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" @@ -7,1576 +7,1440 @@ http://www.rssboard.org/rss-specification en-us - Wed, 10 Dec 2025 05:00:00 +0000 + Thu, 11 Dec 2025 05:00:00 +0000 rss-help@arxiv.org - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 Saturday Sunday - 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 + An ETH-ansatz-based environmental-branch approach to master equation + https://arxiv.org/abs/2512.09007 + arXiv:2512.09007v1 Announce Type: new +Abstract: In this paper, a method for deriving master equation is developed for a generic small quantum system, which is locally coupled to an environment as a many-body quantum chaotic system that satisfies the eigenstate thermalization hypothesis ansatz, resorting to neither the Born approximation nor the Markov approximation. The total system undergoes Schr\"{o}dinger evolution, under an initial condition in which the environmental branches possess no correlation with the interaction Hamiltonian. Derivation of the master equation is based on piecewise usage of a second-order expansion of a formal expression, which is derived for the evolution of the environmental branches. Approximations used in the derivation are mainly based on dynamic properties of the environment. + oai:arXiv.org:2512.09007v1 quant-ph - cs.AI - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Andrew Kiruluta - - - 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 - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kagwe A. Muchane + Wen-ge Wang - 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 + The Richness of Bell Nonlocality: Generalized Bell Polygamy and Hyper-Polygamy + https://arxiv.org/abs/2512.09034 + arXiv:2512.09034v1 Announce Type: new +Abstract: Non-classical quantum correlations underpin both the foundations of quantum mechanics and modern quantum technologies. Among them, Bell nonlocality is a central example. For bipartite Bell inequalities, nonlocal correlations obey strict monogamy: a violation of one inequality precludes violations of other inequalities on the overlapping subsystems. In the multipartite setting, however, Bell nonlocality becomes inherently polygamous. This was previously shown for subsystems obtained by removing a single particle from an $N$-partite system. Here, we generalize this result to arbitrary $(N-k)$-partite subsystems with $k>0$. We demonstrate that a single $N$-qubit state can violate all $\binom{N}{k}$ relevant Bell inequalities simultaneously. We further construct an $N$-qubit Bell inequality, obtained by symmetrizing the $(N-k)$-qubit ones, that is maximally violated by states exhibiting this generalized polygamy. We compare these violations with those achievable by GHZ states and show that polygamy offers an advantage in multipartite scenarios, providing new insights into scalable certification of non-classicality in quantum devices. Our analysis relies on symmetry properties of the MABK inequalities. Finally, we show that this behavior can occur across multiple subsystem sizes, a phenomenon we call hyper-polygamy. These structures reveal the remarkable abundance of nonlocality present in multipartite quantum states and offer perspectives for their applications in quantum technologies. + oai:arXiv.org:2512.09034v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Shun-Cai Zhao - - - 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 - math-ph - math.MP - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zachary P. Bradshaw, Margarite L. LaBorde, Dillon Montero - - - 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 - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Frank Phillipson - - - 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 - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Jizhi Zhang, Ziang Yang, Zhaoyuan Meng, Zhen Lu, Yue Yang + Gerard Angl\`es Munn\'e, Pawe{\l} Cie\'sli\'nski, Jan W\'ojcik, Wies{\l}aw Laskowski - 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 + Slow dynamics and magnon bound states in the 2D long-range quantum Ising model + https://arxiv.org/abs/2512.09037 + arXiv:2512.09037v1 Announce Type: new +Abstract: The dynamics of long-range quantum Ising models represents a current frontier in experimental physics, notably in trapped ions or Rydberg atomic systems. However, a theoretical description of these dynamics beyond 1D remains a significant challenge for conventional methods. Here, we address this challenge by means of neural quantum states to simulate global quenches from the fully polarized ferromagnetic state in the 2D quantum Ising model with power-law decaying interactions. From these numerically exact simulations, we find that the dynamics exhibit slow relaxation with long-lived oscillations. We explain this behavior through a theory for the formation of magnon bound states, which are generated, as we show, through effective attractive interactions between magnons that persist over several lattice sites due to the power-law nature of the interactions. Our results are readily observable in current quantum simulation platforms realizing long-range interacting models such as in Rydberg atomic systems. + oai:arXiv.org:2512.09037v1 quant-ph - math-ph - math.MP - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.stat-mech + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Shi Jin, Nana Liu + Vighnesh Dattatraya Naik, Markus Heyl - 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 + Optimizing the dynamical preparation of quantum spin lakes on the ruby lattice + https://arxiv.org/abs/2512.09040 + arXiv:2512.09040v1 Announce Type: new +Abstract: Quantum spin liquids are elusive long-range entangled states. Motivated by experiments in Rydberg quantum simulators, recent excitement has centered on the possibility of dynamically preparing a state with quantum spin liquid correlation even when the ground state phase diagram does not exhibit such a topological phase. Understanding the microscopic nature of such quantum spin "lake" states and their relationship to equilibrium spin liquid order remains an essential question. Here, we extend the use of approximately symmetric neural quantum states for real-time evolution and directly simulate the dynamical preparation in systems of up to $N=384$ atoms. We analyze a variety of spin liquid diagnostics as a function of the preparation protocol and optimize the extent of the quantum spin lake thus obtained. In the optimal case, the prepared state shows spin-liquid properties extending over half the system size, with a topological entanglement entropy plateauing close to $\gamma = \ln 2$. We extract two physical length scales $\lambda$ and $\xi$ which constrain the extent of the quantum spin lake $\ell$ from above and below. + oai:arXiv.org:2512.09040v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.dis-nn + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Shreya Kumar, Alex E Jones, Daniel Bhatti, Stefanie Barz + DinhDuy Vu, Dominik S. Kufel, Jack Kemp, Lode Pollet, Chris R. Laumann, Norman Y. Yao - 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 + Quantum bootstrap for central potentials + https://arxiv.org/abs/2512.09041 + arXiv:2512.09041v1 Announce Type: new +Abstract: We study the quantum-mechanical bootstrap as it applies to the bound states of several central potentials in three dimensions. As part of this effort, we show how the bootstrap approach may be applied to ``non-algebraic'' potentials, such as the Yukawa potential (which asymptotically decays as an exponential) and a Gaussian potential. We additionally review the bootstrap of the Coulomb potential, demonstrate a high-precision bootstrap of the Cornell potential, and study conformal quantum mechanics. These results further recommend the bootstrap as a numerical method for high-precision calculations of ground-state physics, where applicable: for example, we are able to determine the critical coupling in the Cornell potential to better than one part in $10^7$, the most precise determination to date. Lower bounds on energies are also of high precision, occasionally one part in greater than $10^8$. Finally, we discuss the circumstances under which we are able to obtain meaningful upper bounds on ground-state energies. + oai:arXiv.org:2512.09041v1 quant-ph - cond-mat.supr-con - Wed, 10 Dec 2025 00:00:00 -0500 + hep-lat + hep-th + Thu, 11 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 + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Scott Lawrence, Brian McPeak - 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 + Dressed-state Hamiltonian engineering in a strongly interacting solid-state spin ensemble + https://arxiv.org/abs/2512.09043 + arXiv:2512.09043v1 Announce Type: new +Abstract: In quantum science applications, ranging from many-body physics to quantum metrology, dipolar interactions in spin ensembles are controlled via Floquet engineering. However, this technique typically reduces the interaction strength between spins, and effectively weakens the coupling to a target sensing field, limiting the metrological sensitivity. In this work, we develop and demonstrate a method for direct tuning of the native interaction in an ensemble of nitrogen-vacancy (NV) centers in diamond. Our approach utilizes dressed-state qubit encoding under a magnetic field perpendicular to the crystal lattice orientation. This method leads to a $3.2\times$ enhancement of the dimensionless coherence parameter $JT_2$ compared to state-of-the-art Floquet engineering, and a $2.6\times$ ($8.3~$dB) enhanced sensitivity in AC magnetometry. Utilizing the extended coherence we experimentally probe spin transport at intermediate to late times. Our results provide a powerful Hamiltonian engineering tool for future studies with NV ensembles and other interacting higher-spin ($S>\frac{1}{2}$) systems. + oai:arXiv.org:2512.09043v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Zhiyi Wu, Xuandong Sun, Songlei Wang, Jiawei Zhang, Xiaohan Yang, Ji Chu, Jingjing Niu, Youpeng Zhong, Xiao Chen, Zhi-Cheng Yang, Dapeng Yu + Haoyang Gao, Nathaniel T. Leitao, Siddharth Dandavate, Lillian B. Hughes Wyatt, Piotr Put, Mathew Mammen, Leigh S. Martin, Hongkun Park, Ania C. Bleszynski Jayich, Mikhail D. Lukin - 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 + Subradiant collective states for precision sensing via transmission spectra + https://arxiv.org/abs/2512.09050 + arXiv:2512.09050v1 Announce Type: new +Abstract: When an ensemble of quantum emitters interacts with a common radiation field, their emission becomes collective, giving rise to superradiant and subradiant states, characterized by broadened and narrowed linewidths. In this work, we propose to harness subradiant states for quantum metrology; such states naturally arise in subwavelength-spaced atomic arrays in free space and in small ensembles of emitters coupled to one-dimensional waveguides. We demonstrate that their collective optical response yields sharp, narrow features in the transmittance spectrum, which can be used to enhance sensitivity to external perturbations. This improved sensitivity can be applied to atomic clock operation, spatially resolved imaging of emitter positions, and enables precise detection of both global and spatially varying detunings (such as those induced by electromagnetic fields or gravitational gradients). + oai:arXiv.org:2512.09050v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.atom-ph + Thu, 11 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Luis D. Zambrano Palma, Yusef Maleki, M. Suhail Zubairy + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Diego Zafra-Bono, Oriol Rubies-Bigorda, Susanne F. Yelin - 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 + Quantum Clocks Tick Faster: Entanglement, Contextuality, and the Flow of Time + https://arxiv.org/abs/2512.09100 + arXiv:2512.09100v1 Announce Type: new +Abstract: Building on the recent proposal that a single ``bona fide'' clock suffices to define spacetime's metric, we introduce an Entangled Clock protocol based on singlet-state correlations. Invoking Zeilinger's Foundational Principle, we argue that while the local flow of time, operationally defined as a sequence of detector ``ticks,'' is irreducibly random (one bit per elementary system), the synchronized flow between spatially separated observers depends on their measurement geometry. Comparing the quantum prediction for the coincidence rate with Peres' classical ``bomb fragment'' model, we find that at obtuse relative angles the entangled clock exhibits a 13 percent higher synchronized tick rate than this linear classical benchmark. This ``temporal acceleration'' is linked to contextuality: following Peres, ``unperformed experiments have no results,'' and quantum systems are not constrained to maintain consistency with all counterfactual measurement settings. We stress, however, that for any single measurement angle a suitably tailored classical model can reproduce the quantum rate. The genuinely nonclassical character of the entangled clock emerges only when correlations at several angles are considered simultaneously and are shown to violate Bell-type inequalities. In this sense, the violation of Bell-type bounds serves as a certification that the shared time standard is genuinely quantum. + oai:arXiv.org:2512.09100v1 quant-ph - math-ph - math.MP - physics.class-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - \'Angel E. Reyna-Cruz, Julio C. Guti\'errez-Vega + Karl Svozil - 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 + Islands of Instability in Nonlinear Wavefunction Models in the Continuum: A Different Route to "Chaos" + https://arxiv.org/abs/2512.09109 + arXiv:2512.09109v1 Announce Type: new +Abstract: In two previous papers the author described ``Islands of Instability" that may appear in wavefunction models with nonlinear evolution (of a type proposed originally in the context of the Measurement Problem). Such ``IsoI" represent a new scenario for Hamiltonian systems implying so-called ``chaos". Criteria was derived for, and shown to be fulfilled in, some finite-dimensional (multi-qubit) models, and generalized in the second paper to continuum models. But the only example produced of the latter was a model whose linear Schrodinger equation was exactly-solvable. As exact solutions of many-body problems are rare, here I show that the instability criteria can be verified by plugging test-functions into certain computable expressions, bypassing the solvability blockade. The method can accommodate realistic inter-molecular potentials and so may be relevant to instabilities in fluids and gasses. + oai:arXiv.org:2512.09109v1 quant-ph - cond-mat.mtrl-sci - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Ethan Decker, Christopher Watson, Junyu Zhou, Yuhao Liu, Chenxu Liu, Ang Li, Gushu Li, Samuel Stein + W. David Wick - 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 + Enhanced Squeezing and Faster Metrology from Layered Quantum Neural Networks + https://arxiv.org/abs/2512.09137 + arXiv:2512.09137v1 Announce Type: new +Abstract: Spin squeezing is a powerful resource for quantum metrology, and recent hardware platforms based on interacting qubits provide multiple possible architectures to generate and reverse squeezing during a sensing protocol. In this work, we compare the sensing performance of three such architectures: quantum reservoir computers (QRCs), quantum perceptrons, and multi-layer quantum neural networks (QNNs), when used as squeezing-based field sensors. For all models, we consider a standard metrological sequence consisting of coherent-spin preparation, one-axis-twisting dynamics, field encoding via a weak rotation, time-reversal, and collective readout. We show that a single quantum perceptron generates the same optimal sensitivity as a QRC, but in the perturbative regime it benefits from accelerated squeezing due to steering by the output qubit. Stacking perceptrons into a QNN further amplifies this effect: in a 2-layer QNN with N_in input and N_out output qubits, the optimal squeezing time is reduced by a factor of N_out, while the achievable phase sensitivity remains Heisenberg-limited, Delta phi ~ 1/(N_in + N_out). Moreover, if the layers are used sequentially, first using the outputs to squeeze the inputs and then the inputs to squeeze the outputs, the two contributions to the response add constructively. This yields a sqrt(2) enhancement in sensitivity over a QRC when N_in = N_out and requires shorter total squeezing time. Generalizing to L layers, we show that the metrological gain scales as sqrt(L) while the required squeezing time decreases as 1/N_l, where N_l is the number of qubits per layer. Our results demonstrate that the structure of quantum neural networks can be exploited not only for computation, but also to engineer faster and more sensitive squeezing-based quantum sensors. + oai:arXiv.org:2512.09137v1 quant-ph - physics.atom-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 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 + Nickholas Gutierrez, Rodrigo Araiza Bravo, Susanne Yelin - 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 + Transition rates and their applications in accelerated single-qubit for fermionic spinor field coupling + https://arxiv.org/abs/2512.09144 + arXiv:2512.09144v1 Announce Type: new +Abstract: In this work, we investigate the interaction between a uniformly accelerated single qubit and a fermionic spinor field. Here we consider both the massless and the massive fermionic spinor fields. The qubit-field interaction occurs over a finite time and was evolved via perturbation theory. This approach yields the transition probability rates, from which we subsequently evaluate the quantum coherence of an Unruh-DeWitt (UDW) detector initially prepared in a qubit state. Our findings reveal that the UDW detector responds more when coupled with the fermionic field, and consequently, quantum coherence (for the fermionic case) degrades much more rapidly when compared to the case of the qubit linearly coupled with the scalar field. Moreover, the analysis suggests that particle mass plays a protective role against Unruh-induced decoherence as the rest mass energy becomes comparable to the detector's energy-level spacing, the detector's excitation probability and response decreases, which leads to the mitigation of quantum coherence degradation in accelerated quantum systems. + oai:arXiv.org:2512.09144v1 quant-ph - cond-mat.mes-hall - cond-mat.mtrl-sci - cond-mat.supr-con - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 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 + Arnab Mukherjee, Sunandan Gangopadhyay, P. H. M. Barros, H. A. S. Costa - 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 + Exact and Efficient Stabilizer Simulation of Thermal-Relaxation Noise for Quantum Error Correction + https://arxiv.org/abs/2512.09189 + arXiv:2512.09189v1 Announce Type: new +Abstract: Stabilizer-based simulation of quantum error-correcting codes typically relies on the Pauli-twirling approximation (PTA) to render non-Clifford noise classically tractable, but PTA can distort the behavior of physically relevant channels such as thermal relaxation. Physically accurate noise simulation is needed to train decoders and understand the noise suppression capabilities of quantum error correction codes. In this work, we develop an exact and stabilizer-compatible model of qubit thermal relaxation noise and show that the combined amplitude damping and dephasing channel admits a fully positive probability decomposition into Clifford operations and reset whenever $T_2 \leqslant T_1$. For $T_2 > T_1$, the resulting decomposition is negative, but allows a smaller sampling overhead versus independent channels. We further introduce an approximated error channel with reset that removes the negativity of the decomposition while achieving higher channel fidelity to the true thermal relaxation than PTA, and extend our construction to finite temperature relaxation. We apply the exact combined model to investigate large surface codes and bivariate bicycle codes on superconducting platforms with realistic thermal relaxation error. The differing logical performances across code states further indicate that noise-model-informed decoders will be essential for accurately capturing thermal-noise structure in future fault-tolerant architectures. + oai:arXiv.org:2512.09189v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - James Fullwood, Boyu Yang + http://creativecommons.org/licenses/by/4.0/ + Sean R. Garner, Nathan M. Myers, Meng Wang, Samuel Stein, Chenxu Liu, Ang Li - 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 + Parallel accelerated electron paramagnetic resonance spectroscopy using diamond sensors + https://arxiv.org/abs/2512.09230 + arXiv:2512.09230v1 Announce Type: new +Abstract: The nitrogen-vacancy (NV) center can serve as a magnetic sensor for electron paramagnetic resonance (EPR) measurements. Benefiting from its atomic size, the diamond chip can integrate a tremendous amount of NV centers to improve the magnetic-field sensitivity. However, EPR spectroscopy using NV ensembles is less efficient due to inhomogeneities in both sensors and targets. Spectral line broadening induced by ensemble averaging is even detrimental to spectroscopy. Here we show a kind of cross-relaxation EPR spectroscopy at zero field, where the sensor is tuned by an amplitude-modulated control field to match the target. The modulation makes detection robust to the sensor's inhomogeneity, while zero-field EPR is naturally robust to the target's inhomogeneity. We demonstrate an efficient EPR measurement on an ensemble of roughly 30000 NV centers. Our method shows the ability to not only acquire unambiguous EPR spectra of free radicals, but also monitor their spectroscopic dynamics in real time. + oai:arXiv.org:2512.09230v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.bio-ph + physics.chem-ph + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alberto J. B. Rosal, Patrick P. Potts, Gabriel T. Landi + 10.1103/PhysRevLett.134.130801 + Phys. Rev. Lett. 134, 130801 (2025) + Zhehua Huang, Zhengze Zhao, Fei Kong, Zhecheng Wang, Pengju Zhao, Xiangtian Gong, Xiangyu Ye, Ya Wang, Fazhan Shi, Jiangfeng Du - 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 + Spontaneous Decoherence from Imaginary-Order Spectral Deformations + https://arxiv.org/abs/2512.09236 + arXiv:2512.09236v1 Announce Type: new +Abstract: We examine a mechanism of spontaneous decoherence in which the generator of quantum dynamics is replaced by the imaginary-order spectral deformation $H^{1+i\beta}$ of a positive Hamiltonian $H$. The deformation modifies dynamical phases through the factor $E^{i\beta} = e^{i\beta \log E}$, whose rapid oscillation suppresses interference between distinct energies. A non-stationary-phase analysis yields quantitative estimates showing that oscillatory contributions to amplitudes or decoherence functionals decay at least as $O(1/|\beta|)$. The Born rule and the Hilbert-space inner product remain unchanged; the modification is entirely dynamical. + The physical motivation for the deformation arises from clock imperfections, renormalization-group and effective-action corrections that introduce logarithmic spectral terms, and semiclassical quantum-gravity analyses in which complex actions produce spectral factors of the form $E^{i\beta}$. Examples including FRW minisuperspace, quartic potentials, curved-background Hamiltonians, and a Schwarzschild interior-type model illustrate how the mechanism yields explicit decoherence rates. The parameter $\beta$ may be experimentally constrained through precision coherence measurements in low-noise quantum platforms. The mechanism contrasts with Milburn-type intrinsic decoherence, Diosi-Penrose gravitational collapse, and real-order fractional dynamics in that it acts purely through deterministic spectral phases of a single Hamiltonian. The analysis positions the framework as a compact and testable phenomenological representation of logarithmic spectral corrections appearing in quantum-gravity-motivated effective theories. + oai:arXiv.org:2512.09236v1 quant-ph gr-qc - Wed, 10 Dec 2025 00:00:00 -0500 - new - 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 - - - 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 - math.CO - Wed, 10 Dec 2025 00:00:00 -0500 + hep-th + math-ph + math.MP + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Alastair Kay, Christino Tamon + Sridhar Tayur - 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 + Harvesting entanglement from the Lorentz-violating quantum field vacuum in a dipolar Bose-Einstein condensate + https://arxiv.org/abs/2512.09263 + arXiv:2512.09263v1 Announce Type: new +Abstract: We theoretically propose an experimentally viable scheme to explore the transfer of nonclassical correlations from a dipolar Bose-Einstein condensate (BEC) to a pair of impurities immersed in it. Operating at ultra-low temperature, density fluctuations of the dipolar BEC emulate a vacuum field with Lorentz-violating dispersion, while the two impurities function as Unruh-DeWitt detectors for the BEC quasiparticles. We study the harvesting of entanglement from the quantum vacuum of this analogue Lorentz-violating quantum field by spatially separated Unruh-DeWitt detectors. Our analysis reveals key parameter dependencies that optimize the harvesting of entanglement. In particular, unlike the Lorentz-invariant case, smoother detector switchings does not enhance the entanglement harvesting efficiency from the Lorentz-violating quantum field vacuum. Moreover, the strength of the Lorentz-invariant violation can shift the optimal energy structure of the detectors for harvesting entanglement from the Lorentz-violating quantum field vacuum-a clear deviation from the Lorentz-invariant scenario. As a fundamental quantum mechanical setup, our quantum fluid platform provides an experimentally realizable testbed for examining the entanglement harvesting protocol from an effective Lorentz-violating quantum field vacuum using a pair of impurity probers, which may also has potential implications for exploring the Lorentz-invariant violation in quantum field theory. + oai:arXiv.org:2512.09263v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + gr-qc + hep-th + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - K. Uriostegui, C. Pineda, C. Chryssomalakos, V. Rasc\'on Barajas, I. V\'azquez Mota + Zehua Tian, Weiping Yao, Xiaobao Liu, Mengjie Wang, Jieci Wang, Jiliang Jing - 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 + Mpemba as an Emergent Effect of System Relaxation + https://arxiv.org/abs/2512.09324 + arXiv:2512.09324v1 Announce Type: new +Abstract: The Mpemba effect (MpE), where a far-from-equilibrium state of a system relaxes faster compared to a state closer to it, is a well-known counterintuitive phenomenon in classical and quantum systems. Various system-specific theories have been proposed to explain this anomalous behavior in driven systems, though the fundamental mechanism of MpE in undriven systems, where MpE was first observed, remains unresolved. This paper provides a generic model of MpE for a quantum system following Markovian relaxation dynamics, regardless of system structure or environment. The key lies in the overlap of initial states with the fast relaxation mode; here, the constituents create a fast decay mode via interaction through the shared environment to show MpE, indicating MpE happens due to the collective behavior of the system. I also show that a system with anisotropic relaxation naturally exhibits MpE, even without a shared environment among the particles. + oai:arXiv.org:2512.09324v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ewout van den Berg, Brad Mitchell, Ken Xuan Wei, Moein Malekakhlagh + Gourab Das - 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 + Routes of Transport in the Path Integral Lindblad Dynamics through State-to-State Analysis + https://arxiv.org/abs/2512.09362 + arXiv:2512.09362v1 Announce Type: new +Abstract: Analyzing routes of transport for open quantum systems with non-equilibrium initial conditions is extremely challenging. The state-to-state approach [A. Bose, and P.L. Walters, J. Chem. Theory Comput. 2023, 19, 15, 4828-4836] has proven to be a useful method for understanding transport mechanisms in quantum systems interacting with dissipative thermal baths, and has been recently extended to non-Hermitian systems to account for empirical loss. These non-Hermitian descriptions are, however, not capable of describing empirical processes of more general nature, including but not limited to a variety of pumping processes. We extend the state-to-state analysis to account for Lindbladian descriptions of generic dissipative, pumping and decohering processes acting on a system which is exchanging energy with a thermal bath. This Lindblad state-to-state method can elucidate routes of transport in systems coupled to a bath and additionally acted upon by Lindblad jump operators. The method is demonstrated using examples of excitonic aggregates subject to incoherent pumping and draining processes. Using this new state-to-state formalism, we demonstrate the establishment of steady-state excitonic currents across molecular aggregates, yielding a different first-principles approach to quantifying the same. + oai:arXiv.org:2512.09362v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.chem-ph + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ozlem Erkilic, Aritra Das, Angela A. Baiju, Nicholas Zaunders, Biveen Shajilal, Timothy C. Ralph + Devansh Sharma, Amartya Bose - 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 + Compact and efficient quantum frequency conversion of a fiber-pigtailed single-photon source + https://arxiv.org/abs/2512.09390 + arXiv:2512.09390v1 Announce Type: new +Abstract: Quantum frequency converters are key enabling technologies in photonic quantum information science to bridge the gap between quantum emitters and telecom photons. Here, we report a co- herent frequency converter scheme combining a fiber-coupled nonlinear optical Lithium Niobate waveguide with a fiber-pigtailed single-photon source based on semiconductor quantum dots. Single and indistinguishable photons are converted from 925.7 nm to the telecommunication C-band, with a 48.4% end-to-end efficiency and full preservation of single-photon purity and indistinguishability. The integration of the two fiber-based modules achieving top-level performance represents an im- portant step toward the practical interconnection of future quantum information processing systems operating at different wavelengths. + oai:arXiv.org:2512.09390v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Mingrui Jing, Mengbo Guo, Lin Zhu, Hongshun Yao, Xin Wang + Mathis Cohen, Anthony Martin, Romain Dalidet, Florian Pastier, Marie Billard, Aristide Lemaitre, Val\'erian Giesz, Niccolo Somaschi, Sarah Thomas, Pascale Senellart-Mardon, S\'ebastien Tanzilli, Laurent Labont\'e - 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 + Two-Photon Bandwidth of Hyper-Entangled Photons in Complex Media + https://arxiv.org/abs/2512.09456 + arXiv:2512.09456v1 Announce Type: new +Abstract: When light propagates through complex media, its output spatial distribution is highly sensitive to its wavelength. This fundamentally limits the bandwidth of applications ranging from imaging to communication. Here, we demonstrate analytically and numerically that the spatial correlations of hyper-entangled photon pairs, simultaneously entangled spatially and spectrally, remain stable across a broad bandwidth: The chromatic modal dispersion experienced by one photon is canceled to first order by its spectrally anti-correlated twin, defining a "two-photon bandwidth" that can far exceed its classical counterpart. We illustrate this modal dispersion cancellation in multimode fibers, thin diffusers and blazed gratings, and demonstrate its utility for broadband wavefront shaping of quantum states. These findings advance our fundamental understanding of quantum light in complex media with applications in quantum imaging, communication, and sensing. + oai:arXiv.org:2512.09456v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.optics + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Pedram Roushan, Leigh S. Martin + Ronen Shekel, Ohad Lib, S\'ebastien M. Popoff, Yaron Bromberg - 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 + LiePrune: Lie Group and Quantum Geometric Dual Representation for One-Shot Structured Pruning of Quantum Neural Networks + https://arxiv.org/abs/2512.09469 + arXiv:2512.09469v1 Announce Type: new +Abstract: Quantum neural networks (QNNs) and parameterized quantum circuits (PQCs) are key building blocks for near-term quantum machine learning. However, their scalability is constrained by excessive parameters, barren plateaus, and hardware limitations. We propose LiePrune, the first mathematically grounded one-shot structured pruning framework for QNNs that leverages Lie group structure and quantum geometric information. Each gate is jointly represented in a Lie group--Lie algebra dual space and a quantum geometric feature space, enabling principled redundancy detection and aggressive compression. Experiments on quantum classification (MNIST, FashionMNIST), quantum generative modeling (Bars-and-Stripes), and quantum chemistry (LiH VQE) show that LiePrune achieves over $10\times$ compression with negligible or even improved task performance, while providing provable guarantees on redundancy detection, functional approximation, and computational complexity. + oai:arXiv.org:2512.09469v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.CV + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Shangyun Wang, Songbai Chen, Jiliang Jing + Haijian Shao, Bowen Yang, Wei Liu, Xing Deng, Yingtao Jiang - 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 + Can Intense Quantum Light Beat Classical Uncertainty Relations? + https://arxiv.org/abs/2512.09558 + arXiv:2512.09558v1 Announce Type: new +Abstract: Uncertainty relations are fundamental to quantum mechanics, encoding limits on the simultaneous measurement of conjugate observables. Violations of joint uncertainty bounds can certify entanglement -- a resource critical for quantum information protocols and increasingly relevant in strong-field physics. Here, we investigate the pairwise time-delay and frequency-bandwidth uncertainties for arbitrary multimode quantum states of light, deriving a general lower bound for their joint product. We find that the nonclassical correction scales inversely with the average photon number, a behavior rooted in the so-called ``monogamy of entanglement''. These results clarify the intensity scaling of quantum advantages in nonclassical light states and highlight the interplay between entanglement and photon statistics. + oai:arXiv.org:2512.09558v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.optics + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Markus Rambach, Abhishek Roy, Alexei Gilchrist, Akitada Sakurai, William J. Munro, Kae Nemoto, Andrew G. White + Felipe Reibnitz Willemann, Mauro Antezza, Johannes Feist - 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 + Exceptional points of arbitrary high orders induced by non-Markovian dynamics + https://arxiv.org/abs/2512.09582 + arXiv:2512.09582v1 Announce Type: new +Abstract: Exceptional points are singularities in the spectrum of non-Hermitian systems in which several eigenvectors are linearly dependent and their eigenvalues are equal to each other. Usually it is assumed that the order of the exceptional point is limited by the number of degrees of freedom of a non-Hermitian system. In this letter, we refute this common opinion and show that non-Markovian effects can lead to dynamics characteristic of systems with exceptional points of higher orders than the number of degrees of freedom in the system. This takes place when the energy returns from reservoir to the system such that the dynamics of the system are divided into intervals in which it describes by the product of the exponential and a polynomial function of ever-increasing order. We demonstrate that by choosing the observation time, it is possible to observe exceptional points of arbitrary high orders. + oai:arXiv.org:2512.09582v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.optics + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Takeaki Miyamura, Zhiling Wang, Kohei Matsuura, Yoshiki Sunada, Keika Sunada, Kenshi Yuki, Jesper Ilves, Yasunobu Nakamura - - - 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 - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - S\"oren Wilkening + Timofey T. Sergeev, Evgeny S. Andrianov, Alexander A. Zyablovsky - 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 + Graph-Based Bayesian Optimization for Quantum Circuit Architecture Search with Uncertainty Calibrated Surrogates + https://arxiv.org/abs/2512.09586 + arXiv:2512.09586v1 Announce Type: new +Abstract: Quantum circuit design is a key bottleneck for practical quantum machine learning on complex, real-world data. We present an automated framework that discovers and refines variational quantum circuits (VQCs) using graph-based Bayesian optimization with a graph neural network (GNN) surrogate. Circuits are represented as graphs and mutated and selected via an expected improvement acquisition function informed by surrogate uncertainty with Monte Carlo dropout. Candidate circuits are evaluated with a hybrid quantum-classical variational classifier on the next generation firewall telemetry and network internet of things (NF-ToN-IoT-V2) cybersecurity dataset, after feature selection and scaling for quantum embedding. We benchmark our pipeline against an MLP-based surrogate, random search, and greedy GNN selection. The GNN-guided optimizer consistently finds circuits with lower complexity and competitive or superior classification accuracy compared to all baselines. Robustness is assessed via a noise study across standard quantum noise channels, including amplitude damping, phase damping, thermal relaxation, depolarizing, and readout bit flip noise. The implementation is fully reproducible, with time benchmarking and export of best found circuits, providing a scalable and interpretable route to automated quantum circuit discovery. + oai:arXiv.org:2512.09586v1 quant-ph - physics.bio-ph - physics.chem-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.AI + cs.LG + cs.NE + cs.NI + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Daniele Loco, Kisa Barkemeyer, Andre R. R. Carvalho, Jean-Philip Piquemal + Prashant Kumar Choudhary, Nouhaila Innan, Muhammad Shafique, Rajeev Singh - 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 + Quantum Gradient Flow Algorithm for Symmetric Positive Definite Systems via Quantum Eigenvalue Transformation: Towards Quantum CAE + https://arxiv.org/abs/2512.09623 + arXiv:2512.09623v1 Announce Type: new +Abstract: In this study, we propose the Quantum Gradient Flow Algorithm (QGFA), a novel quantum algorithm for solving symmetric positive definite (SPD) linear systems based on the variational formulation and time-evolution dynamics. Conventional quantum linear solvers, such as the quantum matrix inverse algorithm (QMIA), focus on approximating the matrix inverse through quantum signal processing (QSP). However, QMIA suffers from a crucial drawback: its computational efficiency deteriorates as the condition number increases. In contrast, classical SPD linear solvers, such as the steepest descent and conjugate gradient methods, are known for their fast convergence, which stems from the variational optimization principle of SPD systems. Inspired by this, we develop QGFA, which obtains the solution vector through the gradient-flow process of the corresponding quadratic energy functional. To validate the proposed method, we apply QGFA to the displacement-based finite element method (FEM) for two-dimensional linear elastic problems under plane stress conditions. The algorithm demonstrates accurate convergence toward classical FEM solutions even with a moderate number of QSP phase factors. Compared with QMIA, QGFA achieves lower relative errors and faster convergence when initialized with suitable initial states, demonstrating its potential as an efficient preconditioned quantum linear solver. The proposed framework provides a physically interpretable connection between classical iterative solvers and quantum computational paradigms. These findings suggest that QGFA can serve as a foundation for future developments in Quantum Computer-Aided Engineering (Quantum CAE), including nonlinear and multiphysics simulations. + oai:arXiv.org:2512.09623v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 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 + Yuto Lewis Terashima, Tadashi Kadowaki, Yohichi Suzuki, Mayu Muramatsu, Katsuhiro Endo - 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 + Geometric Origin of Quantum Entanglement + https://arxiv.org/abs/2512.09640 + arXiv:2512.09640v1 Announce Type: new +Abstract: We investigate massless representations related to the extension of Poincar\`e group constructed in [1]. These representations differ from Wigner's ones of standard Poincar\`e group because the stabilizer of lightlike orbits has extra degrees of freedom. The unitary irreducible representations (UIRs) of massless particles in this extension must decompose as a direct sum of a massless forward (positive zeroth component momentum) and massless backward (negative zeroth component momentum) Wigner's representations linked by internal two valued degree of freedom. We prove that these representations are unitarily equivalent to entangled states of two qubits. This provides a geometric origin of quantum entanglement for photons in the framework of quantum field theory: photons appear as superpositions of backward and forward propagating electromagnetic waves depending on a two valued parameter and this dependency gives rise to correlations between the values of local observables identical to those experienced with an entangled state of two qubits. Finally we describe an experiment capable of distinguishing the two different values of the parameter that links backward and forward massless representations providing experimental falsification of the theory. + oai:arXiv.org:2512.09640v1 quant-ph - math.OA - Wed, 10 Dec 2025 00:00:00 -0500 + hep-th + Thu, 11 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Saptak Bhattacharya + http://creativecommons.org/publicdomain/zero/1.0/ + Marco Zaopo - 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 + Optyx: A ZX-based Python library for networked quantum architectures + https://arxiv.org/abs/2512.09648 + arXiv:2512.09648v1 Announce Type: new +Abstract: Distributed, large-scale quantum computing will need architectures that combine matter-based qubits with photonic links, but today's software stacks target either gate-based chips or linear-optical devices in isolation. We introduce Optyx, an open-source Python framework offering a unified language to program, simulate, and prototype hybrid, networked systems: users create experiments that mix qubit registers, discrete-variable photonic modes, lossy channels, heralded measurements, and real-time feedback; Optyx compiles them via ZX/ZW calculus into optimised tensor-network forms, and executes with state-of-the-art contraction schedulers based on Quimb and Cotengra. Benchmarking on exact multi-photon circuit simulations shows that, versus permanent-based methods, tensor network contraction can deliver speedups of orders of magnitude for low-depth circuits and entangled photon sources, and natively supports loss and distinguishability -- establishing it as both a high-performance simulator and a rapid-prototyping environment for next-generation photonic-network experiments. + oai:arXiv.org:2512.09648v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new - 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 + http://creativecommons.org/licenses/by/4.0/ + Mateusz Kupper, Richie Yeung, Boldizs\'ar Po\'or, Alexis Toumi, William Cashman, Giovanni de Felice - 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 + Entanglement with a mode observable via a tunable interaction with a qubit + https://arxiv.org/abs/2512.09658 + arXiv:2512.09658v1 Announce Type: new +Abstract: We study the possibility of detection of ``spin-boson'' entanglement by qubit only measurements. Such entanglement is impossible to detect by previously proposed schemes that involve a fixed system-environment interaction, because of inherent symmetries within the coupling and the initial state of the environment. We take advantage of the possibility of tuning of qubit-environment coupling, that is available in some qubit realizations. As an example we study a superconducting transmon qubit interacting with a microwave cavity, which is one of such systems and is, furthermore, essential in the context of quantum information processing. We propose suitable Hamiltonian parameters for the preparation and measurement phases of the detection scheme that allow for an experimental test, and verify that the reported signal is nonnegligibly large still at finite temperatures. + oai:arXiv.org:2512.09658v1 quant-ph - math.OC - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zhijian Lai, Dong An, Jiang Hu, Zaiwen Wen + Ma{\l}gorzata Strza{\l}ka, Radim Filip, Katarzyna Roszak - 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 + Pattern Based Quantum Key Distribution using the five qubit perfect code for eavesdropper detection + https://arxiv.org/abs/2512.09672 + arXiv:2512.09672v1 Announce Type: new +Abstract: I propose a new quantum key distribution protocol that uses the five qubit error correction code to detect the presence of eavesdropper reliably. The protocol turns any information theoretical attacks into a classical guess about the pattern. The logical qubit is encoded with a specific pattern into a block of five physical qubits. The security of the protocol relies on the correct pattern choice of Alice and Bob. Decoding with any wrong pattern choice increases multi qubit error rate and the 5 qubit code transforms an eavesdropper's logical disturbance into a signature that is detectable and distinguishable from natural channel noise up to a certain distance. + oai:arXiv.org:2512.09672v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 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 + Mehedi Hasan Rumi - 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 + Three-body interaction in a magnon-Andreev-superconducting qubit system: collapse-revival phenomena and entanglement redistribution + https://arxiv.org/abs/2512.09697 + arXiv:2512.09697v1 Announce Type: new +Abstract: Three-body interactions are fundamental for realizing novel quantum phenomena beyond pairwise physics, yet their implementation -- particularly among distinct quantum systems -- remains challenging. Here, we propose a hybrid quantum architecture comprising a magnonic mode (in a YIG sphere), an Andreev spin qubit (ASQ), and a superconducting qubit (SCQ), to realize a strong three-body interaction at the single-quantum level. Leveraging the spin-dependent supercurrent and circuit-integration flexibility of the ASQ, it is possible to engineer a strong tripartite coupling that jointly excites both qubits upon magnon annihilation (or excites magnons and SCQs upon ASQ deexcitation). Through analytical and numerical studies, we demonstrate that this interaction induces synchronized collapse and revival in qubit populations when the magnon is initially prepared in a coherent state. Notably, during the collapse region -- where populations remain static -- the entanglement structure undergoes a dramatic and continuous reorganization. We show that the genuine tripartite entanglement is redistributed into bipartite entanglement between the two qubits, and vice versa, with the total entanglement conserved. These phenomena, unattainable via two-body couplings, underscore the potential of three-body interactions for exploring intrinsically new quantum effects and advancing hybrid quantum information platforms. + oai:arXiv.org:2512.09697v1 quant-ph - physics.acc-ph - physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 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 + Sheng Zhao, Peng-Bo Li - 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 + Device Independent Quantum Secret Sharing Using Multiparty Pseudo-telepathy Game + https://arxiv.org/abs/2512.09699 + arXiv:2512.09699v1 Announce Type: new +Abstract: Device-independent quantum secret sharing (DI-QSS) is a cryptographic protocol that overcomes the security limitations posed by untrusted quantum devices. We propose a DI-QSS protocol based on the multipartite pseudo-telepathy parity game, which achieves device-independence with simultaneous key generation without requiring dedicated test rounds, unlike CHSH-based schemes [Zhang et al., Phys. Rev. A, 2024]. Notably, the proposed scheme allows simultaneous device-independence verification and key-generation phases, achieving optimal performance for a seven-qubit GHZ state configuration. Further, we analyse the security of our protocol against collective attack and establish reduced resource requirement for the same length of the raw key compared to the previous protocol. Finally, we show that our protocol remains robust even in a noisy environment. + oai:arXiv.org:2512.09699v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.CR + Thu, 11 Dec 2025 00:00:00 -0500 new 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 + Santanu Majhi, Goutam Paul - 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 + Dynamic stimulated emission for deterministic addition and subtraction of propagating photons + https://arxiv.org/abs/2512.09711 + arXiv:2512.09711v1 Announce Type: new +Abstract: Photon subtraction and addition are essential non-Gaussian processes in quantum optics, where conventional methods using linear optics and number-resolving detection often suffer from low success probability. Here, we introduce the concept of \textit{dynamic stimulated emission}, whereby a quantum emitter undergoes stimulated emission with a time-dependent coupling. We show that, for both two- and three-level emitters, this process can be used to deterministically add or subtract a photon to a single propagating optical mode. We provide semi-analytic solutions to this problem for Fock states, enabling deterministic and unconditional single-photon subtraction and addition with fidelity ${\cal F}>0.996$. Our semi-analytic solutions are provided for both dynamically coupled two-level systems and for three-level systems whose dynamical coupling is controlled by a coherent laser drive. Moving beyond individual Fock states, we further showcase the ability to subtract and add single photons to photon-number superposition states. We show that Schr\"{o}dinger cat states can be prepared from squeezed vacuum input via cascaded subtraction or cascaded addition. Finally, we show that our photon-addition process can be used to add a photon to any squeezed and displaced state with high success probability and fidelity ${\cal F}>0.99$, thereby potentially converting quantum emitters from single-photon sources to sources of single-photon-added Gaussian states without the need for inline squeezing. Our protocols provide a path towards integrating quantum emitters to construct efficient sources of single-mode non-Gaussian light beyond single photons. + oai:arXiv.org:2512.09711v1 quant-ph - cond-mat.mes-hall - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 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 + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Haoyuan Luo, Parth S. Shah, Frank Yang, Mohammad Mirhosseini, Sahand Mahmoodian - 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 + Quantum random number generation from the continuous variable payload for the SPOQC mission + https://arxiv.org/abs/2512.09716 + arXiv:2512.09716v1 Announce Type: new +Abstract: The necessity of random numbers for various tasks, from simulation to cryptography, is crucial and immense. Here we demonstrate CV-QRNG using the CV payload of the SPOQC mission. The homodyne setup for QRNG uses the laser from the payload, in addition to potentially being used as detector in the case of an uplink scenario. Here we quantify the extractable secure randomness from the QRNG setup, that involves homodyne measurement of the vacuum states. The extracted randomness is tested against NIST test suite in addition to formally upper bounding the min-entropy. With the raw key length being $\approx1$ Mb in a given satellite pass, we get a total length of $\approx19.5$ Kb of certified random numbers from the 12-bit ADC. + oai:arXiv.org:2512.09716v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kentaro Imafuku + http://creativecommons.org/licenses/by/4.0/ + Vinod N. Rao, Killian Murphy, Fadi Ahwal, Emma Tien Hwai Medlock, Timothy P. Spiller, Rupesh Kumar - 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 + Quantumness certification via non-demolition measurements + https://arxiv.org/abs/2512.09734 + arXiv:2512.09734v1 Announce Type: new +Abstract: The fundamental question of when a static or dynamic system should be deemed intrinsically quantum remains a challenge to address in absolute terms. A rigorous criterion, however, can be established by focusing on the measurable or reconstructible features of the system. This determination transcends mere issues of a system's classical simulability or computational complexity. Instead, the critical requirement lies in the certification (ideally, in real-time) of the emergence and persistence of genuine quantum features, principally entanglement and quantum superposition. Quantum Non-Demolition Measurements (QNDM) serve as the appropriate instrument for this certification, both from a theoretical and experimental standpoint. In this review paper, we demonstrate, with accessible clarity, how the implementation of QNDM can be directly linked to a necessary and sufficient condition for the violation of macrorealism in finite-dimensional systems, establishing a conceptual parallel with Leggett-Garg inequalities. Using concrete examples that detail the detection of negative terms in the quasi-probability density function resulting from QNDM, we introduce the core concepts for certifying genuinely quantum features. As specific examples, we discuss an application where the quantum-to-classical transition due to the interaction with an environment can be tracked by QNDM. Moreover, we argue about the robustness of QNDM protocols in the presence of noise sources and their advantages with respect to the Leggett-Garg inequalities. Because of its straightforward implementation, the QNDM approach can be of direct relevance to both the foundations of quantum mechanics and quantum information theory, where a controlled generation and certification of genuinely quantum resources is a central concern. + oai:arXiv.org:2512.09734v1 quant-ph - physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Niels Tripier-Mondancin, David Barral, Gana\"el Roeland, Ra\'ul Leonardo Rincon Celis, Yann Bouchereau, Nicolas Treps + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Paolo Solinas, Stefano Gherardini - 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 + Quantum error correction via purification using a single auxiliary + https://arxiv.org/abs/2512.09745 + arXiv:2512.09745v1 Announce Type: new +Abstract: We propose a single auxiliary-assisted purification-based framework for quantum error correction, capable of correcting errors that drive a system from its ground-state subspace into excited-state sectors. The protocol consists of a joint time evolution of the system-auxiliary duo under a specially engineered interaction Hamiltonian, followed by a single measurement of the auxiliary in its energy eigenbasis and a subsequent post-selection of one of the measurement outcomes. We show that the resulting purified state always achieves unit fidelity, while the probability of obtaining any energy of the auxiliary other than its ground state energy yields the success rate of the protocol. We demonstrate the power of this proposed method for several low-distance quantum codes, including the three-, four-, and five-qubit codes, and for the one-dimensional isotropic Heisenberg model, subjected to bit-flip, phase-flip, and amplitude-damping noises acting on all qubits. Notably, the protocol expands the class of correctable errors for a given code, particularly in the presence of amplitude-damping noise. We further analyze the impact of replacing the auxiliary qudit with a single auxiliary qubit, and the changes in the performance of the protocol under the realistic scenario where noise remains active during the correction cycle. + oai:arXiv.org:2512.09745v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.str-el + Thu, 11 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - D. -S. Wang, X. Xu, Y. -D. Liu + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Chandrima B. Pushpan, Tanoy Kanti Konar, Aditi Sen De, Amit Kumar Pal - $\mathcal{PT}$-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 + Rotational excitation of molecules in the regime of strong ro-vibrational coupling: Comparison between an optical centrifuge and a transform-limited pulse + https://arxiv.org/abs/2512.09746 + arXiv:2512.09746v1 Announce Type: new +Abstract: We investigate theoretically the ability of an optical centrifuge - a laser pulse whose linear polarization is rotating at an accelerated rate, to control molecular rotation in the regime when the rigid-rotor approximation breaks down due to coupling between the vibrational and rotational degrees of freedom. Our analysis demonstrates that the centrifuge field enables controlled excitation of high rotational states while maintaining relatively low spread along the vibrational coordinate. We contrast this to the rotational excitation by a linearly polarized Gaussian pulse of equal spectral width and pulse energy which, although comparable to the centrifuge-induced rotation, is unavoidably accompanied by a substantial broadening of the vibrational wavepacket. + oai:arXiv.org:2512.09746v1 quant-ph - math-ph - math.MP - physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 + physics.atom-ph + physics.chem-ph + physics.comp-ph + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Cham Oumie, Wu-Ming Liu, Kashif Ammar Yasir + J. M. Garc\'ia-Garrido, V. Milner, C. P. Koch, R. Gonz\'alez-F\'erez - 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 + Optimal certification of constant-local Hamiltonians + https://arxiv.org/abs/2512.09778 + arXiv:2512.09778v1 Announce Type: new +Abstract: We study the problem of certifying local Hamiltonians from real-time access to their dynamics. Given oracle access to $e^{-itH}$ for an unknown $k$-local Hamiltonian $H$ and a fully specified target Hamiltonian $H_0$, the goal is to decide whether $H$ is exactly equal to $H_0$ or differs from $H_0$ by at least $\varepsilon$ in normalized Frobenius norm, while minimizing the total evolution time. We introduce the first intolerant Hamiltonian certification protocol that achieves optimal performance for all constant-locality Hamiltonians. For general $n$-qubit, $k$-local, traceless Hamiltonians, our procedure uses $O(c^k/\varepsilon)$ total evolution time for a universal constant $c$, and succeeds with high probability. In particular, for $O(1)$-local Hamiltonians, the total evolution time becomes $\Theta(1/\varepsilon)$, matching the known $\Omega(1/\varepsilon)$ lower bounds and achieving the gold-standard Heisenberg-limit scaling. Prior certification methods either relied on implementing inverse evolution of $H$, required controlled access to $e^{-itH}$, or achieved near-optimal guarantees only in restricted settings such as the Ising case ($k=2$). In contrast, our algorithm requires neither inverse evolution nor controlled operations: it uses only forward real-time dynamics and achieves optimal intolerant certification for all constant-locality Hamiltonians. + oai:arXiv.org:2512.09778v1 quant-ph - cs.CR - Wed, 10 Dec 2025 00:00:00 -0500 + cs.CC + cs.DS + cs.IT + cs.LG + math.IT + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1109/LCOMM.2025.3625640 - Esther H\"anggi, Iy\'an M\'endez Veiga, Ligong Wang + Junseo Lee, Myeongjin Shin - 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 + Pinball: A Cryogenic Predecoder for Quantum Error Correction Decoding Under Circuit-Level Noise + https://arxiv.org/abs/2512.09807 + arXiv:2512.09807v1 Announce Type: new +Abstract: Scaling fault tolerant quantum computers, especially cryogenic systems, to millions of qubits is challenging due to poorly-scaling data processing and power consumption overheads. One key challenge is the design of decoders for real-time quantum error correction (QEC), which demands high data rates for error processing; this is particularly apparent in systems with cryogenic qubits and room temperature (RT) decoders. In response, cryogenic predecoding using lightweight logic has been proposed to handle common, sparse errors in the cryogenic domain. However, prior work only accounts for a subset of error sources present in real-world quantum systems with limited accuracy, often degrading performance below a useful level in practical scenarios. Furthermore, prior reliance on SFQ logic precludes detailed architecture-technology co-optimization. + To address these shortcomings, this paper introduces Pinball, a comprehensive design in cryogenic CMOS of a QEC predecoder tailored to realistic, circuit-level noise. By accounting for error generation and propagation through QEC circuits, our design achieves higher predecoding accuracy, outperforming logical error rates (LER) of the current state-of-the-art cryogenic predecoder by nearly six orders of magnitude. Remarkably, despite operating under much stricter power and area constraints, Pinball also reduces LER by 32.58x and 5x, respectively, compared to the state-of-the-art RT predecoder and RT ensemble configurations. By increasing cryogenic coverage, we also reduce syndrome bandwidth up to 3780.72x. Through co-design with 4 K-characterized 22 nm FDSOI technology, we achieve a peak power consumption under 0.56 mW. Voltage/frequency scaling and body biasing enable 22.2x lower typical power consumption, yielding up to 67.4x total energy savings. Assuming a 4 K power budget of 1.5 W, our predecoder supports up to 2,668 logical qubits at d=21. + oai:arXiv.org:2512.09807v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.AR + cs.ET + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zixuan Liu, Ognyan Oreshkov + Alexander Knapen, Guanchen Tao, Jacob Mack, Tomas Bruno, Mehdi Saligane, Dennis Sylvester, Qirui Zhang, Gokul Subramanian Ravi - 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 + Quantum Algorithm for Estimating Ollivier-Ricci Curvature + https://arxiv.org/abs/2512.09822 + arXiv:2512.09822v1 Announce Type: new +Abstract: We introduce a quantum algorithm for computing the Ollivier Ricci curvature, a discrete analogue of the Ricci curvature defined via optimal transport on graphs and general metric spaces. This curvature has seen applications ranging from signaling fragility in financial networks to serving as basic quantities in combinatorial quantum gravity. For inputs given as a point cloud with pairwise distances, we show that our algorithm can achieve an exponential speedup over the best-known classical methods for two particular classes of problem. Our work is another step toward quantum algorithms for geometrical problems that are capable of delivering practical value while also informing fundamental theory. + oai:arXiv.org:2512.09822v1 quant-ph - physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 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 + Nhat A. Nghiem, Linh Nguyen, Tuan K. Do, Tzu-Chieh Wei, Trung V. Phan - 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 + Transpiling quantum circuits by a transformers-based algorithm + https://arxiv.org/abs/2512.09834 + arXiv:2512.09834v1 Announce Type: new +Abstract: Transformers have gained popularity in machine learning due to their application in the field of natural language processing. They manipulate and process text efficiently, capturing long-range dependencies among data and performing the next word prediction. On the other hand, gate-based quantum computing is based on controlling the register of qubits in the quantum hardware by applying a sequence of gates, a process which can be interpreted as a low level text programming language. We develop a transformer model capable of transpiling quantum circuits from the qasm standard to other sets of gates native suited for a specific target quantum hardware, in our case the set for the trapped-ion quantum computers of IonQ. The feasibility of a translation up to five qubits is demonstrated with a percentage of correctly transpiled target circuits equal or superior to 99.98%. Regardless the depth of the register and the number of gates applied, we prove that the complexity of the transformer model scales, in the worst case scenario, with a polynomial trend by increasing the depth of the register and the length of the circuit, allowing models with a higher number of parameters to be efficiently trained on HPC infrastructures. + oai:arXiv.org:2512.09834v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Dmitriy Kondaurov, Evgeny Polyakov + Michele Banfi, Paolo Zentilini, Sebastiano Corli, Enrico Prati - 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 + Practical and Efficient Verification of Entanglement with Incomplete Measurement Settings + https://arxiv.org/abs/2512.09856 + arXiv:2512.09856v1 Announce Type: new +Abstract: In this work, we present a practical and efficient framework for verifying entangled states when only a tomographically incomplete measurement setting is available-specifically, when access to observables is severely limited. We show how the experimental estimation of a small number of observables can be directly exploited to construct a large family of entanglement witnesses, enabling the efficient identification of entangled states. Moreover, we introduce an optimization approach, formulated as a semidefinite program, that systematically searches for those witnesses best suited to reveal entanglement under the given measurement constraints. We demonstrate the practicality of the approach in a proof-of-principle experiment with photon-polarization qubits, where entanglement is certified using only a fraction of the full measurement data. These results reveal the maximal usefulness of incomplete measurement settings for entanglement verification in realistic scenarios. + oai:arXiv.org:2512.09856v1 quant-ph physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kangkang Li, Yue Wang, Ze Wang, Xin Zhou, Jincheng Li, Yinke Cheng, Binyan Wu, Qihuang Gong, Bei-Bei Li, Qi-Fan Yang - - - 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 - cond-mat.quant-gas - physics.app-ph - physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Kashif Ammar Yasir, Gao Xianlong + Jiheon Seong, Jin-Woo Kim, Seungchan Seo, Seung-Hyun Nam, Anindita Bera, Dariusz Chru\'sci\'nski, June-Koo Kevin Rhee, Heonoh Kim, Joonwoo Bae - 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 + True Random Number Generators on IQM Spark + https://arxiv.org/abs/2512.09862 + arXiv:2512.09862v1 Announce Type: new +Abstract: Random number generation is fundamental for many modern applications including cryptography, simulations and machine learning. Traditional pseudo-random numbers may offer statistical unpredictability, but are ultimately deterministic. On the other hand, True Random Number Generation (TRNG) offers true randomness. One way of obtaining such randomness are quantum systems, including quantum computers. As such the use of quantum computers for TRNG has received considerable attention in recent years. However, existing studies almost exclusively consider IBM quantum computers, often stop at using simulations and usually test only a handful of different TRNG quantum circuits. In this paper, we address those issues by presenting a study of TRNG circuits on Odra 5 a real-life quantum computer installed at Wroc{\l}aw University of Science and Technology. It is also the first study to utilize the IQM superconducting architecture. Since Odra 5 is available on-premises it allows for much more comprehensive study of various TRNG circuits. In particular, we consider 5 types of TRNG circuits with 105 circuit subvariants in total. Each circuit is used to generate 1 million bits. We then perform an analysis of the quality of the obtained random sequences using the NIST SP 800-22 and NIST SP 800-90B test suites. We also provide a comprehensive review of existing literature on quantum computer-based TRNGs. + oai:arXiv.org:2512.09862v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.CR + Thu, 11 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Chengzhuo Xu, Xiao Chen, Xi Li, Zhihao Liu, Zhigang Li + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Andrzej Gnatowski, Jaros{\l}aw Rudy, Teodor Ni\.zy\'nski, Krzysztof \'Swi\k{e}cicki - 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 + Error Mitigation of Fault-Tolerant Quantum Circuits with Soft Information + https://arxiv.org/abs/2512.09863 + arXiv:2512.09863v1 Announce Type: new +Abstract: Quantum error mitigation (QEM) is typically viewed as a suite of practical techniques for today's noisy intermediate-scale quantum devices, with limited relevance once fault-tolerant quantum computers become available. In this work, we challenge this conventional wisdom by showing that QEM can continue to provide substantial benefits in the era of quantum error correction (QEC), and in an even more efficient manner than it does on current devices. We introduce a framework for logical-level QEM that leverages soft information naturally produced by QEC decoders, requiring no additional data, hardware modifications, or runtime overhead beyond what QEC protocols already provide. Within this framework, we develop and analyze three logical-level QEM techniques: post-selection and runtime abort policies, probabilistic error cancellation, and zero-noise extrapolation. Our techniques reduce logical error rates by more than 100x while discarding fewer than 0.1% of shots; they also provide in situ characterization of logical channels for QEM protocols. As a proof of principle, we benchmark our approach using a surface-code architecture and two state-of-the-art decoders based on tensor-network contraction and minimum-weight perfect matching. We evaluate logical-level QEM on random Clifford circuits and molecular simulation algorithms and find that, compared to previous approaches relying on QEC only or QEC combined with QEM, we can achieve up to 87.4% spacetime overhead savings. Our results demonstrate that logical-level QEM with QEC decoder soft information can reliably improve logical performance, underscoring the efficiency and usefulness of QEM techniques for fault-tolerant quantum computers. + oai:arXiv.org:2512.09863v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tian-Yi Gu, Gaoyong Sun + http://creativecommons.org/licenses/by/4.0/ + Zeyuan Zhou, Shaun Pexton, Aleksander Kubica, Yongshan Ding - 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 + Tomographic characterization of non-Hermitian Hamiltonians in reciprocal space + https://arxiv.org/abs/2512.09870 + arXiv:2512.09870v1 Announce Type: new +Abstract: Non-Hermitian Hamiltonians enrich quantum physics by extending conventional phase diagrams, enabling novel topological phenomena, and realizing exceptional points with potential applications in quantum sensing. Here, we present an experimental photonic platform capable of simulating a non-unitary quantum walk generated by a peculiar type of non-Hermitian Hamiltonian, largely unexplored in the literature. The novelty of this platform lies in its direct access to the reciprocal space, which enables us to scan the quasi-momentum across the entire Brillouin zone and thus achieve a precise tomographic reconstruction of the underlying non-Hermitian Hamiltonian, indicated by the comparison between theoretical predictions and experimental measurements. From the inferred Hamiltonian, it is possible to retrieve complex-valued band structures, resolve exceptional points in momentum space, and detect the associated parity-time symmetry breaking through eigenvector coalescence. Our results, presented entirely in quasi-momentum space, represent a substantial shift in perspective in the study of non-Hermitian phenomena. + oai:arXiv.org:2512.09870v1 quant-ph - cond-mat.quant-gas - cond-mat.stat-mech - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alex Gunning, Aydin Deger, Sridevi Kuriyattil, Andrew J. Daley + Francesco Di Colandrea, Fabrizio Pavan, Sarvesh Bansal, Paola Savarese, Grazia Di Bello, Giulio De Filippis, Carmine Antonio Perroni, Donato Farina, Filippo Cardano - 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 + A 0.8395-approximation algorithm for the EPR problem + https://arxiv.org/abs/2512.09896 + arXiv:2512.09896v1 Announce Type: new +Abstract: We give an efficient 0.8395-approximation algorithm for the EPR Hamiltonian. Our improvement comes from a new nonlinear monogamy-of-entanglement bound on star graphs and a refined parameterization of a shallow quantum circuit from previous works. We also prove limitations showing that current methods cannot achieve substantially better approximation ratios, indicating that further progress will require fundamentally new techniques. + oai:arXiv.org:2512.09896v1 quant-ph - cond-mat.str-el - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - David Blanik, Jos\'e Garre-Rubio - - - 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 - cond-mat.mes-hall - Wed, 10 Dec 2025 00:00:00 -0500 + cs.DS + Thu, 11 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Adrian Parra-Rodriguez, Miguel Clavero-Rubio, Philippe Gigon, Tom\'as Ramos, \'Alvaro G\'omez-Le\'on, Diego Porras + Anuj Apte, Eunou Lee, Kunal Marwaha, Ojas Parekh, Lennart Sinjorgo, James Sud - 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 + Two simple models derived from a quantum-mechanical particle on an elliptical path + https://arxiv.org/abs/2512.09905 + arXiv:2512.09905v1 Announce Type: new +Abstract: We analyze two simple models derived from a quantum-mechanical particle on an elliptical path. The first Hamiltonian operator is non-Hermitian but isomorphic to an Hermitian operator. It appears to exhibit the same two-fold degeneracy as the particle on a circular path. More precisely, $E_n=n^2E_1,\ n=1,2,\ldots$ (in addition to an exact eigenvalue $E_0=0$). The second Hamiltonian operator is Hermitian and does not exhibit such degeneracy. In this case the nth excited energy level splits at the nth order of perturbation theory. Both models can be described in terms of the same point-group symmetry. + oai:arXiv.org:2512.09905v1 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jalan A. Ziyad, Robin Blume-Kohout, Kenneth Rudinger + Francisco M. Fern\'andez - 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 - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Pablo Tikas Pueyo, Tom\'as Fern\'andez Martos, Gabriel Senno - - - 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 + A Hierarchy of Entanglement Cones via Rank-Constrained $C^*$-Convex Hulls + https://arxiv.org/abs/2512.05560 + arXiv:2512.05560v1 Announce Type: cross +Abstract: This paper systematically investigates the geometry of fundamental quantum cones, the separable cone ($\mathscr{P}_+$) and the Positive Partial Transpose (PPT) cone ($\mathcal{P}_{\mathrm{PPT}}$), under generalized non-commutative convexity. We demonstrate a sharp stability dichotomy analyzing $C^*$-convex hulls of these cones: while $\mathscr{P}_+$ remains stable under local $C^*$-convex combinations, its global $C^*$-convex hull collapses entirely to the cone of all positive semidefinite matrices, $\operatorname{MCL}(\mathscr{P}_+) = \mathscr{P}_0$. To gain finer control and classify intermediate structures, we introduce the concept of ``$k$-$C^*$-convexity'', by using the operator Schmidt rank of $C^*$-coefficients. This constraint defines a new hierarchy of nested intermediate cones, $\operatorname{MCL}_k(\cdot)$. We prove that this hierarchy precisely recovers the known Schmidt number cones for the separable case, establishing a generalized convexity characterization: $\operatorname{MCL}_k(\mathscr{P}_+) = \mathcal{T}_k$. Applied to the PPT cone, this framework generates a family of conjectured non-trivial intermediate cones, $\mathcal{C}_{\mathrm{PPT}, k}$. + oai:arXiv.org:2512.05560v1 + math-ph + math.FA + math.MP quant-ph - cs.AI - Wed, 10 Dec 2025 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - David Zenati, Eliya Nachmani + Thu, 11 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Mohsen Kian - 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 + Internal spaces of fermion and boson fields, described with the superposition of odd and even products of $\gamma^{a}$, enable understanding of all the second-quantised fields in an equivalent way + https://arxiv.org/abs/2512.09008 + arXiv:2512.09008v1 Announce Type: cross +Abstract: Using the odd and even ``basis vectors'', which are the superposition of odd and even products of $\gamma^a$'s, to describe the internal spaces of the second quantised fermion and boson fields, respectively, offers in even-dimensional spaces, like it is $d=(13+1)$, the unique description of all the properties of the observed fermion fields (quarks and leptons and antiquarks and antileptons appearing in families) and boson fields (gravitons, photons, weak bosons, gluons and scalars) in a unique way, providing that all the fields have non zero momenta only in $d =(3+1)$ of the ordinary space-time, bosons have the space index $\alpha$ (which is for tensors and vectors $\mu =(0,1,2,3)$ and for scalars $\sigma \ge 5$). In any even-dimensional space, there is the same number of internal states of fermions appearing in families and their Hermitian conjugate partners as it is of the two orthogonal groups of boson fields having the Hermitian conjugate partners within the same group. A simple action for massless fermion and boson fields describes all the fields uniquely. The paper overviews the theory, presents new achievements and discusses the open problems of this theory. + oai:arXiv.org:2512.09008v1 + hep-th quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 - new + Thu, 11 Dec 2025 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - Tharon D. Morrison, Joonhyuk Kwon, Matthew A. Delaney, David R. Leibrandt, Daniel Stick, Hayden J. McGuinness + N. S. Manko\v{c} Bor\v{s}tnik - 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 + Swimming against a superfluid flow: Self-propulsion via vortex-antivortex shedding in a quantum fluid of light + https://arxiv.org/abs/2512.09028 + arXiv:2512.09028v1 Announce Type: cross +Abstract: A superfluid flows without friction below a critical velocity, exhibiting zero drag force on impurities. Above this threshold, superfluidity breaks down, and the internal energy is redistributed into incoherent excitations such as vortices. We demonstrate that a finite-mass, mobile impurity immersed in a flowing two-dimensional paraxial superfluid of light can \textit{swim} against the superfluid current when this critical velocity is exceeded. This self-propulsion is achieved by the periodic emission of quantized vortex-antivortex pairs downstream, which impart an upstream recoil momentum that results in a net propulsive force. Analogous to biological systems that minimize effort by exploiting wake turbulence, the impurity harnesses this vortex backreaction as a passive mechanism of locomotion. Reducing the impurity dynamics to the motion of its center of mass and using a point-vortex model, we quantitatively describe how this mechanism depends on the impurity geometry and the surrounding flow velocity. Our findings establish a fundamental link between internal-energy dissipation in quantum fluids and concepts of self-propulsion in active-matter systems, and opens new possibilities for exploiting vortices for controlled quantum transport at the microscale. + oai:arXiv.org:2512.09028v1 cond-mat.quant-gas - physics.flu-dyn + cond-mat.soft quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Myrann Baker-Rasooli, Nathan du Toit, Nicolas Pavloff, Quentin Glorieux + Myrann Baker-Rasooli, Tangui Aladjidi, Tiago D. Ferreira, Alberto Bramati, Mathias Albert, Pierre-\'Elie Larr\'e, Quentin Glorieux - 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 + Extreme statistics as a probe of the superfluid to Bose-glass Berezinskii-Kosterlitz-Thouless transition + https://arxiv.org/abs/2512.09029 + arXiv:2512.09029v1 Announce Type: cross +Abstract: Recent studies of delocalization-localization transitions in disordered quantum chains have highlighted the role of rare, chain-breaking events that favor localization, in particular for high-energy eigenstates related to many-body localization. In this context, we revisit the random-field XXZ spin-1/2 chain at zero temperature with ferromagnetic interactions, equivalent to interacting fermions or hard-core bosons in a random potential with attractive interactions. We argue that localization in this model can be characterized by chain-breaking events, which are probed by the extreme values of simple local observables, such as the on-site density or the local magnetization, that are readily accessible in both experiments and numerical simulations. Adopting a bosonic language, we study the disorder-induced Berezinskii-Kosterlitz-Thouless (BKT) quantum phase transition from superfluid (SF) to Bose glass (BG), and focus on the strong disorder regime where localization is driven by weak links. Based on high-precision density matrix renormalization group simulations, we numerically show that extreme local densities accurately capture the BKT transition, even for relatively short chains ranging from a few dozen to a hundred sites. We also discuss the SF-BG transition in the weak disorder regime, where finite-size effects pose greater challenges. Overall, our work seeks to establish a solid foundation for using extreme statistics of local observables, such as density, to probe delocalization-localization transitions in disordered quantum chains, both in the ground state and at high energy. + oai:arXiv.org:2512.09029v1 + cond-mat.dis-nn + cond-mat.quant-gas + cond-mat.str-el quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sebasti\'an Franchino-Vi\~nas, J\'er\'emie Quevillon, Diego Saviot + http://creativecommons.org/licenses/by/4.0/ + Jeanne Colbois, Natalia Chepiga, Shaffique Adam, Gabriel Lemari\'e, Nicolas Laflorencie - 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 + Beyond Ginibre statistics in open Floquet chaotic systems with localized leaks + https://arxiv.org/abs/2512.09038 + arXiv:2512.09038v1 Announce Type: cross +Abstract: We show that the spectral properties of driven quantum systems with a classically chaotic counterpart and spatially localized openness, such as optical or microwave billiards with leaks, deviate from predictions of Ginibre ensembles. Our analysis focuses on the leaky quantum standard map (QSM) of the kicked rotor. We compare its complex resonance spectrum with both Ginibre and truncated circular orthogonal ensembles (TCOEs). We find that the long-lived resonances follow TCOE statistics, reproducing the density of states and level spacing correlations, but depart from Ginibre predictions. Short-lived resonances, however, do not show a clear correspondence with either random-matrix ensemble. We also demonstrate that increasing the leak size takes the density of states of the TCOE toward the Ginibre limit, yet their spectral correlations remain distinct. + oai:arXiv.org:2512.09038v1 cond-mat.stat-mech - cond-mat.str-el quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross - http://creativecommons.org/licenses/by/4.0/ - Christian Northe, Paolo Rossi + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Edson M. Signor, Miguel A. Prado Reynoso, Bidhi Vijaywargia, Sandra D. Prado, Lea F. Santos - 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 + On modeling quantum point contacts in quantum Hall systems + https://arxiv.org/abs/2512.09045 + arXiv:2512.09045v1 Announce Type: cross +Abstract: Quantum point contacts (QPC) are a key instrument in investigating the physics of edge excitations in the quantum Hall effect. However, at not-so-high bias voltage values, the predictions of the conventional point QPC model often deviate from the experimental data both in the integer and (more prominently) in the fractional quantum Hall regime. One of the possible explanations for such behaviors is the dependence of the tunneling between the edges on energy, an effect not present in the conventional model. Here we introduce two models that take QPC spatial extension into account: wide-QPC model that accounts for the distance along which the edges are in contact; long-QPC model accounts for the fact that the tunneling amplitude originates from a finite bulk gap and a finite distance between the two edges. We investigate the predictions of these two models in the integer quantum Hall regime for the energy dependence of the tunneling amplitude. We find that these two models predict opposite dependences: the amplitude decreasing or increasing away from the Fermi level. We thus elucidate the effect of the QPC geometry on the energy dependence of the tunneling amplitude and investigate its implications for transport observables. + oai:arXiv.org:2512.09045v1 cond-mat.mes-hall cond-mat.str-el - physics.app-ph quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross - http://creativecommons.org/licenses/by/4.0/ - Arup Singha, Shaili Sett, Kenji Watanabe, Takashi Taniguchi, Arindam Ghosh, Rahul Debnath + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Prasoon Kumar, Kyrylo Snizhko - 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 + High-resolution broadband characterization of resonance dispersion in an optical microresonator + https://arxiv.org/abs/2512.09475 + arXiv:2512.09475v1 Announce Type: cross +Abstract: Accurate knowledge of the uneven free spectral range of an optical microresonator, which provides direct insight into group velocity dispersion, is essential for understanding and controlling Kerr frequency comb dynamics. In this work, we present a simple and highly precise method formeasuring the free spectral range over a 5 THz bandwidth in silicon nitride microresonators, leveraging a wavemeter with 0.4 MHz resolution. Our fully fibered plug-and-play experimental setup enables the accurate extraction of resonance frequencies. By carefully analyzing the spectral position of each resonance, we measure both second- and third-order free spectral range expansion coefficients. This approach offers a robust and accessible tool for dispersion characterization in integrated photonic circuits, paving the way for next-generation of Kerr comb sources and quantum photonic technologies. + oai:arXiv.org:2512.09475v1 + physics.optics quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Misa Viveiros, Samuel S. Taylor, Cody Covington, K\'alm\'an Varga + Romain Dalidet, Adrien Bensemhoun, Gregory Sauder, Anthony Martin, David Medina, Carlos Alonso Ramos, Eric Cassan, Laurent Vivien, Jonathan Faugier Tovar, Baptiste Routier, Quentin Wilmart, S\'egol\`ene Olivier, Virginia D Auria, Laurent Labont\'e, S\'ebastien Tanzilli - 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 + Single particle dynamical signature of topology induced by single mode cavities in Su-Schrieffer-Heeger chain + https://arxiv.org/abs/2512.09520 + arXiv:2512.09520v1 Announce Type: cross +Abstract: Witnessing and tracking topological phase transitions induced by interactions with the environment is a crucial challenge. Among the various experimental approaches to detect topological properties, the Mean Chiral Displacement (MCD) has emerged as a powerful bulk probe in one-dimensional chiral systems, allowing the extraction of the topological invariant from single-particle dynamics. Here we study the dynamics of a single particle in a one-dimensional Su-Schrieffer-Heeger chain coupled to multiple cavity modes via inter-cell hopping terms, focusing on the out-of-equilibrium behavior of the MCD. We show that, whenever the frequency is larger than the static hopping amplitudes, the coupling induces a discontinuous jump in the MCD, already at small times, signaling that such a coupling also leaves a signature in the survival edge probability when the dynamics are initialized at one of the two edges. For frequencies comparable to the static hopping amplitudes, topological order competes with dissipative effects, which makes the MCD behave smoothly, retaining information about the driven-dissipative topology. + oai:arXiv.org:2512.09520v1 + cond-mat.stat-mech quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Tetsufumi Tanamoto, Keiji Ono + Fabrizio Pavan, Grazia Di Bello, Giulio De Filippis, Carmine Antonio Perroni - 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 - 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 - - - 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 + Unified theory of local integrals of motion + https://arxiv.org/abs/2512.09595 + arXiv:2512.09595v1 Announce Type: cross +Abstract: Many-body localization (MBL) is understood theoretically through the existence of an extensive number of local integrals of motion (LIOMs). These conserved quantities are related to the microscopic quantum degrees of freedom that are spatially localized. Here, we present a general framework for constructing exact LIOMs with the desired locality and quantum numbers supplied as input rather than arising as emergent properties. We show that one can express the task of finding LIOMs as an optimization problem. In simple cases, solving this problem amounts to matrix diagonalization, while in more complex settings, it connects to the question of finding classical ground states of spin-glass models. We illustrate our theory using paradigmatic examples of single-particle Anderson localization and MBL in interacting spin chains. These developments unify previous results and reveal intriguing connections among many-body localization, spin-glass physics and constrained optimization problems. + oai:arXiv.org:2512.09595v1 + cond-mat.dis-nn + math-ph + math.MP quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Florian Lange, Frank G\"ohmann, Gerhard Wellein, Holger Fehske + Ben Craps, Oleg Evnin, Dmitry Kovrizhin, Gabriele Pascuzzi - 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 + Programmable Assembly of Ground State Fermionic Tweezer Arrays + https://arxiv.org/abs/2512.09849 + arXiv:2512.09849v1 Announce Type: cross +Abstract: We demonstrate deterministic preparation of arbitrary two-component product states of fermionic $^6$Li atoms in an 8$\times$8 optical tweezer array, achieving motional ground-state fidelities above 98.5\%. Leveraging the large differential magnetic moments for spin-resolution, with parallelized site- and number-resolved control, our approach addresses key challenges for low-entropy quantum state engineering. Combined with high-fidelity spin-, site-, and density-resolved readout within a single \qty{20}{\us} exposure, and \qty{3}{\s} experimental cycles, these advances establish a fast, scalable, and programmable architecture for fermionic quantum simulation. + oai:arXiv.org:2512.09849v1 + cond-mat.quant-gas + physics.atom-ph quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross http://creativecommons.org/licenses/by/4.0/ - Subhajit Barman, K. Hari + Naman Jain, Jin Zhang, Marcus Culemann, Philipp M. Preiss - 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 + Photon emission by vortex particles accelerated in a linac + https://arxiv.org/abs/2512.09921 + arXiv:2512.09921v1 Announce Type: cross +Abstract: We study the photon emission by charged spinless particles with phase vortices and an orbital angular momentum (OAM) projection in longitudinal electric and magnetic fields within the scalar QED. A realistic wave packet of an electron or ion accelerated by a radio-frequency wave locally feels a constant and spatially homogeneous field, which allows us to develop an effective model for losing the angular momentum of the vortex particle due to photon emission. For the fields typical for accelerator facilities, we find that an effective lifetime of the vortex state greatly exceeds the acceleration time. This proves that the acceleration of vortex electrons, ions, muons, and so forth to relativistic energies is possible in conventional linacs, as well as in the wake-field accelerators with higher field gradients, the OAM losses due to the photon emission are mostly negligible, and that the vortex quantum state is highly robust against these losses. + oai:arXiv.org:2512.09921v1 + hep-ph + physics.acc-ph quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Florian Schoeppl, Alina Mrenca-Kolasinska, Ming-Hao Liu, Korbinian Schwarzmaier, Klaus Richter, Angelika Knothe + http://creativecommons.org/licenses/by/4.0/ + A. Yu. Murtazin, G. K. Sizykh, D. V. Grosman, U. G. Rybak, A. A. Shchepkin, D. V. Karlovets - 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 + Connecting single-layer $t$-$J$ to Kondo lattice models: Exploration with cold atoms + https://arxiv.org/abs/2512.09926 + arXiv:2512.09926v1 Announce Type: cross +Abstract: The Kondo effect, a hallmark of many-body physics, emerges from the antiferromagnetic coupling between localized spins and conduction fermions, leading to a correlated many-body singlet state. Here we propose to use the mixed-dimensional (mixD) bilayer Hubbard geometry as a platform to study Kondo lattice physics with current ultracold atom experiments. At experimentally feasible temperatures, we predict that key features of the Kondo effect can be observed, including formation of the Kondo cloud around a single impurity and the competition of singlet formation with Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions for multiple impurities, summarized in the Doniach phase diagram. Moreover, we show that the mixD platform provides a natural bridge between the Doniach phase diagram of the Kondo lattice model, relevant to heavy-fermion materials, and the phase diagram of cuprate superconductors as described by a single-layer Zhang-Rice type $t$-$J$ model: It is possible to continuously tune between the two regimes by changing the interlayer Kondo coupling. Our findings demonstrate that the direct connection between high-temperature superconductivity and heavy-fermion physics can be experimentally studied using currently available quantum simulation platforms. + oai:arXiv.org:2512.09926v1 + cond-mat.quant-gas cond-mat.str-el quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jonas B. Rigo, Markus Schmitt + Hannah Lange, Eugene Demler, Jan von Delft, Annabelle Bohrdt, Fabian Grusdt - 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 + Higher-dimensional Euclidean and non-Euclidean structures in planar circuit quantum electrodynamics + https://arxiv.org/abs/2108.08854 + arXiv:2108.08854v2 Announce Type: replace +Abstract: We show that a recent proposal for simulating planar hyperbolic lattices with circuit quantum electrodynamics can be extended to accommodate also higher dimensional lattices in Euclidean and non-Euclidean spaces if one allows for circuits with more than three polygons at each vertex. The quantum dynamics of these circuits, which can be constructed with present-day technology, are governed by effective tight-binding Hamiltonians corresponding to higher-dimensional Kagom\'{e}-like structures ($n$-dimensional zeolites), which are well known to exhibit strong frustration and flat bands. We analyze the relevant spectra of these systems and derive an exact expression for the fraction of flat-band states. Our results expand considerably the range of non-Euclidean geometry realizations with circuit quantum electrodynamics. + oai:arXiv.org:2108.08854v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - T. E. Bikbaev, M. Yu. Khlopov, A. G. Mayorov - - - 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 - Wed, 10 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Baptiste Coquinot, Ragheed Alhyder, Alberto Cappellaro, Mikhail Lemeshko - - - 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 + gr-qc hep-th - math-ph - math.MP - quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - A. J. D. Farias Junior, A. Smirnov, Herondy F. Santana Mota, E. R. Bezerra de Mello + Thu, 11 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Alberto Saa, Eduardo Miranda, Francisco Rouxinol - 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 + Performance Analysis of Quantum CSS Error-Correcting Codes via MacWilliams Identities + https://arxiv.org/abs/2305.01301 + arXiv:2305.01301v3 Announce Type: replace +Abstract: We analyze the performance of quantum stabilizer codes, one of the most important classes for practical implementations, on both symmetric and asymmetric quantum channels. To this aim, we first derive the weight enumerator (WE) for the undetectable errors based on the quantum MacWilliams identities. The WE is then used to evaluate tight upper bounds on the error rate of CSS quantum codes with \acl{MW} decoding. For surface codes we also derive a simple closed form expression of the bounds over the depolarizing channel. We introduce a novel approach that combines the knowledge of WE with a logical operator analysis, allowing the derivation of the exact asymptotic error rate for short codes. For example, on a depolarizing channel with physical error rate $\rho \to 0$, the logical error rate $\rho_\mathrm{L}$ is asymptotically $\rho_\mathrm{L} \approx 16 \rho^2$ for the $[[9,1,3]]$ Shor code, $\rho_\mathrm{L} \approx 16.3 \rho^2$ for the $[[7,1,3]]$ Steane code, $\rho_\mathrm{L} \approx 18.7 \rho^2$ for the $[[13,1,3]]$ surface code, and $\rho_\mathrm{L} \approx 149.3 \rho^3$ for the $[[41,1,5]]$ surface code. For larger codes our bound provides $\rho_\mathrm{L} \approx 1215 \rho^4$ and $\rho_\mathrm{L} \approx 663 \rho^5$ for the $[[85,1,7]]$ and the $[[181,1,10]]$ surface codes, respectively. Finally, we extend our analysis to include realistic, noisy syndrome extraction circuits by modeling error propagation throughout gadgets. This enables estimation of logical error rates under faulty measurements. The performance analysis serves as a design tool for developing fault-tolerant quantum systems by guiding the selection of quantum codes based on their error correction capability. Additionally, it offers a novel perspective on quantum degeneracy, showing it represents the fraction of non-correctable error patterns shared by multiple logical operators. + oai:arXiv.org:2305.01301v3 quant-ph - cond-mat.str-el - hep-th - math-ph - math.MP - math.PR - Wed, 10 Dec 2025 00:00:00 -0500 + cs.IT + math.IT + Thu, 11 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1007/s00023-021-01087-4 - Annales Henri Poincare, Vol. 23, pp. 141-222 (2022) - C\'ecilia Lancien, David P\'erez-Garc\'ia + Diego Forlivesi, Lorenzo Valentini, Marco Chiani - 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 + Quantum Communication Networks Enhanced by Distributed Quantum Memories + https://arxiv.org/abs/2403.16367 + arXiv:2403.16367v2 Announce Type: replace +Abstract: Building large-scale quantum communication networks has its unique challenges. Here, we demonstrate that a network-wide synergistic usage of quantum memories distributed in a quantum communication network offers a fundamental advantage. We first map the problem of quantum communication with local usage of memories into a classical continuum percolation model. Then, we show that this mapping can be improved through a cooperation of quantum distillation and relay protocols via remote access to distributed memories. This improved mapping, which we term $\alpha$-percolation, can be formulated in terms of graph-merging rules, analogous to the decimation rules of the renormalization group treatment of disordered quantum magnets. These rules can be performed in any order, yielding the same optimal result that is characterized by the emergence of a ``positive feedback'' mechanism and the formation of spatially disconnected ``hopping'' communication components -- both marking significant improvements beyond the traditional point-to-point consideration of quantum communication in networked structures. + oai:arXiv.org:2403.16367v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1088/1367-2630/ac9fe9 - New J. Phys. 24 122001 (2022) - Anton N. Vetlugin, Ruixiang Guo, Cesare Soci, Nikolay I. Zheludev + http://creativecommons.org/licenses/by/4.0/ + Xiangyi Meng, Nicol\`o Lo Piparo, Kae Nemoto, Istv\'an A. Kov\'acs - 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 + A simple fourth order propagator based on the Magnus expansion in the Liouville space: Application to a $\Lambda$-system and assessment of the rotating wave approximation + https://arxiv.org/abs/2407.03576 + arXiv:2407.03576v2 Announce Type: replace +Abstract: A simple 4th order propagator [Ture and Jang, {\it J. Phys. Chem. A.} {\bf 128}, 2871 (2024)] based on the Magnus expansion (ME) is extended to the Liouville space for both closed-system and Lindbladian open-system quantum dynamics. For both dynamics, commutator free versions of 4th order propagators are provided as well. These propagators are then applied to the dynamics of a driven $\Lambda$-system, where Lindblad terms represent the effect of a photonic bath. For both dynamics, the accuracy of the rotating wave approximation (RWA) for the matter-radiation interaction is assessed. We confirmed reasonable performance of RWA for weak and resonant fields. However, small errors appear for moderate fields and substantial errors can be found for strong fields where coherent population trapping can still be expected. We also found that the presence of bath for open system quantum dynamics consistently reduces the errors of the RWA. These results provide a quantitative information on how the RWA breaks down beyond weak field or for non-resonant cases. Major results are benchmarked against results of our 6th order ME-based propagator. We also provide numerical comparison of our algorithms with other 4th order algorithms for the $\Lambda$-system. These confirm reasonable performance of out simple propagators and the improvement gained through commutator-free expressions. + oai:arXiv.org:2407.03576v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.atom-ph + physics.chem-ph + physics.optics + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Kees van Hee, Kees van Berkel, Jan de Graaf + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Taner M. Ture, Changbong Hyeon, Seogjoo J. Jang - 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 + A Novel Stabilizer-based Entanglement Distillation Protocol for Qudits + https://arxiv.org/abs/2408.02383 + arXiv:2408.02383v3 Announce Type: replace +Abstract: Entanglement distillation, the process of converting weakly entangled states into maximally entangled ones using Local Operations and Classical Communication (LOCC), is pivotal for robust entanglement-assisted quantum information processing in error-prone environments. A construction based on stabilizer codes offers an effective method for designing such protocols. By analytically investigating the effective action of stabilizer protocols for systems of prime dimension $d$, we establish a standard form for the output states of recurrent stabilizer-based distillation. This links the properties of input states, stabilizers, and encodings to the properties of the protocol. Based on those insights, we present a novel two-copy distillation protocol, applicable to all bipartite states in prime dimension, that maximizes the fidelity increase per iteration for Bell-diagonal states. The power of this framework and the protocol is demonstrated through numerical investigations, which provide evidence for superior performance in terms of efficiency and distillability of low-fidelity states compared to other well-established recurrence protocols. By elucidating the interplay between states, errors, and protocols, our contribution advances the systematic development of highly effective distillation protocols, enhancing our understanding of distillability. + oai:arXiv.org:2408.02383v3 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 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 + Christopher Popp, Tobias C. Sutter, Beatrix C. Hiesmayr - 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 + Multipartite entanglement vs nonlocality for two families of $N$-qubit states + https://arxiv.org/abs/2409.10888 + arXiv:2409.10888v2 Announce Type: replace +Abstract: Entangled states of multiple qubits can violate Bell-type inequalities indicating nonlocal behavior of multiqubit quantum correlations. We analyze the relation between multipartite entanglement and genuine multipartite nonlocality, characterized by Svetlichny inequality violations, for two families of $N-$qubit states. We show that for the generalized GHZ family of states, Svetlichny inequality is not violated when the $n-$tangle is less than $1/2$ for any even number of qubits. On the other hand, the maximal slice states always violate the Svetlichny inequality when $n-$tangle is nonzero, and the violation increases monotonically with tangle. Our work generalizes the relations between tangle and Svetlichny inequality violations previously derived for three qubits. + oai:arXiv.org:2409.10888v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Jonathan Conrad, Jens Eisert, Steven T. Flammia + 10.1103/btbb-p514 + Phys. Rev. Research 7, 033289, Published 26 September, 2025 + Sanchit Srivastava, Shohini Ghose - 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 + Universal adapters between quantum LDPC codes + https://arxiv.org/abs/2410.03628 + arXiv:2410.03628v3 Announce Type: replace +Abstract: We propose the repetition code adapter as a way to perform joint logical Pauli measurements within a quantum low-density parity check (LDPC) codeblock or between separate such codeblocks. This adapter is universal in the sense that it works regardless of the LDPC codes involved and the Paulis being measured. The construction achieves joint logical Pauli measurement of $t$ weight $O(d)$ operators using $O(td\log^2d)$ additional qubits and checks and $O(d)$ time. We also show for some geometrically-local codes in fixed $D\ge2$ dimensions that only $O(td)$ additional qubits and checks are required instead. By extending the adapter in the case $t=2$, we construct a toric code adapter that uses $O(d^2)$ additional qubits and checks to perform targeted logical CNOT gates on arbitrary LDPC codes via Dehn twists. To obtain some of these results, we develop a novel weaker form of graph edge expansion. + oai:arXiv.org:2410.03628v3 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - 10.1140/epjp/s13360-025-06903-y - The European Physical Journal Plus 140, 954 (2025) - Luca Maggio, Danilo Triggiani, Paolo Facchi, Vincenzo Tamma + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Esha Swaroop, Tomas Jochym-O'Connor, Theodore J. Yoder - 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 + Transient concurrence for copropagating entangled bosons and fermions + https://arxiv.org/abs/2410.12095 + arXiv:2410.12095v2 Announce Type: replace +Abstract: Transient dynamics of copropagating entangled bosons and fermions remains an unexplored aspect of quantum mechanics. We investigate how entanglement affects the spatiotemporal evolution of the particles using a modified version of the quantum shutter model. We derive a transient concurrence to characterize momentum-space entanglement, and show that it modulates the interference correlation of the joint probability density, allowing us to visualize the active regions where probabilistic bunching and antibunching phenomena emerge. Furthermore, we derive analytical expressions that reveal a direct connection between entanglement and the characteristic oscillations of the Hanbury-Brown and Twiss (HBT) effect, highlighting the modulation of the phenomenon by quantum concurrence. This work introduces a temporal indicator of entanglement for a system of two coherent copropagating modes establishing a direct relationship with HBT-type interference patterns, providing a theoretical framework to explore the manifestation of entanglement in transient regimes. + oai:arXiv.org:2410.12095v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 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 + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Miguel \'Angel Ter\'an, Roberto Romo, Gast\'on Garc\'ia-Calder\'on - 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 + General, efficient, and robust Hamiltonian engineering + https://arxiv.org/abs/2410.19903 + arXiv:2410.19903v3 Announce Type: replace +Abstract: Implementing the time evolution under a desired target Hamiltonian is critical for various applications in quantum science. Due to the exponential increase in the number of parameters with system size and experimental imperfections, this task can be challenging in quantum many-body settings. + We introduce an efficient and robust scheme to engineer arbitrary local many-body Hamiltonians. To this end, our scheme applies single-qubit $\pi$ or $\pi/2$ pulses to an always-on system Hamiltonian, which we assume to be native to a given platform. These sequences are constructed by efficiently solving a linear program (LP) which minimizes the total evolution time. In this way, we can engineer target Hamiltonians that are only limited by the locality of the interactions in the system Hamiltonian. Based on average Hamiltonian theory and using robust composite pulses, we make our schemes robust against errors, including finite pulse time errors and various control errors. + To demonstrate the performance of our scheme, we provide numerical simulations. In particular, we solve the Hamiltonian engineering problem on a laptop for arbitrary two-local Hamiltonians on a 2D square lattice with $196$ qubits in only $60$ seconds. Moreover, we simulate the engineering of general Heisenberg Hamiltonians from Ising Hamiltonians using imperfect single-qubit pulses for smaller system sizes and achieve a fidelity exceeding $99.9\%$, which is orders of magnitude better than non-robust implementations. + oai:arXiv.org:2410.19903v3 quant-ph - cond-mat.mes-hall - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 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 + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/9yxv-tdqr + PRX Quantum 6, 040346 (2025) + Pascal Ba{\ss}ler, Markus Heinrich, Martin Kliesch - 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 + Efficient explicit circuit for quantum state preparation of piecewise continuous functions + https://arxiv.org/abs/2411.01131 + arXiv:2411.01131v4 Announce Type: replace +Abstract: Efficiently uploading data into quantum states is essential for many quantum algorithms to achieve advantage across various applications. In this paper, we address this challenge by developing a method to upload a polynomial function $f(x)$ on the interval $x \in [-1,1]$ into a pure quantum state consisting of qubits, where a discretized $f(x)$ is the amplitude of this state. The preparation cost has $\mathcal{O}(n\log n)$ scaling in the number of qubits $n$ and linear scaling with the degree of the polynomial $Q$. This efficiency allows the preparation of states whose amplitudes correspond to high-degree polynomials (up to $10^4$), enabling accurate approximation of functions that admit efficient polynomial series representations and whose amplitude profiles are not extremely localized. We provide a fully explicit circuit realization, based on four real polynomials that meet specific parity and boundedness conditions. We extend this construction to cover piece-wise polynomial functions, a case not previously addressed explicitly in the literature, the algorithm scaling linearly with the number of piecewise parts. Our method achieves efficient quantum circuit implementation and we present detailed gate counting and resource analysis. + oai:arXiv.org:2411.01131v4 quant-ph - cond-mat.other - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Michele Viscardi, Marcello Dalmonte, Alioscia Hamma, Emanuele Tirrito + Nikita Guseynov, Nana Liu - 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 + Machine Learning for Arbitrary Single-Qubit Rotations on an Embedded Device + https://arxiv.org/abs/2411.13037 + arXiv:2411.13037v2 Announce Type: replace +Abstract: Here we present a technique for using machine learning (ML) for single-qubit gate synthesis on field programmable logic for a superconducting transmon-based quantum computer based on simulated studies. Our approach is multi-stage. We first bootstrap a model based on simulation with access to the full statevector for measuring gate fidelity. We next present an algorithm, named adapted randomized benchmarking (ARB), for fine-tuning the gate on hardware based on measurements of the devices. We also present techniques for deploying the model on programmable devices with care to reduce the required resources. While the techniques here are applied to a transmon-based computer, many of them are portable to other architectures. + oai:arXiv.org:2411.13037v2 quant-ph - cond-mat.dis-nn - cond-mat.stat-mech - math-ph - math.MP - Wed, 10 Dec 2025 00:00:00 -0500 + cs.ET + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Eric R. Anschuetz + 10.1007/s42484-024-00214-8 + Madhav Narayan Bhat, Marco Russo, Luca P. Carloni, Giuseppe Di Guglielmo, Farah Fahim, Andy C. Y. Li, Gabriel N. Perdue - 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 + Continuous-variable quantum communication + https://arxiv.org/abs/2501.12801 + arXiv:2501.12801v2 Announce Type: replace +Abstract: Tremendous progress in experimental quantum optics during the past decades enabled the advent of quantum technologies, one of which is quantum communication. Aimed at novel methods for more secure or efficient information transfer, quantum communication has developed into an active field of research and proceeds toward full-scale implementations and industrialization. Continuous-variable methods of multi-photon quantum state preparation, manipulation, and coherent detection, as well as the respective theoretical tools of phase-space quantum optics, offer the possibility to make quantum communication efficient, applicable and accessible, thus boosting the development of the field. We review the methodology, techniques and protocols of continuous-variable quantum communication, from the first theoretical ideas, through milestone implementations, to the recent developments, covering quantum key distribution as well as other quantum communication schemes, suggested on the basis of continuous-variable states and measurements. + oai:arXiv.org:2501.12801v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Charlotte B\"acker, Valentin Link, Walter T. Strunz + Vladyslav C. Usenko, Antonio Ac\'in, Romain All\'eaume, Ulrik L. Andersen, Eleni Diamanti, Tobias Gehring, Adnan A. E. Hajomer, Florian Kanitschar, Christoph Pacher, Stefano Pirandola, Valerio Pruneri - 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 + Temperature and non-Markovian parameter estimation in quantum Brownian motion + https://arxiv.org/abs/2504.08529 + arXiv:2504.08529v3 Announce Type: replace +Abstract: We investigate a quantum metrological protocol operating in a non-Markovian environment by employing the quantum Brownian motion (QBM) model, in which the system is linearly coupled to a reservoir of harmonic oscillators. Specifically, we use a position-momentum (PM) correlated Gaussian state as a probe to examine how memory effects influence the evolution of the system's covariance matrix in the weak coupling regime under both high- and low-temperature conditions. To confirm the presence of non-Markovian behavior, we apply two well-established non-Markovianity quantifiers. Furthermore, we estimate both the channel's sample temperature and its non-Markovianity witness parameter. Our results demonstrate that non-Markovianity and PM correlations can jointly be valuable resources to enhance metrological performance. + oai:arXiv.org:2504.08529v3 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 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 + 10.1103/c87r-22mn + Jo\~ao C. P. Porto, Carlos H. S. Vieira, Irismar G. da Paz, Pedro R. Dieguez, Lucas S. Marinho - 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 + Entangled Subspaces through Algebraic Geometry + https://arxiv.org/abs/2504.11525 + arXiv:2504.11525v2 Announce Type: replace +Abstract: We propose an algebraic geometry-inspired approach for constructing entangled subspaces within the Hilbert space of a multipartite quantum system. Specifically, our method employs a modified Veronese embedding, restricted to the conic, to define subspaces within the symmetric part of the Hilbert space. By utilizing this technique, we construct the minimal-dimensional, non-orthogonal yet Unextendible Product Basis (nUPB), enabling the decomposition of the multipartite Hilbert space into a two-dimensional subspace, complemented by a Genuinely Entangled Subspace (GES) and a maximal-dimensional Completely Entangled Subspace (CES). In multiqudit systems, we determine the maximum achievable dimension of a symmetric GES and demonstrate its realization through this construction. Furthermore, we systematically investigate the transition from the conventional Veronese embedding to the modified one by imposing various constraints on the affine coordinates, which, in turn, increases the CES dimension while reducing that of the GES. + oai:arXiv.org:2504.11525v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + math-ph + math.AG + math.MP + Thu, 11 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 + http://creativecommons.org/licenses/by/4.0/ + Masoud Gharahi, Stefano Mancini - 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 + Benchmarking data encoding methods in Quantum Machine Learning + https://arxiv.org/abs/2505.14295 + arXiv:2505.14295v2 Announce Type: replace +Abstract: Data encoding plays a fundamental and distinctive role in Quantum Machine Learning (QML). While classical approaches process data directly as vectors, QML may require transforming classical data into quantum states through encoding circuits, known as quantum feature maps or quantum embeddings. This step leverages the inherently high-dimensional and non-linear nature of Hilbert space, enabling more efficient data separation in complex feature spaces that may be inaccessible to classical methods. This encoding part significantly affects the performance of the QML model, so it is important to choose the right encoding method for the dataset to be encoded. However, this choice is generally arbitrary, since there is no "universal" rule for knowing which encoding to choose based on a specific set of data. There are currently a variety of encoding methods using different quantum logic gates. We studied the most commonly used types of encoding methods and benchmarked them using different datasets. + oai:arXiv.org:2505.14295v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.AI + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alberto J. B. Rosal, Patrick P. Potts, Gabriel T. Landi + Orlane Zang, Gr\'egoire Barru\'e, Tony Quertier - 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 + Hierarchic superradiant phases in anisotropic Dicke model + https://arxiv.org/abs/2505.21169 + arXiv:2505.21169v3 Announce Type: replace +Abstract: We revisit the phase diagram of an anisotropic Dicke model by revealing the non-analyticity induced by underlying exceptional points. We find that, from a dynamical perspective, the conventional superradiant phase can be further separated into three regions, in which the systems are characterized by different effective Hamiltonians, including the harmonic oscillator, the inverted harmonic oscillator, and their respective counterparts. We employ the Loschmidt echo to characterize different quantum phases by analyzing the quench dynamics of a trivial initial state. Numerical simulations for finite systems confirm our predictions about the existence of hierarchic superradiant phases. + oai:arXiv.org:2505.21169v3 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.str-el + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Viktor Khinevich, Yasunori Lee, Nobuyuki Yoshioka, Wataru Mizukami + D. K. He, Z. Song - 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 + Giant atom with disorders: Effects from imperfect couplings + https://arxiv.org/abs/2506.03628 + arXiv:2506.03628v3 Announce Type: replace +Abstract: The study of giant atoms goes beyond the local interaction paradigm in the conventional quantum optics, and predicts novel phenomena, such as oscillating bound states in the continuum (BICs) and decoherence-free interaction (DFI) that do not exist in small atoms, for some particular parameter settings of coupling positions and strengths. However, in the realistic experiments to implement giant-atom systems, there is always some level of disorder both in coupling positions and strengths. In this work, we investigate the effects of disorder on the phenomena related to giant atoms. We find that the giant-atom related phenomena are robust to both disorders of coupling positions and strengths in the Markovian regime, but more sensitive to the disorder of coupling positions in the non-Markovian regime. Our work shows that, to observe the non-Markovian phenomenon such as (oscillating) BICs in giant-atom systems, more precision is needed to control the disorder of coupling positions than that of the coupling strengths in the experiments. + oai:arXiv.org:2506.03628v3 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Noah B. Kerzner, Federico Galeazzi, Rafael I. Nepomechie + 10.1103/1px2-2db4 + Muming Han, Lingzhen Guo - 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 + Inline Quantum Measurements with SNSPDs Coupled to Photonic Bound States + https://arxiv.org/abs/2506.07029 + arXiv:2506.07029v2 Announce Type: replace +Abstract: We report the realization of inline quantum measurements with waveguide-integrated superconducting nanowire single-photon detectors (SNSPDs). To suppress parasitic scattering at detector terminations, while ensuring compatibility with standard photonic substrates and cryogenic operation, we developed a photonic bound states in the continuum (BIC) platform based on etchless polymer waveguides. We show BIC-coupled inline detectors with on-chip efficiency exceeding 80%, recovery time of less than 2 ns, and intrinsic jitter of less than 70 ps. As a proof of principle, we implement Hanbury Brown and Twiss interferometry and photon number resolution with two collinear detectors within a footprint of $60 \cdot 6$ $\mu m^2$. The concept of inline quantum measurements could be further developed to support more complex circuit functionalities, such as higher-order correlation measurements, quantum state tomography, and multi-photon subtraction, within a compact architecture. + oai:arXiv.org:2506.07029v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Achraf Khoudiri, Abderrahim El Allati, Youssef Khlifi, Khadija El Anouz, \"Ozg\"ur E. M\"ustecapl{\i}o\u{g}lu + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Filippo Martinelli, Anton N. Vetlugin, Shuyu Dong, Darren M. Z. Koh, Mariia Sidorova, Christian Kurtsiefer, Cesare Soci - 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 + Certifying asymmetry in the configuration of three qubits + https://arxiv.org/abs/2506.09939 + arXiv:2506.09939v2 Announce Type: replace +Abstract: Symmetry restrictions limit the types of tasks that can be achieved with a given set of quantum states. Therefore, any breaking of these symmetries could potentially be exploited as a resource for quantum communication. Here we demonstrate this operationally by certifying asymmetry in the configuration of the Bloch vectors of a set of three unknown qubit states within the dimensionally bounded prepare-and-measure scenario. To do this, we construct a linear witness from three simpler witnesses as building blocks, each featuring, along with two binary measurement settings, three preparations; two of them are associated with the certification task, while the third one serves as an auxiliary. The final witness is chosen to self-test some target configuration. We numerically derive a bound $Q_{\text{mirror}}$ for any mirror-symmetric configuration, thereby certifying asymmetry if this bound is exceeded (e.g. experimentally) for the unknown qubit configuration. We also consider the gap $(Q_{\text{max}}-Q_{\text{mirror}})$ between the analytically derived overall quantum maximum $Q_{\text{max}}$ and the mirror-symmetric bound, and use it as a quantifier of asymmetry in the target configuration. Numerical optimization shows that the most asymmetric configuration then forms a right scalene triangle on the unit Bloch sphere. Finally, we implement our protocol on a public quantum processor, where a clear violation of the mirror-symmetric bound certifies asymmetry in the configuration of our experimental triple of qubit states. + oai:arXiv.org:2506.09939v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Nataliya Arefyeva, Evgeny Polyakov + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1088/1367-2630/ae1ce3 + New J. Phys. 27, 124501 (2025) + Abdelmalek Taoutioui, G\'abor Dr\'otos, Tam\'as V\'ertesi - 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 + Higher-Order Adiabatic Elimination in Atom-Cavity Systems and Its Impact on Spin-Squeezing Generation + https://arxiv.org/abs/2506.22383 + arXiv:2506.22383v3 Announce Type: replace +Abstract: Spin-squeezed states are metrologically useful quantum states where entanglement allows for enhanced sensing with respect to the standard quantum limit. Key challenges include the efficient preparation of spin-squeezed states and the scalability of estimation precision with the number $N$ of probes. Recently, in the context of the generation of spin-squeezed states via coupling of three-level atoms to an optical cavity, it was shown that increasing the atom-cavity coupling can be detrimental to spin squeezing generation, an effect that is not captured by the standard second-order adiabatic cavity removal approximation. We describe adiabatic elimination techniques to derive an effective Lindblad master equation up to third order for the atomic degrees of freedom. Numerical simulations show that the spin squeezing scalability loss is correctly reproduced by the reduced open system dynamics, highlighting the role of higher-order contributions. Furthermore, we conjecture an extension beyond leading order of the adiabatic elimination technique to the case of conditional dynamics under quantum non-demolition continuous measurement and fast cavity loss, whose reliability is again confirmed by numerical simulation of the dynamics and the corresponding behavior of spin squeezing as a function of $N$. + oai:arXiv.org:2506.22383v3 quant-ph - hep-ex - hep-th - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - 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 + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Stefano Giaccari, Giulia Dellea, Marco G. Genoni, Gianluca Bertaina - 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 + Photon condensation from thermal sources and the limits of heat engines + https://arxiv.org/abs/2507.19128 + arXiv:2507.19128v2 Announce Type: replace +Abstract: The trapping and cooling of photon gases in microcavities has been used to create Bose-Einstein condensates. We investigate the conditions required for condensation in dye-filled microcavities, with photon populations created either by driving a transition of the dye, or by coupling the cavity modes to a thermal photon reservoir such as sunlight. We find that the threshold pump temperature, above which condensation appears, is determined by the second law of thermodynamics. The minimum achievable threshold is that of a reversible three-level heat engine, which we show arises in the dye-pumped case, and for pumping of the modes of a two-level cavity. For a many-level cavity condensation occurs at a similar but higher temperature. Our results show that photon condensates can be produced by pumping with incoherent thermal sources, opening possibilities for coherent light generation, energy harvesting, and experimental studies of quantum heat engines. + oai:arXiv.org:2507.19128v2 quant-ph - physics.class-ph - physics.optics - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.quant-gas + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Valerica Raicu + http://creativecommons.org/licenses/by/4.0/ + Luisa Toledo Tude, Emily Haughton, Paul R. Eastham - 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 + Structured quantum learning via em algorithm for Boltzmann machines + https://arxiv.org/abs/2507.21569 + arXiv:2507.21569v2 Announce Type: replace +Abstract: Quantum Boltzmann machines (QBMs) are generative models with potential advantages in quantum machine learning, yet their training is fundamentally limited by the barren plateau problem, where gradients vanish exponentially with system size. We introduce a quantum version of the em algorithm, an information-geometric generalization of the classical Expectation-Maximization method, which circumvents gradient-based optimization on non-convex functions. Implemented on a semi-quantum restricted Boltzmann machine (sqRBM) -- a hybrid architecture with quantum effects confined to the hidden layer -- our method achieves stable learning and outperforms gradient descent on multiple benchmark datasets. These results establish a structured and scalable alternative to gradient-based training in QML, offering a pathway to mitigate barren plateaus and enhance quantum generative modeling. + oai:arXiv.org:2507.21569v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cs.LG + Thu, 11 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Amit Jamadagni, Eugene Dumitrescu + Takeshi Kimura, Kohtaro Kato, Masahito Hayashi - 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 + Quantum coherence and negative quasi probabilities in a contextual three-path interferometer + https://arxiv.org/abs/2507.22323 + arXiv:2507.22323v2 Announce Type: replace +Abstract: Basic quantum effects are often illustrated using single particle interferences in two-path interferometers. A wider range of non-classical phenomena can be illustrated using three-path interferometers, but the increased complexity of quantum statistics in a three-dimensional Hilbert space makes it difficult to identify a representative set of observable properties that could be used to characterize specific phenomena. Here, I propose a characterization of pure states based on a five-stage interferometer recently introduced to demonstrate the relation between different measurement contexts (Optica Quantum 1, 63 (2023)). It is shown that the orthogonality relations between the states representing the different measurement contexts can be used to classify pure states within the three-dimensional Hilbert space according to the non-classical correlations between different contexts expressed by negative Kirkwood-Dirac distributions. + oai:arXiv.org:2507.22323v2 quant-ph - cs.CC - Wed, 10 Dec 2025 00:00:00 -0500 + physics.optics + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Uma Girish + Holger F. Hofmann - 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 + Stoquasticity is not enough: towards a sharper diagnostic for Quantum Monte Carlo simulability + https://arxiv.org/abs/2508.14382 + arXiv:2508.14382v2 Announce Type: replace +Abstract: Quantum Monte Carlo (QMC) methods are powerful tools for simulating quantum many-body systems, yet their applicability is limited by the infamous sign problem. We approach this challenge through the lens of Vanishing Geometric Phases (VGP) \cite{Hen_2021}, introducing it as a `geometric' criterion for diagnosing QMC simulability. We characterize the class of VGP Hamiltonians, and analyze the complexity of recognizing this class, identifying both hard and efficiently identifiable cases. We further highlight the practical advantage of the VGP criterion by exhibiting specific Hamiltonians that are readily identified as sign-problem-free through VGP, yet whose stoquasticity is difficult to ascertain. These examples underscore the efficiency and sharpness of VGP as a diagnostic tool compared to stoquasticity-based heuristics. Beyond classification, we propose a family of VGP-inspired diagnostics that serve as quantitative indicators of sign problem severity. While exact evaluation of these quantities is generically intractable, we demonstrate their mathematical power in performing scaling analysis for the average sign under unitary transformations. Our results provide both a conceptual foundation and practical tools for understanding and mitigating the sign problem. + oai:arXiv.org:2508.14382v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.stat-mech + physics.comp-ph + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yannick Strocka, Mohamed Belhassen, Tim Schr\"oder, Gregor Pieplow + Arman Babakhani, Armen Karakashian - 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 + Magnetic noise in macroscopic quantum spatial superposition induced by inverted harmonic oscillator potential + https://arxiv.org/abs/2509.02670 + arXiv:2509.02670v2 Announce Type: replace +Abstract: We investigate a Stern-Gerlach type matter-wave interferometer where an inhomogeneous magnetic field couples to an embedded spin in a nanoparticle to create spatial superpositions. Employing a sequence of harmonic and inverted harmonic oscillator potentials created by external magnetic fields, we aim to enhance the one-dimensional superposition of a nanodiamond with mass $\sim 10^{-15}$ kg to $\sim 1 \mu$m. However, random fluctuations of the magnetic field stochastically perturbs the interferometer paths and induce dephasing. We quantitatively estimate the susceptibility of the interferometer to white noise arising from magnetic-field fluctuations. Constraining the dephasing rate \(\Gamma\) to be low enough that the final coherence \(e^{-\Gamma \tau}\leq 0.1\) (where \(\tau\) is the experimental time duration), we obtain the following bounds on the noise to signal ratios: $\delta \eta_\text{IHP}/\eta_\text{IHP}\lesssim 10^{-13}$, where $\eta_\text{IHP}$ is the magnetic field curvature that gives rise to the inverted harmonic potential, and $\delta \eta_\text{HP}/\eta_\text{HP}\lesssim 10^{-6}$, where $\eta_\text{HP}$ is the linear magnetic field gradient that gives rise to the harmonic potential. For such tiny fluctuations, we demonstrate that the Humpty-Dumpty problem arising from a mismatch in position and momentum does not cause a loss in contrast of the interferometer. Further, we show that constraining the dephasing rate leads to stricter bounds on the noise parameters than enforcing a contrast threshold, indicating that good dephasing control ensures high interferometric contrast. + oai:arXiv.org:2509.02670v2 quant-ph - cs.IT - math-ph - math.IT - math.MP - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kaiyuan Ji, Bartosz Regula + http://creativecommons.org/licenses/by/4.0/ + Sneha Narasimha Moorthy, Anupam Mazumdar - 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 + Measuring Multiparticle Indistinguishability with the Generalized Bunching Probability + https://arxiv.org/abs/2509.04550 + arXiv:2509.04550v4 Announce Type: replace +Abstract: The indistinguishability of many bosons undergoing passive linear transformations followed by number basis measurements is fully characterized by the visible state of the bosons. However, measuring all the parameters in the visible state is experimentally demanding. In this work, we seek to perform partial characterization of the visible state by measuring properties of it that are available after randomization. First we study the case where the occupied visible modes are randomly permuted, and second we study the case where Haar random linear optical unitaries are applied. In each case, we find that the generalized bunching probability -- which is the probability that all the input bosons arrive in a given subset of the output modes -- obeys monotonicity with respect to some partial order of distinguishability of the input bosons. As an intermediate result, we show that Lieb's permanental-dominance conjecture for immanants is equivalent to the following statement: for states that are invariant under permutations of the occupied visible modes, the generalized bunching probability is maximized when the bosons are perfectly indistinguishable. We also prove that a consequence of the monotonicity of the generalized bunching probability after Haar averaging is that this average is maximized when the bosons are perfectly indistinguishable. Finally, we discuss applications of our results to thermometry of cold-atom systems. + oai:arXiv.org:2509.04550v4 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Stefano Scali, Josh Kirsopp, Antonio M\'arquez Romero, Micha{\l} Krompiec + Shawn Geller, Emanuel Knill - 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 + Diffraction by Circular and Triangular Apertures as a Diagnostic Tool of Twisted Matter Waves + https://arxiv.org/abs/2510.00826 + arXiv:2510.00826v3 Announce Type: replace +Abstract: We study diffraction of twisted matter waves (electrons and light ions carrying orbital angular momentum $\ell/\hbar=0,\pm1,\pm2,\ldots$ by circular and triangular apertures. Within the scalar Kirchhoff-Fresnel framework, circular apertures preserve cylindrical symmetry and produce ringlike far-field profiles whose radii and widths depend on $|\ell|$ but are insensitive to its sign. In contrast, equilateral triangles break axial symmetry and yield structured patterns that encode both the magnitude and the sign of $\ell$. A transparent Fraunhofer mapping links detector coordinates to the Fourier plane, explaining the $(|\ell|+1)$-lobe rule and the sign-dependent rotation of the pattern. We validate these results for both ideal Bessel beams and localized Laguerre-Gaussian packets, and we cross-check them by split-step Fourier propagation of the time-dependent Schr"odinger equation. From these analyses we extract practical design rules (Fraunhofer distance, lattice pitch, detector sampling) relevant to OAM diagnostics with moderately relativistic electrons with $E_{\rm kin}\sim0.1$ to $5$ MeV and light ions with $E_{\rm kin}\sim0.1$ to $1$ MeV/u. Our results establish triangular diffraction as a simple, passive, and robust method for reading out the OAM content of structured quantum beams. + oai:arXiv.org:2510.00826v3 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + hep-ph + physics.acc-ph + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yohei Ibe, Yutaka Hirano, Yasuo Ozu, Toru Kawakubo, Keisuke Fujii + 10.1103/z2rs-2ryl + Maksim Maksimov, Nikita Borodin, Daria Kargina, Dmitry Naumov, Dmitry Karlovets - 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 + Good quantum codes with addressable and parallelizable transversal non-Clifford gates + https://arxiv.org/abs/2510.19809 + arXiv:2510.19809v2 Announce Type: replace +Abstract: In this work, we prove that for any $m>1$, there exists a family of good qudit quantum codes supporting transversal logical $\mathsf{C}^{m-1}\mathsf{Z}$ gates that can address specified logical qudits and be largely executed in parallel. Building on the family of good quantum error-correcting codes presented in He et al. (2025), which support addressable and transversal logical $\mathsf{CCZ}$ gates, we extend their framework and show how to perform large sets of gates in parallel. The construction relies on the classical algebraic geometry codes of Stichtenoth (IEEE Trans. Inf. Theory, 2006). Our results lead to a substantial reduction in the depth overhead of multi-control-$Z$ circuits. In particular, we show that the minimal depth of any logical $\mathsf{C}^{m-1}\mathsf{Z}$ circuit involving qudits from $m$ distinct code blocks is upper bounded by $O(k^{m-1})$, where $k$ is the code dimension. While this overhead is optimal for dense $\mathsf{C}^{m-1}\mathsf{Z}$ circuits, for sparse circuits we discuss how the depth overhead can be significantly reduced by exploiting the structure of the quantum code. + oai:arXiv.org:2510.19809v2 quant-ph - cs.ET - Wed, 10 Dec 2025 00:00:00 -0500 + cs.IT + math.IT + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Miguel Angel Lopez-Ruiz, Emily L. Tucker, Emma M. Arnold, Evgeny Epifanovsky, Ananth Kaushik, Martin Roetteler + http://creativecommons.org/licenses/by/4.0/ + Virgile Gu\'emard - 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 + The three kinds of three-qubit entanglement + https://arxiv.org/abs/2511.07617 + arXiv:2511.07617v2 Announce Type: replace +Abstract: We construct an important missing piece in the entanglement theory of pure three-qubit states, which is a polynomial measure of W-entanglement, working in parallel to the three-tangle, which is a polynomial measure of GHZ-entanglement, and to the bipartite concurrence, which is a polynomial measure of bipartite entanglement. We also show that these entanglement measures are ordered, the bipartite measure is larger than the W measure, which is larger than the GHZ measure. It is meaningful then to consider these three types of three-qubit entanglement, which are also ordered, bipartite is weaker than W, which is weaker than GHZ, in parallel to the order of the three equivalence classes of entangled three-qubit states. + oai:arXiv.org:2511.07617v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3390/e27121239 - Entropy 2025, 27(12), 1239 - Da-Wei Luo, Edward Yu, Ting Yu + Szil\'ard Szalay - 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 + Quantum resource degradation theory within the framework of observational entropy decomposition + https://arxiv.org/abs/2511.22350 + arXiv:2511.22350v2 Announce Type: replace +Abstract: We introduce a theory of quantum resource degradation grounded in a decomposition of observational entropy, which partitions the total resource into inter-block coherence ($\mathcal{C}_{\text{rel}}$) and intra-block noise ($\mathcal{D}_{\text{rel}}$). Under free operations, the total quantum resource is transformed into classical noise while its overall quantity remains conserved. We demonstrate that the metric $\eta$ functions as a diagnostic indicator, providing a new lens on optimization stagnation, particularly the barren plateau phenomenon (BPP) in variational quantum algorithms (VQAs). We substantiate this framework through rigorous mathematical analysis and numerical simulations, and we explore how these channels can be physically implemented in real quantum systems. Our approach offers a unified viewpoint on quantum thermalization, measurement-induced disturbance, and the degradation of quantum advantage in practical devices, while also improving optimization strategies for current and near-term noisy quantum hardware. + oai:arXiv.org:2511.22350v2 quant-ph - hep-ph - Wed, 10 Dec 2025 00:00:00 -0500 + math-ph + math.MP + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Xiangjun Tan, Zhanning Wang + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Xiang Zhou - 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 + Data-Driven Learnability Transition of Measurement-Induced Entanglement + https://arxiv.org/abs/2512.01317 + arXiv:2512.01317v2 Announce Type: replace +Abstract: Measurement-induced entanglement (MIE) captures how local measurements generate long-range quantum correlations and drive dynamical phase transitions in many-body systems. Yet estimating MIE experimentally remains challenging: direct evaluation requires extensive post-selection over measurement outcomes, raising the question of whether MIE is accessible with only polynomial resources. We address this challenge by reframing MIE detection as a data-driven learning problem that assumes no prior knowledge of state preparation. Using measurement records alone, we train a neural network in a self-supervised manner to predict the uncertainty metric for MIE--the gap between upper and lower bounds of the average post-measurement bipartite entanglement. Applied to random circuits with one-dimensional all-to-all connectivity and two-dimensional nearest-neighbor coupling, our method reveals a learnability transition with increasing circuit depth: below a threshold, the uncertainty is small and decreases with polynomial measurement data and model parameters, while above it the uncertainty remains large despite increasing resources. We further verify this transition experimentally on current noisy quantum devices, demonstrating its robustness to realistic noise. These results highlight the power of data-driven approaches for learning MIE and delineate the practical limits of its classical learnability. + oai:arXiv.org:2512.01317v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.dis-nn + cs.AI + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/7gg9-klc4 - Physical Review A 112,062418 (2025) - Yu Luo, Zhihua Guo, Fanxu Meng, Chen-Ming Bai + Dongheng Qian, Jing Wang - 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 + Quantum hypergraph states: a review + https://arxiv.org/abs/2512.02955 + arXiv:2512.02955v2 Announce Type: replace +Abstract: Quantum hypergraph states emerged in the literature as a generalization of graph states, and since then, considerable progress has been made toward implementing this class of genuine multipartite entangled states for quantum information and computation. Here, we review the definition of hypergraph states and their main applications so far, both in discrete-variable and continuous-variable quantum information. + oai:arXiv.org:2512.02955v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/9fj9-x3v6 - Physical Review A 112,062408 (2025) - Jinghang Zhang, Yu Luo + Vin\'icius Salem - 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 + F2: Offline Reinforcement Learning for Hamiltonian Simulation via Free-Fermionic Subroutine Compilation + https://arxiv.org/abs/2512.08023 + arXiv:2512.08023v2 Announce Type: replace +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 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:2512.08023v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + cond-mat.mtrl-sci + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sergio Giardino + http://creativecommons.org/licenses/by/4.0/ + Ethan Decker, Christopher Watson, Junyu Zhou, Yuhao Liu, Chenxu Liu, Ang Li, Gushu Li, Samuel Stein - 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 + High-OAM Deep Ultraviolet Twisted Light Generation for RF-Photoinjector Applications + https://arxiv.org/abs/2512.08442 + arXiv:2512.08442v2 Announce Type: replace +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:2512.08442v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + physics.acc-ph + physics.optics + Thu, 11 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Fumin Wang + 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 - 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 + Quantum Brownian Motion as a Classical Stochastic Process in Phase Space + https://arxiv.org/abs/2512.08641 + arXiv:2512.08641v2 Announce Type: replace +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:2512.08641v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Damian Rovara, Lukas Burgholzer, Robert Wille + http://creativecommons.org/licenses/by/4.0/ + Dmitriy Kondaurov, Evgeny Polyakov - 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 + A Unified Framework for Optimizing Uniformly Controlled Structures in Quantum Circuits + https://arxiv.org/abs/2512.08675 + arXiv:2512.08675v2 Announce Type: replace +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 confirm reductions in depth and size, which 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:2512.08675v2 quant-ph - cond-mat.stat-mech - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ching-Tai Huang, Yu-Cheng Lin, Ferenc Igloi + Chengzhuo Xu, Xiao Chen, Xi Li, Zhihao Liu, Zhigang Li - A contextual advantage for conclusive exclusion: repurposing the Pusey-Barrett-Rudolph construction - https://arxiv.org/abs/2512.04173 - 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:2512.04173v3 + Autonomous multi-ion optical clock with on-chip integrated photonic light delivery + https://arxiv.org/abs/2512.08921 + arXiv:2512.08921v2 Announce Type: replace +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 $^{171}\textrm{Yb}^{+}$ 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:2512.08921v2 quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 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 + http://creativecommons.org/licenses/by/4.0/ + Tharon D. Morrison, Joonhyuk Kwon, Matthew A. Delaney, David R. Leibrandt, Daniel Stick, Hayden J. McGuinness - 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 + Equiangular lines via matrix projection + https://arxiv.org/abs/2110.15842 + arXiv:2110.15842v5 Announce Type: replace-cross +Abstract: In 1973, Lemmens and Seidel posed the problem of determining the maximum number of equiangular lines in $\mathbb{R}^r$ with angle $\arccos(\alpha)$ and gave a partial answer in the regime $r \leq 1/\alpha^2 - 2$. At the other extreme where $r$ is at least exponential in $1/\alpha$, recent breakthroughs have led to an almost complete resolution of this problem. In this paper, we introduce a new method for obtaining upper bounds which unifies and improves upon previous approaches, thereby yielding bounds which bridge the gap between the aforementioned regimes and are best possible either exactly or up to a small multiplicative constant. Our approach relies on orthogonal projection of matrices with respect to the Frobenius inner product and as a byproduct, it yields the first extension of the Alon-Boppana theorem to dense graphs, with equality for strongly regular graphs corresponding to $\binom{r+1}{2}$ equiangular lines in $\mathbb{R}^r$. Applications of our method in the complex setting will be discussed as well. + oai:arXiv.org:2110.15842v5 + math.CO + cs.IT + math.IT + math.MG quant-ph - 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 + Thu, 11 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Igor Balla - 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 + Emergent metric from wavelet-transformed quantum field theory + https://arxiv.org/abs/2504.06698 + arXiv:2504.06698v3 Announce Type: replace-cross +Abstract: We introduce a method of reverse holography by which a bulk metric is shown to arise from locally computable multiscale correlations of a boundary quantum field theory (QFT). The metric is obtained from the Petz-R\'enyi mutual information defined with input correlations computed from the continuous wavelet transform. The method is applicable to a variety of boundary QFTs that need not be conformal field theories (CFTs). For thermal free scalar and Dirac field theories the resulting bulk metric is that of (asymmetrically) warped anti-de Sitter (AdS) space. For massless, ground state CFTs the geometry simply reduces to AdS space. We show that certain parameters of the geometry can be tuned by changing the shape of the wavelet function. + oai:arXiv.org:2504.06698v3 + hep-th quant-ph - cond-mat.mes-hall - Wed, 10 Dec 2025 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daryoosh Vashaee, Jahanfar Abouie + Thu, 11 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + \v{S}imon Vedl, Daniel J. George, Fil Simovic, Dominic G. Lewis, Nicholas Funai, Achim Kempf, Nicolas C. Menicucci, Gavin K. Brennen - 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 + From spin to pseudospin symmetry: The origin of magic numbers in nuclear structure + https://arxiv.org/abs/2504.09148 + arXiv:2504.09148v2 Announce Type: replace-cross +Abstract: Magic numbers lie at the heart of nuclear structure, reflecting enhanced stability in nuclei with closed shells. While the emergence of magic numbers beyond 20 is commonly attributed to strong spin-orbit coupling, the microscopic origin of the spin-orbit potential remains elusive, owing to its dependence on the resolution scale and renormalization scheme of nuclear forces. Here, we investigate the evolution of shell structure with varying momentum resolution in nuclear interactions derived from chiral effective field theory, using the similarity renormalization group to link different scales. We uncover a novel transition from spin symmetry to pseudospin symmetry as the resolution scale decreases, during which magic numbers emerge naturally. A similar pattern is found in calculations using relativistic one-boson-exchange potentials, underscoring the robustness of the phenomenon. This establishes a direct connection between realistic nuclear forces with a high resolution scale and effective nuclear forces at coarse-grained scales, offering a first-principles explanation for the origin of magic numbers and pseudospin symmetry in nuclear shell structure, and new insights into the structure of exotic nuclei far from stability. + oai:arXiv.org:2504.09148v2 + nucl-th + nucl-ex quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jisang Seo, Hyunwoo Choi, Thomas E Roth, Jie Zhu, Weng C Chew, Dong-Yeop Na + 10.1103/8lzc-j1lx + C. R. Ding, C. C. Wang, J. M. Yao, H. Hergert, H. Z. Liang, S. Bogner - 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 + Thermal modifications of mesons and energy-energy correlators from real-time simulations of a $U(1)$ lattice gauge theory + https://arxiv.org/abs/2507.16890 + arXiv:2507.16890v2 Announce Type: replace-cross +Abstract: We investigate thermal properties of a $U(1)$ lattice gauge theory in $1+1$-dimensions through real-time simulations. We extract the spectral functions directly coupling to the pseudoscalar and scalar mesons, demonstrating the thermal modifications of these states with increasing temperatures. Introducing the notion of energy-flow operators, we quantify the temporal build-up of correlations in the energy flows across the lattice. We demonstrate that energy-energy correlators fail to factorize to products of energy flows, both in the vacuum and at nonzero-temperature, indicating the presence of non-trivial correlations in the quantum states. Our results constitute a first real-time \textit{ab-initio} study of bound state thermal broadening and finite temperature energy-flow correlations in a gauge theory, providing a benchmark for future studies of hadronic matter under extreme conditions. + oai:arXiv.org:2507.16890v2 + hep-ph + hep-lat quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/3nfx-fkfg - Phys. Rev. B 112, 224415 (2025) - Tingyu Gao, Niklas Tausendpfund, Erik L. Weerda, Jan Naumann, Matteo Rizzi, David F. Mross + 10.1103/x3sn-vq11 + Phys. Rev. D 112, 114505 (2025) + Jo\~ao Barata, David Frenklakh, Swagato Mukherjee - 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 + Quantum interferometry in external gravitational fields + https://arxiv.org/abs/2507.21808 + arXiv:2507.21808v3 Announce Type: replace-cross +Abstract: Current models of quantum interference experiments in external gravitational fields lack a common framework: while matter-wave interferometers are commonly described using the Schr\"odinger equation with a Newtonian potential, gravitational effects in quantum optics are modeled using either post-Newtonian metrics or highly symmetric exact solutions to Einstein's field equations such as those of Schwarzschild and Kerr. To coherently describe both kinds of experiments, this paper develops a unified framework for modeling quantum interferometers in general stationary space-times. This model provides a rigorous description and coherent interpretation of the effects of classical gravity on quantum probes. + oai:arXiv.org:2507.21808v3 + gr-qc quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross 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 + 10.1103/8dsx-jt6b + Phys. Rev. A 112, 062211 (2025) + Thomas B. Mieling, Thomas Morling, Christopher Hilweg, Philip Walther - 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 + Nitrogen-Vacancy Emission from Nanodiamond: Size, Depth, and Surroundings + https://arxiv.org/abs/2508.08565 + arXiv:2508.08565v3 Announce Type: replace-cross +Abstract: The negatively charged nitrogen-vacancy (NV) center in diamond is a leading solid-state quantum emitter, offering spin-photon interfaces over a wide temperature range with applications from electromagnetic sensing to bioimaging. While NV centers in bulk diamond are well understood, embedding them in nanodiamond (ND) introduces complexities from size, NV location, and NV polarizations. NVs in ND show altered fluorescence properties including longer lifetimes, lower quantum efficiency, and higher sensitivity to dielectric surroundings, which arise from radiative suppression, surface-induced non-radiative decay, and escape inefficiency at the diamond-background interface. Prior models typically addressed isolated aspects, such as dielectric contrast or surface quenching, without integrating full quantum-optical NV behavior with classical electrodynamics. We present a hybrid framework coupling rigorous electromagnetic simulations with a quantum-optical NV model including phonon sideband dynamics. NV emission is found to depend strongly on ND size, NV position, and surrounding refractive index. Our results explain observations such as shallow NVs in water-coated ND appearing brighter than deeper ones in air. This integrated model provides a unified framework for realistic NV in ND emission scenarios and informs the design of efficient NV-based sensors and quantum devices, advancing understanding of quantum emitter photophysics in nanoscale crystals. + oai:arXiv.org:2508.08565v3 + physics.optics + cond-mat.mes-hall quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Antoine Soulas + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1002/andp.202500367 + Annalen der Physik,2025;0:e00367 + Harini Hapuarachchi, Francesco Campaioli, Jared H Cole, Andrew D Greentree, Qiang Sun 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 + arXiv:2508.15121v3 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 + oai:arXiv.org:2508.15121v3 hep-th math-ph math.MP quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ A. J. D. Farias Junior, Andrea Erdas, Herondy F. Santana Mota - 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 - cond-mat.stat-mech - hep-th + A Continuous Energy Ising Machine Leveraging Difference-of-Convex Programming + https://arxiv.org/abs/2509.01928 + arXiv:2509.01928v2 Announce Type: replace-cross +Abstract: Many combinatorial optimization problems can be reformulated as finding the ground state of the Ising model. Existing Ising solvers are mostly inspired by simulated annealing. Although annealing techniques offer scalability, they lack convergence guarantees and are sensitive to the cooling schedule. We propose solving the Ising problem by relaxing the binary spins to continuous variables and introducing an attraction potential that steers the solution toward binary spin configurations. A key property of this potential is that its combination with the Ising energy produces a Hamiltonian that can be written as a difference of convex polynomials. This enables us to design efficient iterative algorithms that require a single matrix-vector multiplication per iteration and provide convergence guarantees. We implement our Ising solver on a wide range of GPU platforms, from edge devices to high-performance computing clusters, and demonstrate that it consistently outperforms existing solvers across problem sizes ranging from small ($10^3$ spins) to ultra-large ($10^8$ spins). + oai:arXiv.org:2509.01928v2 + cs.DC + math-ph + math.MP + math.OC quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Meng-Yuan Li, Peng Ye + Debraj Banerjee, Santanu Mahapatra, Kunal Narayan Chaudhury - 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 + Photonic Exceptional Points in Holography and QCD + https://arxiv.org/abs/2510.15518 + arXiv:2510.15518v4 Announce Type: replace-cross +Abstract: In this work, based on an analogy of holographic confining geometries and using complexified fields, we build the holographic toy model of third order photonic exceptional points (EPs) of ternary coupled microrings with gain and loss, which makes an open, non-Hermitian quantum system. In our model, we discuss the Ferrell-Glover-Tinkham sum rule for various combinations of gain and loss systems, and numerically find the behavior of spectra which matches with the experiments. We also discuss the inhomogeneous case of a holographic lattice for three-site photonic EPs. Additionally, in our holographic model, we numerically find the behavior of phase rigidity and the Petermann factor around EPs versus various parameters of the model. We also discuss the connections between recent developments in complexified, time-dependent entanglement entropy and EPs, and finally, we connect EPs and the $\theta$-vacuum of QCD through topological structures, partition functions, and winding numbers, and find a second-order EP in a perturbed $\theta$-vacuum model. + oai:arXiv.org:2510.15518v4 + hep-th quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Ethan Abraham + Mahdis Ghodrati - 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 - math.MP + Group Representations of Lorentz Transformations Extended to Superluminal Observers + https://arxiv.org/abs/2510.25385 + arXiv:2510.25385v3 Announce Type: replace-cross +Abstract: We construct an extension of the proper orthochronous Lorentz group that includes space-time transformations for observers moving with superluminal relative velocities in arbitrary direction. This extension is generated by a realization of the Klein four group depending on polar and azimuthal angles identifying a spatial direction and is obtained with matrices representing infinite velocity limits of superluminal Lorentz boosts. The resulting group has the same identity component of the whole Lorentz group O(3,1) but involutive operators corresponding to an infinite speed boost and its negative in place of parity and time reversal. Different spatial directions in the definition of Klein group realization give rise to equivalent group extensions. We then define the extended Poincare group including translations and classify its unitary irreducible representations (UIRs). The resulting UIRs are induced from Wigner's UIRs of standard Poincare group and depend on the action of the extended Lorentz group defined on momentum space. UIRs corresponding to non lightlike orbits restrict to the ordinary Poincare subgroup as a multiplicity one direct sum of a massive forward, a massive backward and a tachyonic Wigner UIR while for lightlike orbits as two inequivalent direct sum representations combiningh linearly a forward and backward massless Wigner UIR. We then derive wave equations corresponding to solutions of the Casimir eigenvalue problem of Poincare algebra obtained differentiating the above representations. This set of equations contains all the wave equations known to date in quantum field theory together with new wave equations describing tachyonic behaviour and a new class of massless representations. We finally show that tachyonic wave functions provide a relevant representation theoretic tool for interpretation of parity violation phenomena in quantum field theory + oai:arXiv.org:2510.25385v3 + hep-th quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - Stefan Teufel, Marius Wesle, Tom Wessel + http://creativecommons.org/publicdomain/zero/1.0/ + Marco Zaopo - 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 + Quantum-coherent optical isolation and circulation using frequency conversion on a chip + https://arxiv.org/abs/2511.00570 + arXiv:2511.00570v2 Announce Type: replace-cross +Abstract: Breaking optical reciprocity enables new regimes of light--matter interaction with broad implications for fundamental physics and emerging quantum technologies. Although various approaches have been explored to achieve optical nonreciprocity, realizing it at the single-photon level has remained a major challenge. Here, we demonstrate nonmagnetic optical nonreciprocity -- including both isolation and circulation -- in the quantum regime, enabled by efficient and noiseless all-optical frequency conversion on an integrated III-V photonic chip. Our device preserves the quantum coherence and entanglement of the input photons while delivering exceptional performance parameters, including a high extinction ratio of 34 dB, low insertion loss of 0.8 dB, broad bandwidth of 44 GHz, high operational fidelity of 97%, and widely tunable operation wavelength. This realization of quantum optical nonreciprocity in a scalable photonic platform opens a pathway toward directional quantum communication and noise-resilient quantum networks. + oai:arXiv.org:2511.00570v2 + physics.optics quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Philip Osterholz, Fabio Bensch, Shuanghong Tang, Silpa Baburaj Sheela, Igor Lesanovsky, Christian Gro{\ss} + Jierui Hu, Hao Yuan, Joshua Akin, Shanhui Fan, Kejie Fang - 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 + Inductive van der Waals Force between Two Quantum Loops + https://arxiv.org/abs/2512.01263 + arXiv:2512.01263v2 Announce Type: replace-cross +Abstract: We study the van der Waals-London force, which is typically associated with fluctuating dipoles in atoms, in a mesoscopic circuit consisting of two inductively coupled superconducting loops. We investigate the ``inductive" van der Waals-London interaction using both semiclassical and quantum electrodynamic (QED) approaches. The semiclassical model predicts a repulsive interaction due to anticorrelated current fluctuations. In contrast, the QED framework, which incorporates virtual photon exchange, reveals a predominantly attractive force. A key contribution comes from a state-independent two-photon exchange, which is absent in the semiclassical description and undetectable by spectroscopy. Our study introduces a new experimental platform for measuring the van der Waals force between individual artificial atoms via controlled mesoscopic circuits. + oai:arXiv.org:2512.01263v2 + cond-mat.mes-hall + physics.atom-ph quant-ph - Wed, 10 Dec 2025 00:00:00 -0500 + Thu, 11 Dec 2025 00:00:00 -0500 replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jia-Hui Zhang, Wen-Yuan Wang, Fu-Quan Dou + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Kicheon Kang + + + Real-Time Dynamics in Two Dimensions with Tensor Network States via Time-Dependent Variational Monte Carlo + https://arxiv.org/abs/2512.06768 + arXiv:2512.06768v2 Announce Type: replace-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:2512.06768v2 + cond-mat.str-el + cond-mat.stat-mech + quant-ph + Thu, 11 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Yantao Wu