quantum computation on near-term high-connectivity hardware without relying on resource-intensive surface codes or complex code concatenation. + oai:arXiv.org:2510.18652v2 quant-ph - cond-mat.stat-mech - nlin.CD - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/c618-hql5 - Phys. Rev. A 112, 063707 (2025) - Fabrizio Ram\'irez, David Villase\~nor, Viani S. Morales-Guzm\'an, Darly Y. Castro, Jorge G. Hirsch + Yohei Ibe, Yutaka Hirano, Yasuo Ozu, Toru Kawakubo, Keisuke Fujii - A dynamic circuit for the honeycomb Floquet code - https://arxiv.org/abs/2507.08069 - arXiv:2507.08069v4 Announce Type: replace -Abstract: In the typical implementation of a quantum error-correcting code, each stabilizer is measured by entangling one or more ancilla qubits with the data qubits and measuring the ancilla qubits to deduce the value of the stabilizer. Recently, the dynamic circuit approach has been introduced, in which stabilizers are measured without ancilla qubits. Here, we demonstrate that dynamic circuits are particularly useful for the Floquet code. Our dynamic circuit increases the timelike distance of the code, automatically removes leakage, and both significantly increases the threshold and lowers the logical error rate compared to the standard ancilla-based circuit. At a physical error rate of $10^{-3}$, we estimate a nearly $3\times$ reduction in the number of qubits required to reach a $10^{-12}$ logical error rate. - oai:arXiv.org:2507.08069v4 + A Non-Variational Quantum Approach to the Job Shop Scheduling Problem + https://arxiv.org/abs/2510.26859 + arXiv:2510.26859v2 Announce Type: replace +Abstract: Quantum heuristics offer a potential advantage for combinatorial optimization but are constrained by near-term hardware limitations. We introduce Iterative-QAOA, a variant of QAOA designed to mitigate these constraints. The algorithm combines a non-variational, shallow-depth circuit approach using fixed-parameter schedules with an iterative warm-starting process. We benchmark the algorithm on Just-in-Time Job Shop Scheduling Problem (JIT-JSSP) instances on IonQ Forte Generation QPUs, representing some of the largest such problems ever executed on quantum hardware. We compare the performance of the algorithm against both the Variational Quantum Imaginary Time Evolution (VarQITE) algorithm and the non-variational Linear Ramp (LR) QAOA algorithm. We find that Iterative-QAOA robustly converges to find optimal solutions as well as high-quality, near-optimal solutions for all problem instances evaluated. We evaluate the algorithm on larger problem instances up to 97 qubits using tensor network simulations. The scaling behavior of the algorithm indicates potential for solving industrial-scale problems on fault-tolerant quantum computers. + oai:arXiv.org:2510.26859v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + cs.ET + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/qklt-4jnj - Phys. Rev. A 112, 062406 (2025) - Jahan Claes + Miguel Angel Lopez-Ruiz, Emily L. Tucker, Emma M. Arnold, Evgeny Epifanovsky, Ananth Kaushik, Martin Roetteler - Continuous-time parametrization of neural quantum states for quantum dynamics - https://arxiv.org/abs/2507.08418 - arXiv:2507.08418v3 Announce Type: replace -Abstract: Neural quantum states are a promising framework for simulating many-body quantum dynamics, as they can represent states with volume-law entanglement. As time evolves, the neural network parameters are typically optimized at discrete time steps to approximate the wave function at each point in time. Given the differentiability of the wave function stemming from the Schr\"odinger equation, here we impose a time-continuous and differentiable parameterization of the neural network by expressing its parameters as linear combinations of temporal basis functions with trainable, time-independent coefficients. We test this ansatz, referred to as the smooth neural quantum state (\textit{s}-NQS) with a loss function defined over an extended time interval, under a sudden quench of a non-integrable many-body quantum spin chain. We demonstrate accurate time evolution using a restricted Boltzmann machine as the instantaneous neural network architecture. We show that the parameterization enables accurate simulations with fewer variational parameters, independent of time-step resolution. Furthermore, the smooth neural quantum state also allows us to initialize and evaluate the wave function at times not included in the training set, both within and beyond the training interval. - oai:arXiv.org:2507.08418v3 + Optimal transfer of entanglement in oscillator chains in non-Markovian open systems + https://arxiv.org/abs/2511.00323 + arXiv:2511.00323v2 Announce Type: replace +Abstract: We considered the transfer of continuous-variable entangled states in coupled oscillator chains embedded in a generic environment. We demonstrate high-fidelity transfer via optimal control in two configurations - a linear chain and an X-shaped chain. More specifically, we use the Krotov optimization algorithm to design control fields that achieve the desired state transfer. Under the environmental memory effects, the Krotov algorithm needs to be modified, since the dissipative terms in non-Markovian dynamics are generally governed by the time-dependent system Hamiltonian. Remarkably, we can achieve high-fidelity transfer by simply tuning the frequencies of the oscillators while keeping the coupling strength constant, even in the presence of open-system effects. For the system under consideration, we find that quantum memory effects can aid in the transfer of entanglement and show improvement over the memoryless case. In addition, it is possible to target a range of entangled states, making it unnecessary to know the parameters of the initial state beforehand. + oai:arXiv.org:2511.00323v2 quant-ph - cond-mat.str-el - physics.comp-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Dingzu Wang, Wenxuan Zhang, Xiansong Xu, Dario Poletti + 10.3390/e27121239 + Entropy 2025, 27(12), 1239 + Da-Wei Luo, Edward Yu, Ting Yu - Approximate combinatorial optimization with Rydberg atoms: the barrier of interpretability - https://arxiv.org/abs/2507.22761 - arXiv:2507.22761v2 Announce Type: replace -Abstract: Analog quantum computing with Rydberg atoms is seen as an avenue to solve hard graph optimization problems, because they naturally encode the Maximum Independent Set (MIS) problem on Unit-Disk (UD) graphs, a problem that admits rather efficient approximation schemes on classical computers. Going beyond UD-MIS to address generic graphs requires embedding schemes, typically with chains of ancilla atoms, and an interpretation algorithm to map results back to the original problem. However, interpreting approximate solutions obtained with realistic quantum computers proves to be a difficult problem. As a case study, we evaluate the ability of two interpretation strategies to correct errors in the recently introduced Crossing Lattice embedding. We find that one strategy, based on finding the closest embedding solution, leads to very high qualities, albeit at an exponential cost. The second strategy, based on ignoring defective regions of the embedding graph, is polynomial in the graph size, but it leads to a degradation of the solution quality which is prohibitive under realistic assumptions on the defect generation. Moreover, more favorable defect scalings lead to a contradiction with well-known approximability conjectures. Therefore, it is unlikely that a scalable and generic improvement in solution quality can be achieved with Rydberg platforms -- thus moving the focus to heuristic algorithms. - oai:arXiv.org:2507.22761v2 + Annual-modulation fingerprint of the axion wind induced sideband triplet in quantum dot spin qubit sensors + https://arxiv.org/abs/2511.03630 + arXiv:2511.03630v2 Announce Type: replace +Abstract: We propose a phase-coherent, narrowband magnetometer for searching couplings between axions or axion-like particles (ALPs) and electron spins, using gate-defined silicon quantum-dot spin qubits. With repeated Ramsey echo sequences and dispersive readout, the qubit precession response can be tracked with sub-Hz spectral resolution. The accessible axion mass window is determined using a series of filtering protocols that take into account sensing noise, including readout errors and $1/f$ noise. We demonstrate clear evidence of sidereal modulation of the signal due to Earth's rotation, while Earth's orbital motion produces an annual amplitude envelope that generates sidebands at fixed frequency spacing $\pm \Omega_\oplus$ around the sidereal component. For axion masses between $1$-$10~\mu{\rm eV}$, the proposed method covers axion-electron coupling strengths $g_{ae}$ ranging from $10^{-14}$ to $10^{-10}$. Including both daily and annual modulation patterns in the likelihood analysis enhances the rejection of stationary or instrumental noise. Our results indicate that spin-qubit magnetometry can achieve sensitivities approaching those suggested by astrophysical considerations, providing a complementary, laboratory-based probe of axion-electron interactions. Although we focus on silicon spin-qubit architectures, the approach is broadly applicable to spin-based quantum sensors. + oai:arXiv.org:2511.03630v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + hep-ph + Wed, 10 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1103/ss3t-j4y5 - Phys. Rev. A 112, 042441 (2025) - Christian de Correc, Thomas Ayral, Corentin Bertrand - - - Extended parameter shift rules with minimal derivative variance for parameterized quantum circuits - https://arxiv.org/abs/2508.08802 - arXiv:2508.08802v2 Announce Type: replace -Abstract: Parameter shift rules (PSRs) are useful methods for computing arbitrary-order derivatives of the cost function in parameterized quantum circuits. The basic idea of PSRs is to evaluate the cost function at different parameter shifts, then use specific coefficients to combine them linearly to obtain the exact derivatives. In this work, we propose an extended parameter shift rule (EPSR) which generalizes a broad range of existing PSRs and has the following two advantages. First, EPSR offers an infinite number of possible parameter shifts, allowing the selection of the optimal parameter shifts to minimize the final derivative variance and thereby obtaining the more accurate derivative estimates with limited quantum resources. Second, EPSR extends the scope of the PSRs in the sense that EPSR can handle arbitrary Hermitian operator $H$ in gate $U(x) = \exp (iHx)$ in the parameterized quantum circuits, while existing PSRs are valid only for simple Hermitian generators $H$ such as simple Pauli words. Additionally, we show that the widely used ``general PSR'', introduced by Wierichs et al. (2022), is a special case of our EPSR, and we prove that it yields globally optimal shifts for minimizing the derivative variance under the weighted-shot scheme. Finally, through numerical simulations, we demonstrate the effectiveness of EPSR and show that the usage of the optimal parameter shifts indeed leads to more accurate derivative estimates. - oai:arXiv.org:2508.08802v2 - quant-ph - math.OC - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/f57b-q28w - Zhijian Lai, Jiang Hu, Dong An, Zaiwen Wen - - - Quantum Seniority-based Subspace Expansion: Linear Combinations of Short-Circuit Unitary Transformations for the Electronic Structure Problem - https://arxiv.org/abs/2509.01061 - arXiv:2509.01061v2 Announce Type: replace -Abstract: Quantum SENiority-based Subspace Expansion (Q-SENSE) is a hybrid quantum-classical algorithm that interpolates between the Variational Quantum Eigensolver (VQE) and Configuration Interaction (CI) methods. It constructs Hamiltonian matrix elements on a quantum device and solves the resulting eigenvalue problem classically. Unlike other expansion-based methods -- such as Quantum Subspace Expansion (QSE), Quantum Krylov Algorithms, and the Non-Orthogonal Quantum Eigensolver -- Q-SENSE introduces seniority operators as artificial symmetries to construct orthogonal basis states. This seniority-symmetry-based approach reduces one of the primary limitations of VQE on near-term quantum hardware -- circuit depth -- at the cost of measuring additional matrix elements. The artificial symmetries also reduce the number of Hamiltonian terms that must be measured, as only a small fraction of the terms couple basis states in different seniority subspaces. With all these merits, Q-SENSE offers a scalable and resource-efficient route to quantum advantage on near-term quantum devices and in the early fault-tolerant regime. - oai:arXiv.org:2509.01061v2 - quant-ph - physics.chem-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Smik Patel, Praveen Jayakumar, Rick Huang, Tao Zeng, Artur F. Izmaylov - - - A method for the numerical analysis of hybrid lumped-distributed superconducting quantum circuits - https://arxiv.org/abs/2509.03651 - arXiv:2509.03651v2 Announce Type: replace -Abstract: We present a method for the numerical analysis of superconducting quantum circuits combining lumped elements, either linear or non-linear (i.e.~Josephson junctions), and distributed coplanar waveguide (CPW) structures. CPW transmission lines and multiline couplers are directly modeled without discretizing them into lumped-element equivalents, and the circuit Hamiltonian parameters are extracted by using the energy participation ratio (EPR) method. This approach enables fast and accurate extraction of mode frequencies, anharmonicities, cross-Kerr interactions, and Purcell decay rates without relying on full electromagnetic simulations, while naturally accounting for higher-order modes of distributed components. - We have implemented the proposed method in a Python framework, QuLTRA (Quantum hybrid Lumped and TRansmission lines circuits Analyzer), which we have used to validate the approach against full electromagnetic simulations (Ansys HFSS, pyEPR), existing circuit-analysis tools (QuCAT), and designs reported in the literature. The comparisons show excellent agreement with orders-of-magnitude reductions in computational time relative to full-wave solvers. We demonstrate applications including Purcell-protected readout, multimode ultra-strong coupling, and multiplexed qubit readout, illustrating how the method can support fast and reliable early-stage circuit design. - oai:arXiv.org:2509.03651v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Simona Zaccaria, Antonio Gnudi - - - Geometric Discord of any arbitrary dimensional bipartite system and its application in quantum key distribution - https://arxiv.org/abs/2509.04927 - arXiv:2509.04927v4 Announce Type: replace -Abstract: Entangled quantum states are regarded as a key resource in quantum key distribution (QKD) protocols. However, quantum correlations, other than entanglement can also play a significant role in the QKD protocols. In this work, we will focus on one such measure of quantum correlation, known as geometric quantum discord (GQD). Firstly, we derive an analytical expression of GQD for two-qutrit quantum systems and further generalize it for $d_1\otimes d_2$ dimensional systems. Next, we apply the concept of GQD in studying QKD. In particular, if the shared resource state is an entangled state constructed with the linear combination of the tensor product of the Bell pair and the state $\sigma_i$'s, $i=0,1,2,3$, then we have shown that under some assumption on $\sigma_i$'s, the lower bound for a distillable secret key rate $K_D$ can be expressed in terms of GQD of $\frac{\sigma_0+\sigma_1}{2}$ and $\frac{\sigma_2+\sigma_3}{2}$. Thus, the distillable key rate depends upon the GQD of $\frac{\sigma_0+\sigma_1}{2}$ and $\frac{\sigma_2+\sigma_3}{2}$, when the communicating parties uses private states for generating a secret key in presence of an eavesdropper. Further, for a certain range of GQD of $\frac{\sigma_0+\sigma_1}{2}$ and $\frac{\sigma_2+\sigma_3}{2}$, we find that there exists some NPT entangled resource state for which the successful generation of the secret key may not be guaranteed. We, moreover study the behavior of distillable key rate when the geometric discord of $\frac{\sigma_0+\sigma_1}{2}$ and $\frac{\sigma_2+\sigma_3}{2}$ increases, decreases or remains constant, with the help of a few examples. - oai:arXiv.org:2509.04927v4 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1088/1402-4896/ae1f4d - Physica Scripta, 100, 125102 (2025) - Rashi Jain, Satyabrata Adhikari + Xiangjun Tan, Zhanning Wang - A Modular, Adaptive, and Scalable Quantum Factoring Algorithm - https://arxiv.org/abs/2509.05010 - arXiv:2509.05010v5 Announce Type: replace -Abstract: Shor's algorithm for integer factorization offers an exponential speedup over classical methods but remains impractical on Noisy Intermediate Scale Quantum (NISQ) hardware due to the need for many coherent qubits and very deep circuits. Building on our recent work on adaptive and windowed phase-estimation methods, we have developed a modular, windowed formulation of Shor's algorithm that mitigates these limitations by restructuring phase estimation into shallow, independent circuit blocks that can be executed sequentially or in parallel, followed by lightweight classical postprocessing. This approach allows for a reduction in the size of the phase (or counting) register from a large number of qubits down to a small, fixed block size of only a few qubits (for example, three or four phase qubits were sufficient for the computational examples considered in this work), while leaving the work register requirement unchanged. The independence of the blocks allows for parallel execution and makes the approach more compatible with near-term hardware than the standard Shor's formulation. An additional feature of the framework is the overlap mechanism, which introduces redundancy between blocks and enables robust reconstruction of phase information, though zero-overlap configurations can also succeed in certain regimes. Numerical simulations verify the correctness of the modular formulation while also showing substantial reductions in counting qubits per block. - oai:arXiv.org:2509.05010v5 + Family of two-parameter multipartite entanglement measures + https://arxiv.org/abs/2511.09415 + arXiv:2511.09415v2 Announce Type: replace +Abstract: Multipartite entanglement is regarded as a crucial physical resource in quantum network communication. However, due to the intrinsic complexity of quantum many-body systems, identifying a multipartite entanglement measure that is both efficiently computable and capable of accurately characterizing entanglement remains a challenging problem. To address these issues, we propose a family of two-parameter multipartite entanglement measures for mixed states, termed unified-entropy concentratable entanglements. Many well-known multipartite entanglement measures are recovered as special cases of this family of measures, such as the entanglement of formation and the concentratable entanglements introduced in [Phys. Rev. Lett. 127, 140501 (2021)]. We demonstrate that the unified-entropy concentratable entanglements constitutes a well-defined entanglement monotones, and establish several desirable properties it satisfies, such as subadditivity and continuity. We further investigate the ordering relations of unified-entropy concentratable entanglements and discuss how these quantities can be efficiently estimated on near-term quantum devices. As an application, we demonstrate that the unified-entropy concentratable entanglements can effectively distinguish between multi-qubit Greenberger-Horne-Zeilinger (GHZ) states and W states. The ordering relations of these entanglement measures are further validated using four-partite star quantum network states and four-qubit Dicke states. Moreover, we find that the unified-entropy concentratable entanglements exhibit greater sensitivity than the original concentratable entanglements in detecting certain four-partite star quantum network states. + oai:arXiv.org:2511.09415v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alok Shukla, Prakash Vedula + 10.1103/7gg9-klc4 + Physical Review A 112,062418 (2025) + Yu Luo, Zhihua Guo, Fanxu Meng, Chen-Ming Bai - Tunneling of bosonic qubits under local dephasing through microscopic approach - https://arxiv.org/abs/2509.05704 - arXiv:2509.05704v2 Announce Type: replace -Abstract: We present a microscopic derivation of a master equation for two-component bosons (bosonic qubits) which tunnel between spatially separated modes under local dephasing noise. Starting from the full system-bath Hamiltonian with Lorentzian coupling distributions, we analytically obtain a time-local master equation whose structure reveals intrinsic non-Markovian features and recovers the standard phenomenological dephasing model in the short-time limit. Comparison with exact pseudomode simulations confirms its validity beyond weak-coupling and Markovian regimes. We identify a resonance condition between tunneling and bath frequencies for which dephasing drives the system towards correlated steady states, stabilizing coherence and entanglement instead of suppressing them. These results establish a rigorous microscopic foundation for dephasing models in bosonic tunneling systems and reveal a noise-induced mechanism for steady-state entanglement. - oai:arXiv.org:2509.05704v2 + Weight-based measure of quantum memory as a universal and operational benchmark + https://arxiv.org/abs/2511.09417 + arXiv:2511.09417v2 Announce Type: replace +Abstract: Quantum memory plays a critical role in quantum communication, sensing, and computation. However, studies on quantum memory under a unified benchmarking framework remain scarce. In this paper, we propose a weight-based quantifier as a benchmarking method to evaluate the performance advantage of quantum memory in nonlocal exclusion tasks. We establish a general lower bound for the weight-based measure of quantum memory. Moreover, this measure provides fundamental theoretical bounds for transforming a general channel into an ideal quantum memory. Finally, we present explicit calculations of the weight-based quantifier for various channels, including unitary channels, depolarizing channels, maximal replacement channels, stochastic damping channels, and erasure channels. + oai:arXiv.org:2511.09417v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alberto Ferrara, Farzam Nosrati, Andrea Smirne, Jyrki Piilo, Rosario Lo Franco - - - Loss-tolerant parallelized Bell-state generation with a hybrid cat qudit - https://arxiv.org/abs/2509.08577 - arXiv:2509.08577v2 Announce Type: replace -Abstract: Having multiple Bell pairs shared by distant quantum registers provides a key resource for both quantum networks and distributed quantum computing. In this paper, we present a protocol for parallelized Bell-pair generation that uses the phase of a coherent light pulse to encode a qudit, enabling the simultaneous generation of multiple Bell pairs. By encoding a qudit in a basis of light-matter Schr\"odinger's cat states, the loss of a photon in transit can be detected through an $XX$ parity syndrome, allowing the backaction due to the lost photon to be deterministically corrected through single-qubit rotations. The protocol presented here is compatible with existing technologies in both optical and microwave (circuit QED) architectures, supporting near-term implementation across diverse quantum platforms. - oai:arXiv.org:2509.08577v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Phys. Rev. A 112, 062609 (2025) - Z. M. McIntyre, W. A. Coish + 10.1103/9fj9-x3v6 + Physical Review A 112,062408 (2025) + Jinghang Zhang, Yu Luo - Speeding up Pontus-Mpemba effects via dynamical phase transitions - https://arxiv.org/abs/2509.09366 - arXiv:2509.09366v2 Announce Type: replace -Abstract: We demonstrate that open quantum systems exhibiting dynamical phase transitions (DPTs) allow for efficient protocols implementing the Pontus-Mpemba effect. The relaxation speed-up toward a predesignated target state is tied to the existence of a long metastable time window preceding the DPT and can be exploited in applications to systematically optimize quantum protocols. As paradigmatic example for the connection between DPTs and quantum Mpemba effects, we study one-dimensional (1D) interacting lattice fermions corresponding to a dissipative variant of the Gross-Neveu (GN) model. - oai:arXiv.org:2509.09366v2 + Self-interacting quantum particles and the Dirac delta potential + https://arxiv.org/abs/2511.14424 + arXiv:2511.14424v2 Announce Type: replace +Abstract: The Dirac delta function potential is considered within the real Hilbert space approach for complex wave functions, as well as quaternionic wave functions. As has been previously determined, the real Hilbert space approach enables the possibility of self-interacting physical systems. The self-interaction precludes confining states, and also imposes non-stationary quantum states, both of them representing novel situations that cannot be observed in terms of quantum wave functions. These results remark the differences between quaternionic quantum mechanics ($\mathbbm H$QM) and complex quantum mechanics ($\mathbbm C$QM), and also establish a method of solving the wave equation that may be applied to a variety of different cases. + oai:arXiv.org:2511.14424v2 quant-ph - cond-mat.stat-mech - cond-mat.str-el - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Andrea Nava, Reinhold Egger, Bidyut Dey, Domenico Giuliano + Sergio Giardino - Driving the Unruh Response - https://arxiv.org/abs/2509.16710 - arXiv:2509.16710v2 Announce Type: replace -Abstract: The Unruh effect, central to quantum field theory in curved spacetime, states that uniformly accelerated observers perceive the Minkowski vacuum as a thermal ensemble of Rindler excitations. Building on this foundation and drawing analogies from squeezing in quantum optics, we investigate how entangled, non-thermal excitations generated by bilocal driving sources contribute to the accelerated response. These paired excitations act as inertial microstates within the thermal Unruh ensemble, suggesting that portions of the effect can be interpreted as source-driven. To capture this, we employ modular automorphisms from algebraic QFT to track localization of modes and observers across nested Rindler wedges. We then construct compact wave-packet approximations using parabolic cylinder functions, providing a smooth interpolation between wedge-supported thermal modes and fully localized non-thermal excitations. This approach situates the Unruh response within a broader framework where standard thermality emerges alongside, and sometimes from, localized source-induced structure. - oai:arXiv.org:2509.16710v2 + Kernelized Decoded Quantum Interferometry + https://arxiv.org/abs/2511.20016 + arXiv:2511.20016v3 Announce Type: replace +Abstract: Decoded Quantum Interferometry (DQI) promises superpolynomial speedups for structured optimization; however, its practical realization is often hindered by significant sensitivity to hardware noise and spectral dispersion. To bridge this gap, we introduce Kernelized Decoded Quantum Interferometry (k-DQI), a unified framework that integrates spectral engineering directly into the quantum circuit architecture. By inserting a unitary kernel prior to the interference step, k-DQI actively reshapes the problem's energy landscape, concentrating the solution mass into a ``decoder-friendly'' low-frequency head. We formalize this advantage through a novel robustness metric, the noise-weighted head mass $\Sigma_K$, and prove a Monotonic Improvement Theorem, which establishes that maximizing $\Sigma_K$ guarantees higher decoding success rates under local depolarizing noise. We substantiate these theoretical gains in Optimal Polynomial Interpolation (OPI) and LDPC-like problems, demonstrating that kernel tuning functions as a ``spectral lens'' to recover signal otherwise lost to isotropic noise. Crucially, we provide explicit, efficient circuit realizations using Chirp and Linear Canonical Transform (LCT) kernels that achieve significant boosts in effective signal-to-noise ratio with negligible depth overhead ($\tilde{O}(n)$ to $\tilde{O}(n^2)$). Collectively, these results reframe DQI from a static algorithm into a tunable, noise-aware protocol suited for near-term error-corrected environments. + oai:arXiv.org:2511.20016v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Kevin Player - - - On the Feasibility of Exact Unitary Transformations for Many-body Hamiltonians - https://arxiv.org/abs/2510.10957 - arXiv:2510.10957v2 Announce Type: replace -Abstract: Exact unitary transformations play a central role in the analysis and simulation of many-body quantum systems, yet the conditions under which they can be carried out exactly and efficiently remain incompletely understood. We show that exact transformations arise whenever the adjoint action of a unitary's generator defines a linear map within a finite-dimensional operator space. In this regime, there exists a finite-degree polynomial that annihilates the adjoint map, rendering the Baker-Campbell-Hausdorff (BCH) expansion finite. We identify the role of Lie algebras and their modules in producing finite BCH expansions in all known cases. This perspective brings together previously disparate examples of exact transformations under a single unifying principle and clarifies how algebraic relations between generators and transformed operators determine the polynomial degree of the transformation. We illustrate this framework for previously known cases of efficient unitary transformations including unitary coupled-cluster and Pauli product generators. Using this framework, we propose a new class of fermionic generators that can be used for efficient transformations. The result establishes sufficient algebraic conditions for when exact unitary transformations are possible and provides new strategies for reducing their computational cost in quantum simulation and constructing feasible unitary transformations. - oai:arXiv.org:2510.10957v2 - quant-ph - physics.chem-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Praveen Jayakumar, Tao Zeng, Artur F. Izmaylov - - - HPC-Driven Modeling with ML-Based Surrogates for Magnon-Photon Dynamics in Hybrid Quantum Systems - https://arxiv.org/abs/2510.22221 - arXiv:2510.22221v2 Announce Type: replace -Abstract: Simulating hybrid magnonic quantum systems remains a challenge due to the large disparity between the timescales of the two systems. We present a massively parallel GPU-based simulation framework that enables fully coupled, large-scale modeling of on-chip magnon-photon circuits. Our approach resolves the dynamic interaction between ferromagnetic and electromagnetic fields with high spatiotemporal fidelity. To accelerate design workflows, we develop a physics-informed machine learning surrogate trained on the simulation data, reducing computational cost while maintaining accuracy. This combined approach reveals real-time energy exchange dynamics and reproduces key phenomena such as anti-crossing behavior and the suppression of ferromagnetic resonance under strong electromagnetic fields. By addressing the multiscale and multiphysics challenges in magnon-photon modeling, our framework enables scalable simulation and rapid prototyping of next-generation quantum and spintronic devices. - oai:arXiv.org:2510.22221v2 - quant-ph - cs.LG - physics.comp-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jialin Song, Yingheng Tang, Pu Ren, Shintaro Takayoshi, Saurabh Sawant, Yujie Zhu, Jia-Mian Hu, Andy Nonaka, Michael W. Mahoney, Benjamin Erichson, Zhi Yao + Fumin Wang - Anti-concentration is (almost) all you need - https://arxiv.org/abs/2510.23719 - arXiv:2510.23719v2 Announce Type: replace -Abstract: Until very recently, it was generally believed that the (approximate) 2-design property is strictly stronger than anti-concentration of random quantum circuits, mainly because it was shown that the latter anti-concentrate in logarithmic depth, while the former generally need linear depth circuits. This belief was disproven by recent results which show that so-called relative-error approximate unitary designs can in fact be generated in logarithmic depth, implying anti-concentration. Their result does however not apply to ordinary local random circuits, a gap which we close in this paper, at least for 2-designs. More precisely, we show that anti-concentration of local random quantum circuits already implies that they form relative-error approximate state 2-designs, making them equivalent properties for these ensembles. Our result holds more generally for any random circuit which is invariant under local (single-qubit) unitaries, independent of the architecture. - oai:arXiv.org:2510.23719v2 + Qubit Reuse Beyond Reorder and Reset: Optimizing Quantum Circuits by Fully Utilizing the Potential of Dynamic Circuits + https://arxiv.org/abs/2511.22712 + arXiv:2511.22712v2 Announce Type: replace +Abstract: Qubit reuse offers a promising way to reduce the hardware demands of quantum circuits, but current approaches are largely restricted to reordering measurements and applying qubit resets. In this work, we present an approach to further optimize quantum circuits by fully utilizing the potential of dynamic quantum circuits-more precisely by moving measurements and introducing dynamic circuit primitives such as classically controlled gates in a way that forges entirely new pathways for qubit reuse. This significantly reduces the number of required qubits for a variety of circuits, creating new opportunities for running complex circuits on near-term devices with limited qubit counts. We show that the proposed approach drastically outperforms existing methods, reducing qubit requirements where previous approaches are unable to do so for popular quantum circuits such as Quantum Phase Estimation (QPE), Quantum Fourier Transform~(QFT), and Variational Quantum Eigensolver (VQE) ans\"atze, as well as leading to improvements of up to 95% for sparse random circuits. + oai:arXiv.org:2511.22712v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Markus Heinrich, Jonas Haferkamp, Ingo Roth, Jonas Helsen + Damian Rovara, Lukas Burgholzer, Robert Wille - Mixed-State Measurement-Induced Phase Transitions in Imaginary-Time Dynamics - https://arxiv.org/abs/2511.04402 - arXiv:2511.04402v2 Announce Type: replace -Abstract: Mixed-state phase transitions have recently attracted growing attention as a new frontier in nonequilibrium quantum matter and quantum information. In this work, we introduce the measurement-dressed imaginary-time evolution (MDITE) as a novel framework to explore mixed-state quantum phases and decoherence-driven criticality. In this setup, alternating imaginary-time evolution and projective measurements generate a competition between coherence-restoring dynamics and decoherence-inducing events. While reminiscent of monitored unitary circuits, MDITE fundamentally differs in that the physics is encoded in decoherent mixed states rather than in quantum trajectories. We demonstrate that this interplay gives rise to a novel class of mixed-state phase transitions, using numerical simulations of the one-dimensional transverse-field Ising model and the two-dimensional columnar dimerized Heisenberg model. Notably, the observed transitions do not fall into any previously established universality classes. Furthermore, we provide a diagrammatic representation of the evolving state, which naturally enables efficient studies of MDITE with quantum Monte Carlo and other many-body numerical methods, thereby extending investigations of mixed-state phase transitions to large-scale and higher-dimensional systems. In addition, the representation provides a natural interpretation of the phase transitions in terms of cluster formation within the simulations. Our results highlight MDITE as a powerful paradigm for investigating non-unitary dynamics and the fundamental role of decoherence in many-body quantum systems. - oai:arXiv.org:2511.04402v2 + Quench dynamics of the quantum XXZ chain with staggered interactions: Exact results and simulations on digital quantum computers + https://arxiv.org/abs/2512.03341 + arXiv:2512.03341v2 Announce Type: replace +Abstract: We investigate quench dynamics in the quantum $S=1/2$ XXZ antiferromagnetic chain with staggered and anisotropic interactions in the flat-band limit. Our quench protocol interchanges the odd- and even-bond strengths of a fully dimerized chain, enabling us to derive exact time-dependent states for arbitrary even system sizes by working in the Bell basis. We obtain closed-form, size-independent expressions for the von Neumann and second-order R\'enyi entanglement entropies. We further calculate exact Loschmidt echoes and the corresponding return rate functions across various anisotropies and system sizes, and identify Loschmidt zeros in finite chains. Our analysis reveals the precise conditions on the anisotropy parameter that govern the periodicity of the dynamical observables. In addition to the analytic study, we perform two types of numerical experiments on IBM-Q quantum devices. First, we use the Hadamard test to estimate the Bell-basis expansion coefficients and reconstruct the dynamical states, achieving accurate entanglement entropies and the Loschmidt echo for small systems. Second, we implement Trotter-error-free time-evolution circuits combined with randomized Pauli measurements. Post-processing via statistical correlations and classical shadows yields reliable estimates of the second-order R\'enyi entanglement entropy and the Loschmidt echo, showing satisfactory agreement with exact results. + oai:arXiv.org:2512.03341v2 quant-ph cond-mat.stat-mech - cond-mat.str-el - physics.comp-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yi-Ming Ding, Zenan Liu, Xu Tian, Zhe Wang, Yanzhang Zhu, Zheng Yan - - - Simulating Clifford Circuits with Gaussian Elimination - https://arxiv.org/abs/2511.06127 - arXiv:2511.06127v2 Announce Type: replace -Abstract: Quantum circuits are considered more powerful than classical circuits and require exponential resources to simulate classically. Clifford circuits are a special class of quantum circuits that can be simulated in polynomial time but still show important quantum effects such as entanglement. In this work, we present an algorithm that simulates Clifford circuits by performing Gaussian elimination on a modified adjacency matrix derived from the circuit structure. Our work builds on an ZX-calculus tensor network representation of Clifford circuits that reduces to quantum graph states. We give a concise formula of amplitudes of graph states based on the LDL decomposition of matrices over GF(2), and use it to get efficient algorithms for strong and weak simulation of Clifford circuits using tree-decomposition-based fast LDL algorithm. The complexity of our algorithm matches the state of art for weak graph state simulation and improves the state of art for strong graph state simulation by taking advantage of Strassen-like fast matrix multiplication. Our algorithm is also efficient when computing many amplitudes or samples of a Clifford circuit. Further, our amplitudes formula provides a new characterization of locally Clifford equivalent graph states as well as an efficient protocol to learn graph states with low-rank adjacency matrices. - oai:arXiv.org:2511.06127v2 - quant-ph - cs.NA - math.NA - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yuchen Pang, Edgar Solomonik - - - Hybrid Predictive Quantum Feedback: Extending Qubit Lifetimes Beyond the Wiseman-Milburn Limit - https://arxiv.org/abs/2511.13774 - arXiv:2511.13774v2 Announce Type: replace -Abstract: Amplitude damping fundamentally limits qubit lifetimes by irreversibly leaking energy and information into the environment. Standard Wiseman--Milburn feedback offers only modest improvement because it acts on a single measured quadrature and its corrective drive is degraded by loop delay. We introduce a compact hybrid upgrade with two components: (i) a coherently coupled \emph{ancilla} qubit that receives the homodyne current and feeds back \emph{quantum-coherently} on the system, recovering information from \emph{both} field quadratures and intentionally engineered to decay much faster than the system; and (ii) a lightweight supervised predictor that forecasts the near-future homodyne current, phase-aligning the correction to overcome hardware latency. A Lindblad treatment yields closed-form effective decay rates: the ancilla suppresses the emission channel by a cooperativity factor, while the predictor further suppresses the residual decay in proportion to forecast quality. Using IBM-scale parameters (baseline \(T_1 = 50~\mu\mathrm{s}\)), numerical simulations surpass the W--M limit, achieving \(\sim 3\!-\!4\times\) longer \(T_1\) together with improved population retention and integrated energy. The method is modular and hardware-compatible: ancilla coupling and supervised prediction can be added to existing W--M loops to convert leaked information into a precise, time-advanced corrective drive. We also include a detailed, student-friendly derivation of the effective rates for both ancilla-assisted and prediction-enhanced feedback, making the impact of each design element analytically transparent. - oai:arXiv.org:2511.13774v2 - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ali Abu-Nada, Aryan Iliat, Russell Ceballos - - - On-Chip Levitated Neon Particle Arrays for Robust and Scalable Electron Qubits - https://arxiv.org/abs/2512.00654 - arXiv:2512.00654v2 Announce Type: replace -Abstract: Electron-on-neon (eNe) qubits have recently emerged as a compelling platform for quantum computing, which combines the vacuum isolation advantages of trapped-ion qubits with the scalability of superconducting circuits. In this system, electrons are trapped in vacuum above a solid neon film deposited on superconducting microwave resonators, where they exhibit strong coupling to the resonators, coherence times of ~0.1 ms, and single-qubit gate fidelities exceeding 99.97%. A central challenge, however, is the spontaneous binding of electrons to neon surface bumps. These bumps, originating from substrate roughness, vary in size: electrons on bumps of suitable sizes within the resonator can couple to microwave photons and function as qubits, whereas those on unfavorable bumps remain inactive yet contribute to background charge noise. Moreover, both the bump landscape and the sites where electrons bind differ from run to run, leading to variable qubit characteristics that hinder scalability. To address this challenging issue, we present an on-chip magnetic-levitation architecture in which arrays of solid-neon microparticles are suspended above the processor chip to act as electron carriers. This design eliminates substrate effects while retaining strong qubit-resonator coupling and supporting inter-qubit connectivity. Our analysis further shows that the qubit transition frequency can be tuned across the gigahertz range and its anharmonicity can reach ~0.8 GHz by tuning the resonator bias voltage. Together, these features suggest a promising pathway toward robust, reproducible, and scalable eNe-based quantum computing. - oai:arXiv.org:2512.00654v2 - quant-ph - cond-mat.mes-hall - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sosuke Inui, Yinghe Qi, Yiming Xing, Charles Peretti, Dafei Jin, Wei Guo - - - Enhanced Single-Photon Detector: A framework for Superconducting-Level Performance without cryogenic cooling - https://arxiv.org/abs/2512.01328 - arXiv:2512.01328v2 Announce Type: replace -Abstract: High-performance single-photon detectors (SPDs) are indispensable components for a wide range of quantum optical applications. However, the reliance of state-of-the-art devices on superconducting materials imposes severe technological demands and necessitates challenging operational conditions, such as cryogenics, thereby hindering scalable implementation. To address this, we propose the Enhanced Single-Photon Detector (ESPD) framework, a novel paradigm for achieving high-performance SPDs through the iterative enhancement of conventional room-temperature SPDs. Relying entirely on non-superconducting components and eliminating cryogenic cooling requirements, the ESPD scheme can upgrade a legacy SPD, with detection efficiency (DE) about $59\%$ and dark count rate (DCR) of $10^{-2}$, to a device with superior performance metrics, achieving DE exceeding $93\%$ and DCR below $10^{-9}$. This performance rivals or even surpasses that of state-of-the-art superconducting SPDs, allowing the minimal tolerable channel transmission rate for quantum key distribution (QKD) protocols to be reduced by several orders of magnitude. Although the architecture requires substantial integration effort, the scheme can provide superconducting-level performance without cryogenic cooling, offering a clear path toward the widespread deployment of high-performance SPDs as well as related quantum technologies in infrastructure-constrained environments. - oai:arXiv.org:2512.01328v2 - quant-ph - math-ph - math.MP - math.OC - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hao Shu - - - Polylogarithmic-Depth Quantum Algorithm for Simulating the Extended Hubbard Model on a Two-Dimensional Lattice Using the Fast Multipole Method - https://arxiv.org/abs/2512.03898 - arXiv:2512.03898v3 Announce Type: replace -Abstract: The extended Hubbard model on a two-dimensional lattice captures key physical phenomena, but is challenging to simulate due to the presence of long-range interactions. In this work, we present an efficient quantum algorithm for simulating the time evolution of this model. Our approach, inspired by the fast multipole method, approximates pairwise interactions by interactions between hierarchical levels of coarse-graining boxes. We discuss how to leverage recent advances in two-dimensional neutral atom quantum computing, supporting non-local operations such as long-range gates and shuttling. The resulting circuit depth for a single Trotter step scales polylogarithmically with system size. - oai:arXiv.org:2512.03898v3 - quant-ph - cond-mat.str-el - Tue, 09 Dec 2025 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Yu Wang, Martina Nibbi, Maxine Luo, Isabel Nha Minh Le, Yanbin Chen, J. Ignacio Cirac, Christian B. Mendl + Ching-Tai Huang, Yu-Cheng Lin, Ferenc Igloi A contextual advantage for conclusive exclusion: repurposing the Pusey-Barrett-Rudolph construction https://arxiv.org/abs/2512.04173 - arXiv:2512.04173v2 Announce Type: replace + arXiv:2512.04173v3 Announce Type: replace Abstract: The task of conclusive exclusion for a set of quantum states is to find a measurement such that for each state in the set, there is an outcome that allows one to conclude with certainty that the state in question was not prepared. Defining classicality of statistics as realizability by a generalized-noncontextual ontological model, we show that there is a quantum-over-classical advantage for how well one can achieve conclusive exclusion. This is achieved in an experimental scenario motivated by the construction appearing in the Pusey-Barrett-Rudolph theorem. We derive noise-robust noncontextuality inequalities bounding the conclusiveness of exclusion, and describe a quantum violation of these. Finally, we show that this bound also constitutes a classical causal compatibility inequality within the bilocality scenario, and that its violation in quantum theory yields a novel possibilistic proof of a quantum-classical gap in that scenario. - oai:arXiv.org:2512.04173v2 + oai:arXiv.org:2512.04173v3 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by-nc-sa/4.0/ Y\`il\`e Y\=ing, David Schmid, Robert W. Spekkens - Shape dependence of entanglement negativity and mutual information in quantum Hall and critical systems - https://arxiv.org/abs/2208.12819 - arXiv:2208.12819v2 Announce Type: replace-cross -Abstract: We study two entanglement measures in a large family of isotropic many-body states including incompressible quantum Hall liquids and quantum critical systems: the logarithmic negativity (LN), and mutual information (MI). For pure states, obtained for example from a bipartition at zero temperature, these provide distinct characterizations of the entanglement present between two spatial subregions, while for mixed states (such as at finite temperature) only the LN remains a good entanglement measure. Our focus is on regions that have corners, either adjacent or tip-touching. We first obtain general non-perturbative properties regarding the geometrical dependence of the LN and MI. A close similarity is observed with mutual charge fluctuations, where super-universal angle dependence holds allowing for explicit checks. For the MI, we make stronger statements due to strong subadditivity. We also give ramifications of our general analysis to conformal field theories (CFTs) in two spatial dimensions. We then explicitly verify these properties with integer quantum Hall states. To do so we develop two independent approaches to obtain the fermionic LN, which takes into account Fermi statistics: an overlap-matrix method, and a real-space lattice discretization. At finite temperature, we find a rapid decrease of the LN well inside the cyclotron gap at integer fillings. We further show that the LN decays faster compared to the MI at high temperatures. - oai:arXiv.org:2208.12819v2 - cond-mat.str-el - cond-mat.mes-hall - cond-mat.stat-mech - hep-th - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Chia-Chuan Liu, Juliette Geoffrion, William Witczak-Krempa - - - Generalized Gibbs Ensemble from Eigenstate Entanglement Hamiltonian - https://arxiv.org/abs/2402.00939 - arXiv:2402.00939v2 Announce Type: replace-cross -Abstract: Relaxed quantum systems with conservation laws are believed to be approximated by the Generalized Gibbs Ensemble (GGE), which incorporates the constraints of certain conserved quantities serving as integrals of motion. By drawing an analogy between eigenstate reduced density matrix and GGE, we conjecture that a natural set of conserved quantities for GGE can emerge from the reduced density matrices of properly chosen eigenstates by the entanglement Hamiltonian superdensity matrix (EHSM) framework, and we demonstrate this explicitly for models mappable to free fermions. The framework proposes that such conserved quantities are linear superpositions of eigenstate entanglement Hamiltonians of a larger auxiliary system, where the eigenstates are Fock states occupying what we call the common eigenmodes, which remain eigenmodes when truncated within the physical subsystem. For 1D homogeneous free fermions with (anti-)periodic boundary conditions, which maps to 1D hardcore bosons with nearest neighbor hoppings, these conserved quantities lead to a non-Abelian GGE, which predicts the relaxation of both fermion and boson bilinears more accurately than the conventional Abelian GGE. Generalization of this framework may provide novel numerical insights for quantum integrability. - oai:arXiv.org:2402.00939v2 - cond-mat.stat-mech - cond-mat.quant-gas - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.1103/dn82-y159 - Phys. Rev. Lett. 135, 233402 (2025) - Hao Chen, Biao Lian - - - Ultrasound evidence for multicomponent superconducting order parameter in Ba$_{1-x}$K$_x$Fe$_2$As$_2$ with electron quadrupling phase - https://arxiv.org/abs/2404.03020 - arXiv:2404.03020v3 Announce Type: replace-cross -Abstract: Experiments have pointed to the formation of the electron quadrupling condensate in Ba$_{1-x}$K$_x$Fe$_2$As$_2$ at $x \sim 0.8$. The state spontaneously breaks time-reversal symmetry and is sandwiched between two critical points, separating it from the broken time-reversal symmetry (BTRS) superconducting state at $T_{\rm c}^{U(1)}$ and normal-metal state at $T_{\rm c}^{\rm Z2}$. We report a theory of the acoustic effects spectroscopy of systems with an electron quadrupling phase based on ultrasound-velocity measurements. We show that the experimental results are consistent with BTRS superconductivity at $x \sim 0.8$, fulfilling the necessary condition for the formation of electron quadrupling in Ba$_{1-x}$K$_x$Fe$_2$As$_2$. We provide the theoretical basis and the experimental strategy to study the order parameter symmetry of emerging quadrupling condensates in superconductors. - oai:arXiv.org:2404.03020v3 - cond-mat.supr-con - cond-mat.str-el + A Framework for Quantum Simulations of Energy-Loss and Hadronization in Non-Abelian Gauge Theories: SU(2) Lattice Gauge Theory in 1+1D + https://arxiv.org/abs/2512.05210 + arXiv:2512.05210v2 Announce Type: replace +Abstract: Simulations of energy loss and hadronization are essential for understanding a range of phenomena in non-equilibrium strongly-interacting matter. We establish a framework for performing such simulations on a quantum computer and apply it to a heavy quark moving across a modest-sized 1+1D SU(2) lattice of light quarks. Conceptual advances with regard to simulations of non-Abelian versus Abelian theories are developed, allowing for the evolution of the energy in light quarks, of their local non-Abelian charge densities, and of their multi-partite entanglement to be computed. The non-trivial action of non-Abelian charge operators on arbitrary states suggests mapping the heavy quarks to qubits alongside the light quarks, and limits the heavy-quark motion to discrete steps among spatial lattice sites. Further, the color entanglement among the heavy quarks and light quarks is implemented using hadronic operators, and Domain Decomposition is shown to be effective in quantum state preparation. Scalable quantum circuits that account for the heterogeneity of non-Abelian charge sectors across the lattice are used to prepare the interacting ground-state wavefunction in the presence of heavy quarks. The discrete motion of heavy quarks between adjacent spatial sites is implemented using fermionic SWAP operations. Quantum simulations of the dynamics of a system on $L=3$ spatial sites are performed using IBM's ${\tt ibm\_pittsburgh}$ quantum computer using 18 qubits, for which the circuits for state preparation, motion, and one second-order Trotter step of time evolution have a two-qubit depth of 398. A suite of error mitigation techniques are used to extract the observables from the simulations, providing results that are in good agreement with classical simulations. The framework presented here generalizes straightforwardly to other non-Abelian groups, including SU(3) for quantum chromodynamics. + oai:arXiv.org:2512.05210v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1038/s41535-025-00819-7 - npj Quantum Materials volume 10, Article number: 107 (2025) - Chris Halcrow, Ilya Shipulin, Federico Caglieris, Yongwei Li, Joachim Wosnitza, Hans-Henning Klauss, Sergei Zherlitsyn, Vadim Grinenko, Egor Babaev + hep-lat + hep-ph + nucl-th + Wed, 10 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Zhiyao Li, Marc Illa, Martin J. Savage - Strong-field resummed heat kernels and effective actions: inhomogeneous fields - https://arxiv.org/abs/2410.11364 - arXiv:2410.11364v2 Announce Type: replace-cross -Abstract: We study the strong-field limit of a theory involving a quantum scalar field coupled to a vector background, which can be either an electromagnetic field or a non-gauge field coupled through the first derivative term. Our approach consists in obtaining resummed expressions for the associated heat kernels, from which we derive the corresponding resummed effective actions. These results allow us to discuss the effect of pair creation. Finally, we conjecture that resummations for more general theories should be possible. - oai:arXiv.org:2410.11364v2 - hep-th - math-ph - math.MP + Quantum Correlation Assisted Cooling of Microwave Cavities Below the Ambient Temperature + https://arxiv.org/abs/2512.06996 + arXiv:2512.06996v2 Announce Type: replace +Abstract: We develop a theoretical framework for cooling a microwave cavity mode using a Poisson stream of internally correlated pairs of two-level systems and analyze its performance under realistic dissipation. Starting from a Lindblad model of a phonon-tethered cavity interacting with sequentially injected atom pairs, we derive closed-form expressions for the steady-state cavity occupation and effective temperature. Two coupling geometries are examined: a one-atom configuration, where only one member of each pair interacts with the cavity, and a two-atom configuration, where both atoms couple collectively. The single-atom model enables cooling below the phonon bath but not below the reservoir temperature, whereas the two-atom scheme exhibits enhanced refrigeration - pair correlations modify the cavity's upward and downward transition rates so that the steady-state temperature can fall well below that of the reservoir for weak phonon damping. We map the parameter space including detuning, coupling strength, damping, and intra-pair exchange, identifying cooling valleys near resonance and the crossover between reservoir- and phonon-dominated regimes. The two-atom configuration thus realizes a genuine quantum-enhanced cooling mechanism absent in the single-atom case. We further outline an experimental implementation using two superconducting qubits repeatedly prepared, coupled, and reset inside a 3D cavity. Realistic reset and flux-tuning protocols support MHz-rate interaction cycles, enabling engineered reservoirs to impose cavity temperatures of 50-120 mK even when the cryostat is at ~1 K, offering a pathway to autonomous, on-chip refrigeration of microwave modes in scalable quantum hardware. + oai:arXiv.org:2512.06996v2 quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross + cond-mat.mes-hall + Wed, 10 Dec 2025 00:00:00 -0500 + replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - S. A. Franchino-Vi\~nas, C. Garc\'ia-P\'erez, F. D. Mazzitelli, S. Pla, V. Vitagliano, U. Wainstein-Haimovichi + Daryoosh Vashaee, Jahanfar Abouie - Machine learning of the Ising model on a spherical Fibonacci lattice - https://arxiv.org/abs/2410.12007 - arXiv:2410.12007v3 Announce Type: replace-cross -Abstract: We investigate the Ising model on a spherical surface, utilizing a Fibonacci lattice to approximate uniform coverage. This setup poses challenges in achieving consistent lattice distribution across the sphere for comparison with planar models. We employ Monte Carlo simulations, principal component analysis (PCA), graph convolutional networks (GCNs) to study spin configurations across a range of temperatures and to determine phase transition temperatures. The Fibonacci lattice, despite its uniformity, contains irregular sites that influence spin behavior. In the ferromagnetic case, sites with fewer neighbors exhibit a higher tendency for spin flips at low temperatures, though this effect weakens as temperature increases, leading to a higher phase transition temperature than in the planar Ising model. In the antiferromagnetic case, lattice irregularities induce geometric frustration, resulting in highly degenerate ground states and the phase transition temperature lower than the planar square lattice. Phase transition temperatures are derived through specific heat, magnetic susceptibility analysis and GCNs predictions, yielding $T_c$ values for both ferromagnetic and antiferromagnetic scenarios. This work emphasizes the impact of the Fibonacci lattice's geometric properties-namely curvature and connectivity-on spin interactions in non-planar systems, with relevance to microgravity environments. - oai:arXiv.org:2410.12007v3 - physics.comp-ph + Quantum-Plasmonic Dynamics Modeled via a Modified Langevin Noise Formalism: Numerical Studies of Single-Photon Emission and Two-Photon Interference + https://arxiv.org/abs/2205.03388 + arXiv:2205.03388v2 Announce Type: replace-cross +Abstract: Recent studies have established and rigorously validated a modified Langevin noise formalism that enables first-principles quantization of electromagnetic fields in open and dissipative environments [1,2,3]. Building on this foundation, a fully quantum-mechanical multimode Jaynes-Cummings framework has been developed and verified, providing an accurate description of atom--field interactions in lossy and radiative systems [4]. In this work, we explore the potential of this formalism for nanophotonic applications by modeling representative quantum-plasmonic dynamics. In particular, we present detailed numerical examples for (i) two-photon interference mediated by a quantum plasmonic beam splitter, and (ii) non-Markovian dynamics of an atom located in plasmonic antennas and directional control of out-coupled single-photon fields. These results demonstrate that the proposed modeling approach can be directly used to guide the design and optimization of plasmonic single-photon sources and beam-splitting structures. Moreover, the framework is broadly applicable to the analysis of linear optical components and cavity quantum electrodynamics problems in open and dissipative photonic integrated circuits. + oai:arXiv.org:2205.03388v2 + physics.optics quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1088/1367-2630/ae21fc - New J. Phys. 27 124601(2025) - Zheng Zhou, Chen-Hui Song, Xu-Yang Hou, Hao Guo + Jisang Seo, Hyunwoo Choi, Thomas E Roth, Jie Zhu, Weng C Chew, Dong-Yeop Na - Spectral decomposition and high-accuracy Greens functions: Overcoming the Nyquist-Shannon limit via complex-time Krylov expansion - https://arxiv.org/abs/2411.09680 - arXiv:2411.09680v3 Announce Type: replace-cross -Abstract: The accurate computation of low-energy spectra of strongly correlated quantum many-body systems, typically accessed via Green's functions, is a long-standing problem posing enormous challenges to numerical methods. When the spectral decomposition is obtained from Fourier transforming a time series, the Nyquist-Shannon theorem limits the frequency resolution $\Delta \omega$ according to the numerically accessible time domain size $T$ via $\Delta \omega = 2\pi/T$. In tensor network methods, increasing the domain size is exponentially hard due to the ubiquitous spread of correlations, limiting the frequency resolution and thereby restricting this ansatz class mostly to one-dimensional systems with small quasi-particle velocities. Here, we show how this limitation can be overcome by augmenting the time series with complex-time Krylov states. At the example of the critical $S-1/2$ Heisenberg model and light bipolarons in the two-dimensional Su-Schrieffer-Heeger model, we demonstrate the enormous improvements in accuracy, which can be achieved using this method. - oai:arXiv.org:2411.09680v3 + Triangular lattice models of the Kalmeyer-Laughlin spin liquid from coupled wires + https://arxiv.org/abs/2502.13223 + arXiv:2502.13223v2 Announce Type: replace-cross +Abstract: Chiral spin liquids (CSLs) are exotic phases of interacting spins in two dimensions, characterized by long-range entanglement and fractional excitations. We construct a local Hamiltonian on the triangular lattice that stabilizes the Kalmeyer-Laughlin CSL without requiring fine-tuning. Our approach employs coupled-wire constructions and introduces a lattice duality to construct a solvable chiral sliding Luttinger liquid, which is driven toward the CSL phase by generic perturbations. By combining symmetry analysis and bosonization, we make sharp predictions for the ground states on quasi-one-dimensional cylinders and tori, which exhibit a fourfold periodicity in the circumference. Extensive tensor network simulations demonstrating ground-state degeneracies, fractional quasiparticles, nonvanishing long-range order parameters, and entanglement signatures confirm the emergence of the CSL in the lattice Hamiltonian. + oai:arXiv.org:2502.13223v2 cond-mat.str-el quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sebastian Paeckel - - - Perturbative distinguishability of black hole microstates from AdS/CFT correspondence - https://arxiv.org/abs/2504.08402 - arXiv:2504.08402v2 Announce Type: replace-cross -Abstract: We establish direct evidence for the perturbative distinguishability between black hole microstates and thermal states using the AdS/CFT correspondence. In two-dimensional holographic conformal field theories, we obtain the subsystem fidelity and quantum Jensen-Shannon divergence, both of which provide rigorous lower and upper bounds for subsystem trace distance. This result demonstrates that perturbative quantum gravity corrections break semiclassical indistinguishability, thereby supporting the recovery of information even from a small amount of the Hawking radiation. - oai:arXiv.org:2504.08402v2 - hep-th - cond-mat.stat-mech - gr-qc - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/w5dn-jvfs - Phys. Rev. D 112 (2025) 12, L121901 - Jiaju Zhang - - - Bootstrapping Shape Invariance: Numerical Bootstrap as a Detector of Solvable Systems - https://arxiv.org/abs/2504.08586 - arXiv:2504.08586v3 Announce Type: replace-cross -Abstract: Determining the solvability of a given quantum mechanical system is generally challenging. We discuss that the numerical bootstrap method can help us to solve this question in one-dimensional quantum mechanics. We show that the bootstrap method can derive exact energy eigenvalues in systems with shape invariance, which is a sufficient condition for solvability and which many solvable systems satisfy. The information of the annihilation operators is also obtained naturally, and thus the bootstrap method tells us why the system is solvable. We numerically demonstrate this explicitly for shape invariant potentials: harmonic oscillators, Morse potentials, Rosen-Morse potentials and hyperbolic Scarf potentials. Therefore, the numerical bootstrap method can determine the solvability of a given unknown system if it satisfies shape invariance. - oai:arXiv.org:2504.08586v3 - hep-th - hep-lat - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1093/ptep/ptaf139 - Prog Theor Exp Phys (2025) - Yu Aikawa, Takeshi Morita + 10.1103/3nfx-fkfg + Phys. Rev. B 112, 224415 (2025) + Tingyu Gao, Niklas Tausendpfund, Erik L. Weerda, Jan Naumann, Matteo Rizzi, David F. Mross - On the Schr\"odingerization method for linear non-unitary dynamics with optimal dependence on matrix queries - https://arxiv.org/abs/2505.00370 - arXiv:2505.00370v4 Announce Type: replace-cross -Abstract: The Schr\"odingerization method converts linear partial and ordinary differential equations with non-unitary dynamics into systems of Schr\"odinger-type equations with unitary evolution. It does so via the so-called warped phase transformation that maps the original equation into a Schr\"odinger-type equation in one higher dimension \cite{Schrshort,JLY22SchrLong}. The original proposal used a particular initial function in the auxiliary space that did not achieve optimal scaling in precision. Here we show that, by choosing smoother initial functions in auxiliary space, Schr\"odingerization \textit{can} in fact achieve near optimal and even optimal scaling in matrix queries. We construct three necessary criteria that the initial auxiliary state must satisfy to achieve optimality. This paper presents detailed implementation of four smooth initializations for the Schr\"odingerization method: (a) the error function and related functions, (b) the cut-off function, (c) the higher-order polynomial interpolation, and (d) Fourier transform methods. Method (a) achieves optimality and methods (b), (c) and (d) can achieve near-optimality. A detailed analysis of key parameters affecting time complexity is conducted. - oai:arXiv.org:2505.00370v4 - math.NA - cs.NA + Quantum-Accelerated Wireless Communications: Concepts, Connections, and Implications + https://arxiv.org/abs/2506.20863 + arXiv:2506.20863v2 Announce Type: replace-cross +Abstract: Quantum computing is poised to redefine the algorithmic foundations of communication systems. While quantum superposition and entanglement enable quadratic or exponential speedups for specific problems, identifying use cases where these advantages yield engineering benefits is still nontrivial. This article presents the fundamentals of quantum computing in a style familiar to the communications society, outlining the current limits of fault-tolerant quantum computing and clarifying a mathematical harmony between quantum and wireless systems, which makes the topic more enticing to wireless researchers. Based on a systematic review of pioneering and state-of-the-art studies indicating speedup opportunities, we distill common design trends for the research and development of quantum-accelerated communication systems and highlight lessons learned. The key insight is that quantum algorithms, including their gate-level realizations, can benefit from the design intuition applied in communication engineering. This article aims to catalyze interdisciplinary research at the frontier of quantum information processing and future communication systems. + oai:arXiv.org:2506.20863v2 + eess.SP quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Shi Jin, Nana Liu, Chuwen Ma, Yizhe Peng, Yue Yu + http://creativecommons.org/licenses/by/4.0/ + 10.1109/MCOM.001.2500390 + IEEE Communications Magazine, 2025 + Naoki Ishikawa, Giuseppe Thadeu Freitas de Abreu, Petar Popovski, Robert W. Heath Jr - Ultra-long-living magnons in the quantum limit - https://arxiv.org/abs/2505.22773 - arXiv:2505.22773v3 Announce Type: replace-cross -Abstract: Solid-state platforms based on bosonic quasiparticles offer a compelling route toward on-chip quantum information technologies scalable to nanometer dimensions. Coherence time, a key figure of merit for any quantum system, is fundamentally limited by the lifetime of quasiparticles that store quantum information. For magnons - bosonic excitations of collective magnetization dynamics - it has long been reported that their lifetime does not exceed a few hundred nanoseconds, placing a stringent constraint on their use in quantum architectures. Here, we demonstrate magnon lifetimes exceeding 18 {\mu}s. Experiments performed on single-crystal yttrium iron garnet spheres cooled to 30 mK reveal relaxation times of short-wavelength magnons nearly two orders of magnitude longer than previously observed. These findings overturn the established view of magnon dissipation limits, positioning magnons as viable, long-lived information carriers for solid-state quantum computing. - oai:arXiv.org:2505.22773v3 - cond-mat.mtrl-sci + Disentangling tensor product structures + https://arxiv.org/abs/2506.21173 + arXiv:2506.21173v2 Announce Type: replace-cross +Abstract: As a contribution to the field of quantum mereology, we study how a change of tensor product structure in a finite-dimensional Hilbert space affects its entanglement properties. In particular, we ask whether, given a time-evolving state, there exists a tensor product structure in which no entanglement is generated. We give a concrete, constructive example of disentangling tensor product structure in the case of a C-NOT gate evolution between two qbits, before showing that this cannot be achieved for most time-evolving quantum states. + oai:arXiv.org:2506.21173v2 + math-ph + math.MP quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - Rostyslav O. Serha, Kaitlin H. McAllister, Fabian Majcen, Sebastian Knauer, Timmy Reimann, Carsten Dubs, Gennadii A. Melkov, Alexander A. Serga, Vasyl S. Tyberkevych, Andrii V. Chumak, Dmytro A. Bozhko + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Antoine Soulas - Rethinking LLM Training through Information Geometry and Quantum Metrics - https://arxiv.org/abs/2506.15830 - arXiv:2506.15830v4 Announce Type: replace-cross -Abstract: Optimization in large language models (LLMs) unfolds over high-dimensional parameter spaces with non-Euclidean structure. Information geometry frames this landscape using the Fisher information metric, enabling more principled learning via natural gradient descent. Though often impractical, this geometric lens clarifies phenomena such as sharp minima, generalization, and observed scaling laws. We argue that curvature-based approaches deepen our understanding of LLM training. Finally, we speculate on quantum analogies based on the Fubini-Study metric and Quantum Fisher Information, hinting at efficient optimization in quantum-enhanced systems. - oai:arXiv.org:2506.15830v4 - cs.CL + Vacuum Energy and Topological Mass from a Constant Magnetic Field and Boundary Conditions in Coupled Scalar Field Theories + https://arxiv.org/abs/2508.15121 + arXiv:2508.15121v2 Announce Type: replace-cross +Abstract: We investigate the combined effects of a uniform magnetic field and boundary conditions on vacuum energy and topological mass generation in a coupled scalar field theory. The system consists of a real scalar field, subject to Dirichlet boundary conditions, interacting via self- and cross-couplings with a gauge-coupled complex scalar field obeying mixed boundary conditions between two perfectly reflecting parallel plates. The magnetic field induces Landau quantization, leading to novel contributions. Employing zeta-function regularization within the effective potential formalism, we derive the renormalized effective potential up to second order in the coupling constants without imposing a vanishing magnetic field in the renormalization scheme. Our renormalization approach preserves magnetic contributions while properly removing divergences, enabling a consistent treatment of finite-size corrections, magnetic effects, and interaction terms. We compute the vacuum energy per unit area of the plates, analyze the emergence of a topological mass from boundary and magnetic contributions, and evaluate the first-order coupling-constant corrections at two-loop order. Detailed asymptotic analysis are presented for both weak- and strong-field regimes, revealing exponential suppression at high magnetic fields and nontrivial polynomial and logarithmic behavior in the weak-field limit. + oai:arXiv.org:2508.15121v2 + hep-th + math-ph + math.MP quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Riccardo Di Sipio + A. J. D. Farias Junior, Andrea Erdas, Herondy F. Santana Mota - Double Supersolid Phase in a Bosonic t-J-V Model with Rydberg Atoms - https://arxiv.org/abs/2506.16820 - arXiv:2506.16820v4 Announce Type: replace-cross -Abstract: Recent advances in Rydberg tweezer arrays bring novel opportunities for programmable quantum simulations beyond previous capabilities. In this work, we investigate a bosonic t-J-V model currently realized with Rydberg atoms. Through large-scale quantum Monte Carlo simulations, we uncover an emergent double supersolid (DSS) phase with the coexistence of two superfluids and crystalline order. Tunable long-range tunneling and repulsive hole-hole interactions enable a rich phase diagram featuring a double superfluid phase, a DSS phase, and an antiferromagnetic insulator. Intriguingly, within the DSS regime we observe an unconventional thermal enhancement of crystalline order. Our results establish the bosonic t-J-V model as a promising and experimentally accessible platform for exploring exotic quantum phases in Rydberg atom arrays. - oai:arXiv.org:2506.16820v4 - cond-mat.quant-gas + Subdimensional entanglement entropy: from geometric-topological response to entanglement-induced mixed-state landscape + https://arxiv.org/abs/2510.15766 + arXiv:2510.15766v2 Announce Type: replace-cross +Abstract: A growing body of examples reveals that topology and geometry are deeply intertwined in shaping universal properties of quantum matter, as seen in fracton orders with size-dependent topological ground-state degeneracy and in cluster states with spurious topological entanglement entropy. We introduce the \textit{subdimensional entanglement entropy} (SEE), defined on \textit{subdimensional entanglement subsystems} (SESs) embedded in the bulk, as a direct probe of this intertwinement. By virtually tuning SES dimension, geometry and topology, the subleading components of SEE show sharply distinct geometric and topological responses in cluster states, $\mathbb{Z}_q$ topological orders, and fracton orders. Further viewing the SES reduced density matrix as a mixed state on the SES manifold, we establish an exact correspondence between stabilizers and mixed-state symmetries, distinguishing \textit{strong} from \textit{weak} classes. Nontrivial SEE enforces weak symmetries to act as \textit{transparent patch operators} of strong ones, together forming \textit{transparent composite symmetries} that are robust against finite depth quantum circuits. Due to the presence of transparent patch operators, each $D$-dimensional SES holographically encodes a $(D+1)$-dimensional topological order. Thus, SEE simultaneously accesses various forefront directions, providing a unified and versatile nexus linking phenomena previously regarded as distinct. + oai:arXiv.org:2510.15766v2 cond-mat.str-el - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/fg7f-zvtt - Kuangjie Chen, Yang Qi, Zheng Yan, Xiaopeng Li - - - Spontaneous Quantum Turbulence in a Newborn Bose-Einstein Condensate via the Kibble-Zurek Mechanism - https://arxiv.org/abs/2506.21670 - arXiv:2506.21670v2 Announce Type: replace-cross -Abstract: The Kibble-Zurek mechanism (KZM) predicts the spontaneous formation of topological defects in a continuous phase transition driven at a finite rate. We propose the generation of spontaneous quantum turbulence (SQT) via the KZM during Bose-Einstein condensation induced by a thermal quench. Using numerical simulations of the stochastic projected Gross-Pitaevskii equation in two spatial dimensions, we describe the formation of a newborn Bose-Einstein condensate proliferated by quantum vortices. We establish the nonequilibrium universality of SQT through the Kibble-Zurek and Kolmogorov scaling of the incompressible kinetic energy. - oai:arXiv.org:2506.21670v2 - cond-mat.quant-gas cond-mat.stat-mech + hep-th quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Seong-Ho Shinn, Matteo Massaro, Mithun Thudiyangal, Adolfo del Campo - - - Generalized Probabilistic Approximate Optimization Algorithm - https://arxiv.org/abs/2507.07420 - arXiv:2507.07420v3 Announce Type: replace-cross -Abstract: We introduce a generalized \textit{Probabilistic Approximate Optimization Algorithm (PAOA)}, a classical variational Monte Carlo framework that extends and formalizes prior work by Weitz \textit{et al.}~\cite{Combes_2023}, enabling parameterized and fast sampling on present-day Ising machines and probabilistic computers. PAOA operates by iteratively modifying the couplings of a network of binary stochastic units, guided by cost evaluations from independent samples. We establish a direct correspondence between derivative-free updates and the gradient of the full Markov flow over the exponentially large state space, showing that PAOA admits a principled variational formulation. Simulated annealing emerges as a limiting case under constrained parameterizations, and we implement this regime on an FPGA-based probabilistic computer with on-chip annealing to solve large 3D spin-glass problems. Benchmarking PAOA against QAOA on the canonical 26-spin Sherrington-Kirkpatrick model with matched parameters reveals superior performance for PAOA. We show that PAOA naturally extends simulated annealing by optimizing multiple temperature profiles, leading to improved performance over SA on heavy-tailed problems such as SK-L\'evy. - oai:arXiv.org:2507.07420v3 - cond-mat.dis-nn - cs.LG - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1038/s41467-025-67187-5 - Abdelrahman S. Abdelrahman, Shuvro Chowdhury, Flaviano Morone, Kerem Y. Camsari + Meng-Yuan Li, Peng Ye - Unconventional hybrid-order topological insulators - https://arxiv.org/abs/2507.22666 - arXiv:2507.22666v2 Announce Type: replace-cross -Abstract: Exploring novel topological matters with exotic quantum states has always been a core issue in the field of condensed matter physics, which can update the understanding of topological phases and broaden the classification of topological materials. Here, we report a class of unconventional hybrid-order topological insulators (HyOTIs), which simultaneously host various different higher-order topological states in a single band gap. Such topological states exhibit a unique bulk-boundary correspondence that is different from the well-known first-order topological states, higher-order topological states, and the coexistence of both. Particularly, we develop a generic surface theory to precisely capture them and discover a three-dimensional unconventional HyOTI protected by inversion symmetry, which renders both helical and corner topological states and exhibits an unprecedented bulk-edge-corner correspondence. By adjusting the parameters of the system, we also observe the nontrivial phase transitions between the inversion-symmetric HyOTI and other conventional phases. We further propose a circuit-based experimental scheme to detect these interesting results. Remarkably, we demonstrate that a modified tight-binding model of bismuth can support the unconventional HyOTI, suggesting a possible route for its material realization. This work shall significantly advance the research of hybrid topological states in both theory and experiment. - oai:arXiv.org:2507.22666v2 + Adiabatic Electron Transfer in the Barrierless and Marcus-Inverted Regimes + https://arxiv.org/abs/2511.01909 + arXiv:2511.01909v3 Announce Type: replace-cross +Abstract: Here it is shown that in the adiabatic limit of condensed-phase electron transfer, the onset of barrierless transition occurs at a lower driving force than predicted by the non-adiabatic Marcus formulation. Furthermore, in the adiabatic limit of the Marcus-inverted region, the standard mechanism of electron transfer becomes topologically forbidden. This behavior arises from a topological change in the mapping between the adiabatic and diabatic electronic surfaces, emerging precisely at the onset of the Marcus-inverted region. In this case, alternative mechanisms such as tunneling and non-radiative decay may dominate the rate, typically orders of magnitude slower than the rate calculated from Marcus theory. + oai:arXiv.org:2511.01909v3 + physics.chem-ph cond-mat.mes-hall cond-mat.mtrl-sci - cond-mat.str-el - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/zpcc-59kv - Phys. Rev. B 112, L241103 (2025) - Wei Jia, Yuping Tian, Huanhuan Yang, Xiangru Kong, Zhi-Hao Huang, Wei-Jiang Gong, Jun-Hong An - - - Density Operator Expectation Maximization - https://arxiv.org/abs/2507.22786 - arXiv:2507.22786v2 Announce Type: replace-cross -Abstract: Machine learning with density operators, the mathematical foundation of quantum mechanics, is gaining prominence with rapid advances in quantum computing. Generative models based on density operators cannot yet handle tasks that are routinely handled by probabilistic models. The progress of latent variable models, a broad and influential class of probabilistic unsupervised models, was driven by the Expectation-Maximization framework. Deriving such a framework for density operators is challenging due to the non-commutativity of operators. To tackle this challenge, an inequality arising from the monotonicity of relative entropy is demonstrated to serve as an evidence lower bound for density operators. A minorant-maximization perspective on this bound leads to Density Operator Expectation Maximization (DO-EM), a general framework for training latent variable models defined through density operators. Through an information-geometric argument, the Expectation step in DO-EM is shown to be the Petz recovery map. The DO-EM algorithm is applied to Quantum Restricted Boltzmann Machines, adapting Contrastive Divergence to approximate the Maximization step gradient. Quantum interleaved Deep Boltzmann Machines and Quantum Gaussian-Bernoulli Restricted Boltzmann Machines, new models introduced in this work, outperform their probabilistic counterparts on generative tasks when trained with similar computational resources and identical hyperparameters. - oai:arXiv.org:2507.22786v2 - cs.LG - quant-ph - stat.ML - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Adit Vishnu, Abhay Shastry, Dhruva Kashyap, Chiranjib Bhattacharyya - - - Spin-liquid and spin-glass behavior in quantum spin models with all-to-all p-spin interactions - https://arxiv.org/abs/2508.08154 - arXiv:2508.08154v2 Announce Type: replace-cross -Abstract: Spin-liquid and spin-glass states represent two distinct phases of disordered quantum spin systems. These states are, in principle, distinguished by quantum-entangled fluctuations and spin freezing, but identifying each state and characterizing the transition between them remains challenging. Here, we systematically explore the relationship between the spin-liquid and spin-glass states using a model with all-to-all random interactions among p spins, which interpolates between the Ising-like one-component, XY-like two-component, and isotropic three-component cases. By analyzing the system-size N dependence of the Edwards-Anderson order parameter and the density of states, we identify the transition from the spin liquid to the spin glass for various values of p. We show that the phase diagrams for different p can be unified through a scaling with N/p2, revealing that increasing anisotropy in the interactions systematically suppresses the spin-liquid phase and extends the spin-glass regime. Furthermore, we examine the competition between multiple-spin interactions and anisotropy under an external magnetic field in the isotropic case, and find that the spin-liquid phase transitions into the spin-glass phase before entering a quantum paramagnetic phase. Our findings provide insights into quantum disordered phases and the transitions between them. - oai:arXiv.org:2508.08154v2 - cond-mat.str-el quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - 10.1103/r5d6-2cby - Phys. Rev. B 112, 214204 (2025) - Shusei Wadashima, Yukitoshi Motome + Ethan Abraham - Witt Groups and Bulk-Boundary Correspondence for Stabilizer States - https://arxiv.org/abs/2509.10418 - arXiv:2509.10418v2 Announce Type: replace-cross -Abstract: We establish a bulk--boundary correspondence for translation-invariant stabilizer states in arbitrary spatial dimension, formulated in the framework of modules over Laurent polynomial rings. To each stabilizer state restricted to half-space geometry we associate a boundary operator module. Boundary operator modules provide examples of quasi-symplectic modules, which are objects of independent mathematical interest. In their study, we use ideas from algebraic L-theory in a setting involving non-projective modules and non-unimodular forms. Our results about quasi-symplectic modules in one spatial dimension allow us to resolve the conjecture that every stabilizer state in two dimensions is characterized by a corresponding abelian anyon model with gappable boundary. Our techniques are also applicable beyond two dimensions, such as in the study of fractons. - oai:arXiv.org:2509.10418v2 + Dynamics generated by spatially growing derivations on quasi-local algebras + https://arxiv.org/abs/2511.02941 + arXiv:2511.02941v2 Announce Type: replace-cross +Abstract: We prove global existence and uniqueness of dynamics on the quasi-local algebra $\mathcal{A}$ of a quantum lattice system for spatially growing derivations $\mathcal{L}_\Phi = \sum_x [ \Phi_x , \cdot ]$. Existing results assume that the local terms $\Phi_x\in\mathcal{A}$ of the generator are uniformly bounded in space with respect to appropriate weighted norms $\lVert \Phi_x \rVert_{G,x}$. Analogous to the global existence result for first order ODEs, we show that global existence and uniqueness persist if the size of the local terms $\lVert \Phi_x \rVert_{G,x}$ grows at most linearly in space. This considerably enlarges the class of derivations known to have well-defined dynamics. Moreover, we obtain Lieb-Robinson bounds with exponential light cones for such dynamics. + For the proof, we assume Lieb-Robinson bounds with linear light cones for dynamics, whose generators have uniformly bounded local terms. Such bounds are known to hold, for example, if the local terms are of finite range or exponentially localized. + oai:arXiv.org:2511.02941v2 math-ph - cond-mat.str-el - math.AC math.MP quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - B{\l}a\.zej Ruba, Bowen Yang - - - Double-pair Coulomb and Breit photon correction to the correlated relativistic energy - https://arxiv.org/abs/2510.04571 - arXiv:2510.04571v2 Announce Type: replace-cross -Abstract: The simplest, algebraic quantum-electrodynamical corrections, due to the double-negative energy subspace and instantaneous interactions, are computed to the no-pair energy of two-spin-1/2-fermion systems. Numerical results are reported for two-electron atoms with a clamped nucleus and positronium-like genuine two-particle systems. The Bethe-Salpeter equation provides the theoretical framework, and numerical methods have been developed for its equal-time time-slice. In practice, it requires solving a sixteen-component eigenvalue equation with a two-particle Dirac Hamiltonian, including the appropriate interaction. The double-pair corrections can either be included in the interaction part of the eigenvalue equation or treated as a perturbation to the no-pair Hamiltonian. The numerical results have an $\alpha$ fine-structure constant dependence that is in excellent agreement with the known $\alpha^3E_\mathrm{h}\$-order double-pair correction of non-relativistic quantum electrodynamics. - oai:arXiv.org:2510.04571v2 - physics.chem-ph - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/dv76-8rkt - P\'eter Jeszenszki, Edit M\'atyus - - - Bidirectional Nonlinear Optical Tomography: Unbiased Characterization of Off- and On-Chip Coupling Efficiencies - https://arxiv.org/abs/2510.13110 - arXiv:2510.13110v2 Announce Type: replace-cross -Abstract: Accurate evaluation of nonlinear photonic integrated circuits requires separating input and output coupling efficiencies (i.e., $\eta_1$ and $\eta_2$), yet the conventional linear-transmission calibration method recovers only their product (i.e., $\eta_1\,\eta_2$) and therefore introduces systematic bias when inferring on-chip performance from off-chip data. We present bidirectional nonlinear optical tomography (BNOT), a direction-aware metrology that uses forward and backward pumping of complementary nonlinear probes, with process-appropriate detection, to break the ``degeneracy'' of $\eta_1\,\eta_2$ and estimate individual interface efficiencies with tight confidence intervals. The method links off-chip measurements to on-chip quantities through a compact observation model that explicitly incorporates pump fluctuations and detector noise, and it frames efficiency extraction as a joint constrained optimization. Monte Carlo studies show unbiased convergence of the estimated efficiencies to ground truth with low error across realistic operating regimes. Using these efficiency estimates to reconstruct on-chip nonlinear figures of merit yields distributions centered on the true values with reduced variance, whereas conventional ``degenerate'' calibration is biased and can substantially misestimate on-chip performance. BNOT is hardware-compatible and platform-agnostic, and provides unbiased characterization of off- and on-chip coupling efficiencies across nonlinear processes, enabling reproducible, coupling-resolved benchmarking for scalable systems in quantum optics, frequency conversion, and precision metrology. - oai:arXiv.org:2510.13110v2 - physics.optics - nlin.AO - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Bo-Han Wu, Mahmoud Jalali Mehrabad, Dirk Englund - - - On the Capacity of Erasure-prone Quantum Storage with Erasure-prone Entanglement Assistance - https://arxiv.org/abs/2510.17781 - arXiv:2510.17781v2 Announce Type: replace-cross -Abstract: A quantum message is encoded into $N$ storage nodes (quantum systems $Q_1\dots Q_N$) with assistance from $N_B$ maximally entangled bi-partite quantum systems $A_1B_1, \dots, A_{N_B}B_{N_B}$, that are prepared in advance such that $B_1\dots B_{N_B}$ are stored separately as entanglement assistance (EA) nodes, while $A_1\dots A_{N_B}$ are made available to the encoder. Both the storage nodes and EA nodes are erasure-prone. The quantum message must be recoverable given any $K$ of the $N$ storage nodes along with any $K_B$ of the $N_B$ EA nodes. The capacity for this setting is the maximum size of the quantum message, given that the size of each EA node is $\lambda_B$. All node sizes are relative to the size of a storage node, which is normalized to unity. The exact capacity is characterized as a function of $N,K,N_B,K_B, \lambda_B$ in all cases, with one exception. The capacity remains open for an intermediate range of $\lambda_B$ values when a strict majority of the $N$ storage nodes, and a strict non-zero minority of the $N_B$ EA nodes, are erased. As a key stepping stone, an analogous classical storage (with shared-randomness assistance) problem is introduced. A set of constraints is identified for the classical problem, such that classical linear code constructions translate to quantum storage codes, and the converse bounds for the two settings utilize similar insights. In particular, the capacity characterizations for the classical and quantum settings are shown to be identical in all cases where the capacity is settled. - oai:arXiv.org:2510.17781v2 - cs.IT - math.IT - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hua Sun, Syed A. Jafar - - - Heat measurement of quantum interference - https://arxiv.org/abs/2510.23092 - arXiv:2510.23092v2 Announce Type: replace-cross -Abstract: Coherence is a key property of quantum systems, and it plays a central role in the operation and performance of quantum heat engines and refrigerators. Despite its importance for the fundamental understanding in quantum thermodynamics and its technological implications, coherence effects in heat transport have not been observed previously. Here, we measure quantum features in the heat transfer between a qubit and a thermal bath. The system is formed of a driven flux qubit galvanically coupled to a $\lambda/4$ coplanar-waveguide resonator that is coupled to a heat reservoir. This thermal bath is a normal-metal mesoscopic resistor, whose temperature can be measured and controlled. We detect interference patterns in the heat current due to driving-induced coherence. In particular, resonance peaks in the heat transferred to the bath are found at driving frequencies which are integer fractions of the resonator frequency. A selection rule on the even/odd parity of the peaks holds at the qubit symmetry point. We present a theoretical model based on Floquet theory that captures the experimental results. The studied system provides a platform for studying the role of coherence in quantum thermodynamics. Our work opens the possibility to demonstrate a true quantum thermal machine where heat is measured directly. - oai:arXiv.org:2510.23092v2 - cond-mat.mes-hall - cond-mat.supr-con - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Christoforus Dimas Satrya, Aleksandr S. Strelnikov, Luca Magazz\`u, Yu-Cheng Chang, Rishabh Upadhyay, Joonas T. Peltonen, Bayan Karimi, Jukka P. Pekola - - - Quantum Phase Gradient Imaging Using a Nonlocal Metasurface System - https://arxiv.org/abs/2511.09922 - arXiv:2511.09922v4 Announce Type: replace-cross -Abstract: Quantum phase imaging enables the analysis of transparent samples with thickness and refractive index variations in scenarios requiring precise measurements under low-light conditions. Here, we present a compact quantum phase-gradient imaging system integrating a lithium niobate (LiNbO3) metasurface for generating spatially entangled photon pairs and a silicon (Si) metasurface for phase gradient extraction. By leveraging nonlocal resonances, the LiNbO3 metasurface enables efficient spontaneous parametric down-conversion (SPDC) with all-optically angularly tunable emission, while the Si metasurface provides a nearly linear optical transfer function (OTF) that differentiates the photon wavefunction and extracts phase gradients.Experimental proof-of-concept results demonstrate the imaging of up to 25~rad/mm phase gradients, achieving 89% similarity with the reference values. The pixel resolution of the system can be potentially enhanced by orders of magnitude by increasing the metasurface dimensions and resonance quality factor.Our work showcases the application of metasurfaces in both generating and detecting quantum states and establishes a new paradigm for portable quantum phase-gradient imaging, with potential applications in quantum sensing, microscopy, and LiDAR technology. - oai:arXiv.org:2511.09922v4 - physics.optics - quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Jinliang Ren, Jinyong Ma, Katsuya Tanaka, Lukas Wesemann, Ann Roberts, Frank Setzpfandt, Andrey A. Sukhorukov + Stefan Teufel, Marius Wesle, Tom Wessel - Observation of individual vortex penetration in a coplanar superconducting resonator - https://arxiv.org/abs/2512.00790 - arXiv:2512.00790v2 Announce Type: replace-cross -Abstract: We demonstrate the detection and control of individual Abrikosov vortices in superconducting microwave resonators. $\lambda/4$ resonators with a narrowed region near the grounded end acting as a vortex trap were fabricated and studied using microwave transmission spectroscopy at millikelvin temperatures. Sharp stepwise drops in resonance frequency are detected as a function of increasing external magnetic field, attributed to the entry of individual Abrikosov vortices in the narrow region. This interpretation is confirmed by NV center magnetometry revealing discrete vortex entry events on increasing field. Our results establish a method to investigate and manipulate the states of Abrikosov vortices with microwaves. - oai:arXiv.org:2512.00790v2 - cond-mat.supr-con + Collective cluster nucleation dynamics in 2D Ising quantum magnets + https://arxiv.org/abs/2512.04656 + arXiv:2512.04656v2 Announce Type: replace-cross +Abstract: Strongly interacting many-body systems often show collective properties that are non-trivially related to the microscopic degrees of freedom. Collectivity is responsible for intriguing ground state properties, for example, in superconductors. However, collective effects may also govern the non-equilibrium response of quantum systems, not only in condensed matter physics but also in quantum field theories modeling the properties of our universe. Understanding emergent collective dynamics from first principles, in particular in non-perturbative regimes, is therefore one of the central challenges in quantum many-body physics. Here we report on the observation of collective cluster nucleation in 2D quantum Ising systems realized in an atomic Rydberg array. We observe a confined regime in which the steady-state cluster size is energy-dependent and a deconfined regime characterized by kinetically constrained dynamics of cluster nucleation. Our results mark a qualitative leap for quantum simulations with Rydberg arrays and shed light on highly collective non-equilibrium processes in one of the most important textbook models of condensed matter physics with relevance from quantum magnets and the kinetics of glass formers to cosmology. + oai:arXiv.org:2512.04656v2 + cond-mat.quant-gas quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kirill Shulga, Shunsuke Nishimura, Pavel A. Volkov, Ryota Hasegawa, Miu Hirano, Takeyuki Tsuji, Takayuki Iwasaki, Mutsuko Hatano, Kento Sasaki, Kensuke Kobayashi + Philip Osterholz, Fabio Bensch, Shuanghong Tang, Silpa Baburaj Sheela, Igor Lesanovsky, Christian Gro{\ss} - Boltzmann transport theory of magnon-exciton drag - https://arxiv.org/abs/2512.05835 - arXiv:2512.05835v2 Announce Type: replace-cross -Abstract: We develop a microscopic theory of magnon-exciton drag effect in a bilayer van der Waals antiferromagnetic semiconductor CrSBr. Effective exciton-magnon coupling arises from an orbital mechanism: Magnons tilt the layer magnetizations, enabling charge carrier tunneling that mixes intra- and interlayer excitons and thereby modulate the exciton energy. We derive the effective Hamiltonian of exciton-magnon coupling, based on our calculation of the magnon spectrum taking into account short-range exchange interaction between Cr-ion spins, single-ion anisotropy, and long-range dipole-dipole interactions. The latter produces a negative group velocity of magnons at small wavevectors. We show that despite rather small renormalization of exciton's energy and effective mass by the exciton-magnon interaction, the three key two-magnon processes: exciton-magnon scattering, two-magnon absorption by exciton, and two-magnon emission are highly efficient. By solving the Boltzmann kinetic equation, we evaluate short exciton-magnon scattering time which is in the sub-ps range and strongly decreases with the increase of magnon population. Hence, exciton-magnon scattering is likely to be dominant over other scattering processes related to the exciton-phonon and exciton-disorder interactions. We demonstrate that magnons can efficiently drag excitons, resulting in a large and nearly isotropic exciton propagation that can significantly exceed the intrinsic anisotropic diffusion. Our results provide a theoretical basis for recent observations of anomalous exciton transport in CrSBr [F. Dirnberger, et al., Nat. Nano. (2025)] and establish magnon-exciton drag as a powerful mechanism for controlling exciton propagation in magnetic systems. - oai:arXiv.org:2512.05835v2 - cond-mat.mes-hall - cond-mat.mtrl-sci + Robust, fast, and efficient formation of stable tetratomic molecules from ultracold atoms via generalized stimulated Raman exact passage + https://arxiv.org/abs/2512.04681 + arXiv:2512.04681v3 Announce Type: replace-cross +Abstract: The study of the conversion of ultracold atoms into molecules has long remained a hot topic in atomic, molecular, and optical physics. However, most prior research has focused on diatomic molecules, with relatively scarce exploration of polyatomic molecules. Here we propose a two-step strategy for the formation of stable ultracold tetratomic molecules. We first suggest a generalized nonlinear stimulated Raman exact passage (STIREP) technique for the coherent conversion of ultracold atoms to tetratomic molecules, which is subsequently followed by a chainwise-STIREP technique to transfer the resulting molecules into a sufficiently stable ground state. Through systematic numerical analysis, we demonstrate that the proposed two-step strategy holds great potential for the robust, fast, and efficient formation of stable ultracold tetratomic molecules. + oai:arXiv.org:2512.04681v3 + cond-mat.quant-gas quant-ph - Tue, 09 Dec 2025 00:00:00 -0500 + Wed, 10 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zakhar A. Iakovlev, Akashdeep Kamra, Mikhail M. Glazov + Jia-Hui Zhang, Wen-Yuan Wang, Fu-Quan Dou