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" @@ -7,12 +7,1273 @@ http://www.rssboard.org/rss-specification en-us - Sat, 24 Jan 2026 05:00:00 +0000 + Mon, 02 Feb 2026 05:00:07 +0000 rss-help@arxiv.org - Sat, 24 Jan 2026 00:00:00 -0500 + Mon, 02 Feb 2026 00:00:00 -0500 - Saturday Sunday + Saturday + + Practical Evaluation of Quantum Kernel Methods for Radar Micro-Doppler Classification on Noisy Intermediate-Scale Quantum (NISQ) Hardware + https://arxiv.org/abs/2601.22194 + arXiv:2601.22194v1 Announce Type: new +Abstract: This paper examines the application of a Quantum Support Vector Machine (QSVM) for radarbased aerial target classification using micro-Doppler signatures. Classical features are extracted and reduced via Principal Component Analysis (PCA) to enable efficient quantum encoding. The reduced feature vectors are embedded into a quantum kernel-induced feature space using a fully entangled ZZFeatureMap and classified using a kernel based QSVM. Performance is first evaluated on a quantum simulator and subsequently validated on NISQ-era superconducting quantum hardware, specifically the IBM Torino (133-qubit) and IBM Fez (156-qubit) processors. Experimental results demonstrate that the QSVM achieves competitive classification performance relative to classical SVM baselines while operating on substantially reduced feature dimensionality. Hardware experiments reveal the impact of noise and decoherence and measurement shot count on quantum kernel estimation, and further show improved stability and fidelity on newer Heron r2 architecture. This study provides a systematic comparison between simulator-based and hardware-based QSVM implementations and highlights both the feasibility and current limitations of deploying quantum kernel methods for practical radar signal classification tasks. + oai:arXiv.org:2601.22194v1 + quant-ph + cs.AI + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Vikas Agnihotri, Jasleen Kaur, Sarvagya Kaushik + + + Probing Entanglement and Symmetries in Random States Using a Superconducting Quantum Processor + https://arxiv.org/abs/2601.22224 + arXiv:2601.22224v1 Announce Type: new +Abstract: Quantum many-body systems display an extraordinary degree of complexity, yet many of their features are universal: they depend not on microscopic details, but on a few fundamental physical aspects such as symmetries. A central challenge is to distill these universal characteristics from model-specific ones. Random quantum states sampled from a uniform distribution, the Haar measure, provide a powerful framework for capturing this typicality. Here, we experimentally study the entanglement and symmetries of random many-body quantum states generated by evolving simple product states under ergodic Floquet models. We find excellent agreement with the predictions from the Haar-random state ensemble. First, we measure the R\'enyi-2 entanglement entropy as a function of the subsystem size, observing the Page curve. Second, we probe the subsystem symmetries using entanglement asymmetry. Finally, we measure the moments of partially transposed reduced density matrices obtained by tracing out part of the system in the generated ensembles, thereby revealing distinct entanglement phases. Our results offer an experimental perspective on the typical entanglement and symmetries of many-body quantum systems. + oai:arXiv.org:2601.22224v1 + quant-ph + cond-mat.stat-mech + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Jia-Nan Yang, Lata Kh Joshi, Filiberto Ares, Yihang Han, Pengfei Zhang, Pasquale Calabrese + + + The Photonic Foundation of Temperature: Mechanisms of Thermal Equilibrium and Entropy Production + https://arxiv.org/abs/2601.22247 + arXiv:2601.22247v1 Announce Type: new +Abstract: I examine the physical foundations of temperature and thermal equilibrium by identifying photons as the fundamental agents that establish and maintain the characteristic energy scale $E_c = k_B T$ in ordinary matter. While classical thermodynamics successfully describes equilibrium phenomenologically, the realization of thermal distributions requires concrete microscopic mechanisms provided by quantum electrodynamics. We derive the Boltzmann distribution from a minimal differential scaling postulate and show that sustaining thermal equilibrium demands continuous photon exchange with average energy $\langle h\nu \rangle = 2.701\,E_c$, quantifying the energetic throughput necessary to counter radiative losses. Entropy production is shown to arise naturally from inelastic photon scattering that converts high-energy photons into many lower-energy quanta, thereby increasing accessible microstates and driving irreversible evolution toward equilibrium. We establish physical criteria distinguishing genuine thermal equilibrium from purely formal temperature assignments and demonstrate that the classical notion of an infinite thermal reservoir emerges as an effective idealization within a hierarchy of dynamically maintained photon baths. This photonic framework complements phenomenological thermodynamics by providing its microscopic foundation and clarifies the physical meaning of temperature as an emergent collective property of photon-mediated energy exchange. + oai:arXiv.org:2601.22247v1 + quant-ph + cond-mat.stat-mech + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + David Vaknin + + + Entanglement and discord classification via deep learning + https://arxiv.org/abs/2601.22253 + arXiv:2601.22253v1 Announce Type: new +Abstract: In this work, we propose a deep learning-based approach for quantum entanglement and discord classification using convolutional autoencoders. We train models to distinguish entangled from separable bipartite states for $d \times d$ systems with local dimension $d$ ranging from two to seven, which enables identification of bound and free entanglement. Through extensive numerical simulations across various quantum state families, we demonstrate that our model achieves high classification accuracy. Furthermore, we leverage the learned representations to generate samples of bound entangled states, the rarest form of entanglement and notoriously difficult to construct analytically. We separately train the same convolutional autoencoders architecture for detecting the presence of quantum discord and show that the model also exhibits high accuracy while requiring significantly less training time. + oai:arXiv.org:2601.22253v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Katherine Mu\~noz-Mellado, Daniel Uzc\'ategui-Contreras, Antonio Guerra, Aldo Delgado, Dardo Goyeneche + + + Some properties of coherent states with singular complex matrix argument + https://arxiv.org/abs/2601.22258 + arXiv:2601.22258v1 Announce Type: new +Abstract: In the paper our aim was to study the properties of a new version of coherent states whose argument is a linear combination of two special singular square 2 x 2 matrix, having a single nonzero element, equal to 1, and two labeling complex variables as developing coefficients. We have shown that this new version of coherent states satisfies all the conditions imposed on coherent states, both of pure, as well as the mixed (thermal) states characterized by the density operator. As applications, we examined the connection between these coherent states and the notions of qubits and von Neuman entropy. + oai:arXiv.org:2601.22258v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/publicdomain/zero/1.0/ + Du\v{s}an Popov + + + Three-dimensional squeezing of optically levitated nanospheres + https://arxiv.org/abs/2601.22283 + arXiv:2601.22283v1 Announce Type: new +Abstract: We propose a protocol to measure impulses beyond the standard quantum limit. The protocol reduces noise in all three spatial dimensions and consists of squeezing a mechanical system's state via a series of jumps in the frequency of the harmonic potential. We quantify how decoherence in a realistic system of an optically levitated, dielectric nanoparticle limits the ultimate sensitivity. We predict that $\sim$10 dB of squeezing is achievable with current technology, enabling quantum-enhanced detection of weak impulses. + oai:arXiv.org:2601.22283v1 + quant-ph + hep-ex + physics.ins-det + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Giacomo Marocco, David C. Moore, Daniel Carney + + + Efficient learning of logical noise from syndrome data + https://arxiv.org/abs/2601.22286 + arXiv:2601.22286v1 Announce Type: new +Abstract: Characterizing errors in quantum circuits is essential for device calibration, yet detecting rare error events requires a large number of samples. This challenge is particularly severe in calibrating fault-tolerant, error-corrected circuits, where logical error probabilities are suppressed to higher order relative to physical noise and are therefore difficult to calibrate through direct logical measurements. Recently, Wagner et al. [PRL 130, 200601 (2023)] showed that, for phenomenological Pauli noise models, the logical channel can instead be inferred from syndrome measurement data generated during error correction. Here, we extend this framework to realistic circuit-level noise models. From a unified code-theoretic perspective and spacetime code formalism, we derive necessary and sufficient conditions for learning the logical channel from syndrome data alone and explicitly characterize the learnable degrees of freedom of circuit-level Pauli faults. Using Fourier analysis and compressed sensing, we develop efficient estimators with provable guarantees on sample complexity and computational cost. We further present an end-to-end protocol and demonstrate its performance on several syndrome-extraction circuits, achieving orders-of-magnitude sample-complexity savings over direct logical benchmarking. Our results establish syndrome-based learning as a practical approach to characterizing the logical channel in fault-tolerant quantum devices. + oai:arXiv.org:2601.22286v1 + quant-ph + math-ph + math.MP + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Han Zheng, Chia-Tung Chu, Senrui Chen, Argyris Giannisis Manes, Su-un Lee, Sisi Zhou, Liang Jiang + + + Local-oscillator-agnostic squeezing detection + https://arxiv.org/abs/2601.22291 + arXiv:2601.22291v1 Announce Type: new +Abstract: We address the problem of measuring nonclassicality in continuous-variable bosonic systems without having access to a known reference signal. To this end, we construct broader classes of criteria for nonclassicality which allow us to investigate quantum phenomena regardless of the quantumness of selected subsystems. Such witnesses are based on the notion of partial normal ordering. This approach is applied to balanced homodyne detection using arbitrary, potentially nonclassical local oscillator states, yet only revealing the probed signal's quantumness. Our framework is compared to standard techniques, and the robustness and advanced sensitivity of our approach is shown. Therefore, a widely applicable framework, well-suited for applications in quantum metrology and quantum information, is derived to assess the quantum features of a photonic system when a well-defined coherent laser as a reference state is not available in the physical domain under study. + oai:arXiv.org:2601.22291v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Suchitra Krishnaswamy, Dhrithi Maria, Laura Ares, Lorenzo M. Procopio, Tim J. Bartley, Jan Sperling + + + Quantum bootstrap product codes + https://arxiv.org/abs/2601.22363 + arXiv:2601.22363v1 Announce Type: new +Abstract: Product constructions constitute a powerful method for generating quantum CSS codes, yielding celebrated examples such as toric codes and asymptotically good low-density parity check (LDPC) codes. Since a CSS code is fully described by a chain complex, existing product formalisms are predominantly homological, defined via the tensor product of the underlying chain complexes of input codes, thereby establishing a natural connection between quantum codes and topology. In this Letter, we introduce the \textit{quantum bootstrap product} (QBP), an approach that extends beyond this standard homological paradigm. Specifically, a QBP code is determined by solving a consistency condition termed the ``bootstrap equation''. We find that the QBP paradigm unifies a wide range of important codes, including general hypergraph product (HGP) codes of arbitrary dimensions and fracton codes typically represented by the X-cube code. Crucially, the solutions to the bootstrap equation yield chain complexes where the chain groups and associated boundary maps consist of multiple components. We term such structures \textit{fork complexes}. This structure elucidates the underlying topological structures of fracton codes, akin to foliated fracton order theories. Beyond conceptual insights, we demonstrate that the QBP paradigm can generate self-correcting quantum codes from input codes with constant energy barriers and surpass the code-rate upper bounds inherent to HGP codes. Our work thus substantially extends the scope of quantum product codes and provides a versatile framework for designing fault-tolerant quantum memories. + oai:arXiv.org:2601.22363v1 + quant-ph + cond-mat.str-el + math-ph + math.MP + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Meng-Yuan Li + + + Manjushri: A Tool for Equivalence Checking of Quantum Circuits + https://arxiv.org/abs/2601.22372 + arXiv:2601.22372v1 Announce Type: new +Abstract: Verifying whether two quantum circuits are equivalent is a central challenge in the compilation and optimization of quantum programs. We introduce \textsc{Manjushri}, a new automated framework for scalable quantum-circuit equivalence checking. \textsc{Manjushri} uses local projections as discriminative circuit fingerprints, implemented with weighted binary decision diagrams (WBDDs), yielding a compact and efficient symbolic representation of quantum behavior. We present an extensive experimental evaluation that, for random 1D Clifford+$T$ circuits, explores the trade-off between \textsc{Manjushri} and \textsc{ECMC}, a tool for equivalence checking based on a much different approach. \textsc{Manjushri} is much faster up to depth 30 (with the crossover point varying from 39--49, depending on the number of qubits and whether the input circuits are equivalent or inequivalent): when inputs are equivalent, \textsc{Manjushri} is about 10$\times$ faster (or more); when inputs are inequivalent, \textsc{Manjushri} is about 8$\times$ faster (or more). For both kinds of equivalence-checking outcomes, \textsc{ECMC}'s success rate out to depth 50 is impressive on 32- and 64-qubit circuits: on such circuits, \textsc{ECMC} is almost uniformly successful. However, \textsc{ECMC} struggled on 128-qubit circuits for some depths. \textsc{Manjushri} is almost uniformly successful out to about depth 38, before tailing off to about 75\% at depth 50 (falling to 0\% at depth 48 for 128-qubit circuits that are equivalent). These results establish that \textsc{Manjushri} is a practical and scalable solution for large-scale quantum-circuit verification, and would be the preferred choice unless clients need to check equivalence of circuits of depth $>$38. + oai:arXiv.org:2601.22372v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Xuan Du Trinh, Meghana Sistla, Nengkun Yu, Thomas Reps + + + Spectral Filtering for Learning Quantum Dynamics + https://arxiv.org/abs/2601.22400 + arXiv:2601.22400v1 Announce Type: new +Abstract: Learning high-dimensional quantum systems is a fundamental challenge that notoriously suffers from the curse of dimensionality. We formulate the task of predicting quantum evolution in the linear response regime as a specific instance of learning a Complex-Valued Linear Dynamical System (CLDS) with sector-bounded eigenvalues -- a setting that also encompasses modern Structured State Space Models (SSMs). While traditional system identification attempts to reconstruct full system matrices (incurring exponential cost in the Hilbert dimension), we propose Quantum Spectral Filtering, a method that shifts the goal to improper dynamic learning. Leveraging the optimal concentration properties of the Slepian basis, we prove that the learnability of such systems is governed strictly by an effective quantum dimension $k^*$, determined by the spectral bandwidth and memory horizon. This result establishes that complex-valued LDSs can be learned with sample and computational complexity independent of the ambient state dimension, provided their spectrum is bounded. + oai:arXiv.org:2601.22400v1 + quant-ph + cs.AI + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Elad Hazan, Annie Marsden + + + On the undecidability of quantum channel capacities + https://arxiv.org/abs/2601.22471 + arXiv:2601.22471v1 Announce Type: new +Abstract: An important distinction in our understanding of capacities of classical versus quantum channels is marked by the following question: is there an algorithm which can compute (or even efficiently compute) the capacity? While there is overwhelming evidence suggesting that quantum channel capacities may be uncomputable, a formal proof of any such statement is elusive. We initiate the study of the hardness of computing quantum channel capacities. We show that, for a general quantum channel, it is QMA-hard to compute its quantum capacity, and that the maximal-entanglement-assisted zero-error one-shot classical capacity is uncomputable. + oai:arXiv.org:2601.22471v1 + quant-ph + cs.CC + cs.IT + math.IT + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Archishna Bhattacharyya, Arthur Mehta, Yuming Zhao + + + Dicke States for Accelerated Two Two-Level Atoms + https://arxiv.org/abs/2601.22479 + arXiv:2601.22479v1 Announce Type: new +Abstract: We explore the formation of Dicke states. A system consisting of two two-level atoms located in the right Rindler wedge, has investigated to determine the conditions under which the superradiant or subradiant state can be formed. The dynamics of N two-level atoms forming symmetric state has also been analyzed and showed that the probability to excite any one atom of a collection of N atoms is related to the probability of exciting a single atom. We derive the analytical expression for the joint excitation probability which demonstrates the the interference effect. These findings provide new insights into the behavior of quantum systems in non-inertial frames and contribute to the broader understanding of relativistic quantum information theory. + oai:arXiv.org:2601.22479v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Muzzamal I. Shaukat, Charles A. Wallace, Anatoly A. Svidzinsky, Marlan O. Scully + + + Structural Conditions for Native CCZ Magic-State Fountains in qLDPC Codes + https://arxiv.org/abs/2601.22489 + arXiv:2601.22489v1 Announce Type: new +Abstract: Quantum low-density parity-check (qLDPC) codes promise constant-rate, linear-distance families with bounded-weight checks, and recent work has realized transversal or constant-depth non-Clifford gates on various (often non-LDPC) codes. However, no explicit \emph{qubit} qLDPC family is known that simultaneously has constant rate, linear distance, bounded stabilizer weight, and a native \emph{magic-state fountain} that prepares many non-Clifford resource states in constant depth. + We take a structural approach and identify coding-theoretic conditions under which a CSS qLDPC family necessarily supports a constant-depth $\CCZ$ magic-state fountain. The key ingredients are: (i) an algebraic notion of \emph{magic-friendly triples} of $X$-type logical operators, defined by pairwise orthogonality and a triple-overlap form controlling diagonal $\CCZ$ phases, and (ii) a 3-uniform hypergraph model of physical $\CCZ$ circuits combined with a packing lemma that turns large collections of such triples with bounded overlaps into bounded-degree hypergraphs. + Our main theorem shows that if a CSS code family on $n$ qubits admits $\Omega(n^{1+\gamma})$ magic-friendly triples whose supports have bounded per-qubit participation, then there exists a constant-depth circuit of physical $\CCZ$ gates implementing $\Omega(n^{\gamma})$ logical $\CCZ$ gates in parallel while preserving distance up to a constant factor. For asymptotically good qLDPC families such as quantum Tanner codes, this reduces the existence of a native $\CCZ$ magic-state fountain to a concrete combinatorial problem about counting and distributing magic-friendly triples in the logical $X$ space. + oai:arXiv.org:2601.22489v1 + quant-ph + cs.IT + math.IT + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Mohammad Rowshan + + + Quantum-Enhanced Sensing Enabled by Scrambling-Induced Genuine Multipartite Entanglement + https://arxiv.org/abs/2601.22503 + arXiv:2601.22503v1 Announce Type: new +Abstract: Quantum sensing leverages quantum resources to surpass the standard quantum limit, yet many existing protocols rely on the preparation of complex entangled states and Hamiltonian engineering, posing challenges for universality and scalability. Here, we report an experimental realization of a universal protocol, known as Butterfly Metrology, proposed in [arXiv:2411.12794], demonstrating a scrambling-based approach for quantum-enhanced sensing on a superconducting quantum processor. By exploiting many-body information scrambling, we observe quantum-enhanced sensitivity to an encoded phase beyond the standard quantum limit, with a scaling consistent with a factor-of-two of the Heisenberg limit for system sizes of up to 10 qubits. Importantly, we experimentally establish a connection between the enhanced sensitivity and the dynamics of the out-of-time-order correlator (OTOC), and show that the buildup of scrambling-induced genuine multipartite entanglement underlies the observed sensitivity enhancement. Our results demonstrate a scalable and practical approach for quantum-enhanced sensing in interacting many-body quantum systems. + oai:arXiv.org:2601.22503v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Guantian Hu, Wenxuan Zhang, Zhihua Chen, Liuzhu Zhong, Jingchao Zhao, Chilong Liu, Zixing Liu, Yue Xu, Yongchang Lin, Yougui Ri, Guixu Xie, Mingze Liu, Haolan Yuan, Yuxuan Zhou, Yu Zhang, Chang-Kang Hu, Song Liu, Dian Tan, Dapeng Yu + + + Analysis of self-thermalization dynamics in the Bose-Hubbard model by using the pseudoclassical approach + https://arxiv.org/abs/2601.22553 + arXiv:2601.22553v1 Announce Type: new +Abstract: We analyze the self-thermalization dynamics of the $M$-site Bose-Hubbard model in terms of the single-particle density matrix that is calculated by using the pseudoclassical approach. It is shown that a weak inter-particle interaction, which suffices to convert the integrable system of non-interacting bosons into a chaotic system, has a negligible effect on the thermal density matrix given by the Bose-Einstein distribution. This opens the door for equilibration where the two coupled Bose-Hubbard systems, which are initially in different thermal states, relax to the same thermal state. When we couple these two subsystems by using a lattice of the length $L\ll M$, we numerically calculate the quasi-stationary current of Bose particles across the lattice and show that its magnitude is consistent with the solution of the master equation for the boundary driven $L$-site Bose-Hubbard model. + oai:arXiv.org:2601.22553v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Andrey R. Kolovsky + + + Towards Sample Efficient Entanglement Classification for 3 and 4 Qubit Systems: A Tailored CNN-BiLSTM Approach + https://arxiv.org/abs/2601.22562 + arXiv:2601.22562v1 Announce Type: new +Abstract: Accurate classification of multipartite entanglement in high-dimensional quantum systems is crucial for advancing quantum communication and information processing. However, conventional methods are resource-intensive, and even many machine-learning-based approaches necessitate large training datasets, creating a significant experimental bottleneck for data acquisition. To address this challenge, we propose a hybrid neural network architecture integrating Convolutional and Bidirectional Long Short-Term Memory networks (CNN-BiLSTM). This design leverages CNNs for local feature extraction and BiLSTMs for sequential dependency modeling, enabling robust feature learning from minimal training data. We investigate two fusion paradigms: Architecture 1 (flattening-based) and Architecture 2 (dimensionality-transforming). When trained on only 100 samples, Architecture 2 maintains classification accuracies exceeding 90% for both 3-qubit and 4-qubit systems, demonstrating rapid loss convergence within tens of epochs. Under full-data conditions (400 000 samples), both architectures achieve accuracies above 99.97%. Comparative benchmarks reveal that our CNN-BiLSTM models, especially Architecture 2, consistently outperform standalone CNNs, BiLSTMs, and MLPs in low-data regimes, albeit with increased training time. These results demonstrates that the tailored CNN-BiLSTM fusion significantly alleviates experimental data acquisition burden, offering a practical pathway toward scalable entanglement verification in complex quantum systems. + oai:arXiv.org:2601.22562v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Qian Sun, Yuedong Sun, Yu Hu, Yihan Ma, Runqi Han, Nan Jiang + + + Two-parameter bipartite entanglement measure + https://arxiv.org/abs/2601.22568 + arXiv:2601.22568v1 Announce Type: new +Abstract: Entanglement concurrence is an important bipartite entanglement measure that has found wide applications in quantum technologies. In this work, inspired by unified entropy, we introduce a two-parameter family of entanglement measures, referred to as the unified $(q,s)$-concurrence. Both the standard entanglement concurrence and the recently proposed $q$-concurrence emerge as special cases within this family. By combining the positive partial transposition and realignment criteria, we derive an analytical lower bound for this measure for arbitrary bipartite mixed states, revealing a connection to strong separability criteria. Explicit expressions are obtained for the unified $(q,s)$-concurrence in the cases of isotropic and Werner states under the constraint $q>1$ and $qs\geq 1$. Furthermore, we explore the monogamy properties of the unified $(q,s)$-concurrence for $q\geq 2$, $0\leq s\leq 1$ and $1\leq qs\leq 3$, in qubit systems. In addition, we derive an entanglement polygon inequality for the unified $(q,s)$-concurrence with $q\geq 1$ and $qs\geq 1$, which manifests the relationship among all the marginal entanglements in any multipartite qudit system. + oai:arXiv.org:2601.22568v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Chen-Ming Bai, Yu Luo + + + Multipartite entanglement measures based on the thermodynamic framework + https://arxiv.org/abs/2601.22583 + arXiv:2601.22583v1 Announce Type: new +Abstract: In this work, we introduce a unified method to characterize and measure multipartite entanglement using the framework of thermodynamics. A family of the new entanglement measures is proposed: \textit{ergotropic-gap concentratable entanglement}. Furthermore, we establish that ergotropic-gap concentratable entanglement constitutes a well-defined entanglement measure within a specific parameter regime, satisfying key properties including continuity, majorization monotonicity and monogamy. We demonstrate the utility of this measure by showing it effectively distinguishes between multi-qubit Greenberger-Horne-Zeilinger states and W states. It also proves effective in detecting entanglement in specific classes of four-partite star quantum network states. + oai:arXiv.org:2601.22583v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/rg65-sh1f + Physical Review A 112, 032424 (2025) + Chen-Ming Bai, Yu Luo + + + Unconventional Distance Scaling of Casimir-Polder Force between Atomic Arrays + https://arxiv.org/abs/2601.22640 + arXiv:2601.22640v1 Announce Type: new +Abstract: Conventionally, dispersion forces mediated by quantum vacuum fluctuations are known to exhibit universal distance scalings, with retardation typically leading to a faster decay of the interaction. Here, we show that this expectation fails for intrinsically discrete systems. Using the microscopic scattering approach, we study the Casimir-Polder interaction between two atomic arrays, and uncover an unconventional distance scaling in which the force crosses over from a faster decay at short separations to a slower decay in the retarded regime. This behavior originates from the discrete lattice structure and can be consistently understood within the scattering picture. Extending our analysis to Rydberg atomic arrays, we predict an even stronger deviation from conventional scaling and propose an experimentally feasible scheme for direct measurement. Our results provide a new platform for exploring dispersion forces beyond the continuum limit. + oai:arXiv.org:2601.22640v1 + quant-ph + physics.atom-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Qihang Ye, Qihang Ye, Bing Miao, Lei Ying + + + A complex-linear reformulation of Hamilton--Jacobi theory and the emergence of quantum structure + https://arxiv.org/abs/2601.22697 + arXiv:2601.22697v1 Announce Type: new +Abstract: Classical mechanics admits multiple equivalent formulations, from Newton's equations to the variational Lagrange-Hamilton framework and the scalar Hamilton-Jacobi (HJ) theory. In the HJ formulation, classical ensembles evolve through the continuity equation for a real density $\rho = R^{2}$ coupled to Hamilton's principal function $S$. Here we develop a complementary formulation, the Hamilton-Jacobi-Schr\"odinger (HJS) theory, by embedding the pair $(R,S)$ into a single complex field. Starting from a completely general complex ansatz $\psi = f(R,S) e^{i g(R,S)}$, and imposing two minimal structural requirements, we obtain a unique map $\psi = R e^{iS/\kappa}$ together with a linear HJS equation whose $|\kappa| \to 0$ limit reproduces the HJ formulation exactly. Remarkably, when $\mathrm{Re}(\kappa)\neq 0$, essential features of quantum mechanics, including superposition, operator algebra, commutators, the Heisenberg uncertainty principle, Born's rule, and unitary evolution, arise naturally as consistency conditions. HJS thus provides a unified mathematical viewpoint in which classical and quantum dynamics appear as different limits of a single underlying structure. + oai:arXiv.org:2601.22697v1 + quant-ph + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yong Zhang + + + Orders of magnitude runtime reduction in quantum error mitigation + https://arxiv.org/abs/2601.22785 + arXiv:2601.22785v1 Announce Type: new +Abstract: Quantum error mitigation (QEM) infers noiseless expectation values by combining outcomes from intentionally modified, noisy variants of a target quantum circuit. Unlike quantum error correction, QEM requires no additional hardware resources and is therefore routinely employed in experiments on contemporary quantum processors. A central limitation of QEM is its substantial sampling overhead, which necessitates long execution times where device noise may drift, potentially compromising the reliability of standard mitigation protocols. QEM strategies based on agnostic noise amplification (ANA) are intrinsically resilient to such noise variations, but their sampling cost remains a major practical bottleneck. Here we introduce a mitigation framework that combines virtual noise scaling with a layered mitigation architecture, yielding orders of magnitude reduction in runtime overhead compared to conventional zero-noise extrapolation post-processing. The proposed approach is compatible with dynamic circuits and can be seamlessly integrated with error detection and quantum error correction schemes. In addition, it naturally extends to ANA-based mitigation of mid-circuit measurements and preparation errors. We validate our post-processing approach by applying it to previously reported experimental data, where we observe a substantial improvement in mitigation efficiency and accuracy. + oai:arXiv.org:2601.22785v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Raam Uzdin + + + Scattering of Squeezed Light by a Dielectric Slab + https://arxiv.org/abs/2601.22798 + arXiv:2601.22798v1 Announce Type: new +Abstract: We develop a quantum theory for the scattering of squeezed coherent light by a dissipative dielectric slab. Using the Green-function quantization approach, we derive the transformation of the field quadratures and show how dispersion, absorption, and multiple reflections distort the incident squeezing. We find that the slab can selectively attenuate or amplify quadrature noise depending on the slab parameters and provide expressions for the output power spectra. + oai:arXiv.org:2601.22798v1 + quant-ph + physics.optics + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + G. Pooseh + + + Steady-State Emission of Quantum-Correlated Light in the Telecom Band from a Single Atom + https://arxiv.org/abs/2601.22821 + arXiv:2601.22821v1 Announce Type: new +Abstract: We propose and investigate a scheme for the steady-state emission of quantum-correlated, telecom-band light from a single multilevel atom. By appropriately tuning the frequency of a pair of lasers, a two-photon transition is continually driven to an atomic excited state that emits photons at the desired wavelength. We show that resonantly coupling a cavity mode to the telecom transition can enhance the rate of emission while retaining the antibunched counting statistics that are characteristic of atomic light sources. We also explore coupling a second, independent cavity mode to the atom, which increases the telecom emission rate and introduces quantum correlations between the cavity modes. A model for the hyperfine structure of a single cesium atom is then described and numerically integrated to demonstrate the viability of implementing the scheme with a modern cavity QED system. + oai:arXiv.org:2601.22821v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Alex Elliott, Takao Aoki, Scott Parkins + + + Are Bell's conditions for local realism general enough? + https://arxiv.org/abs/2601.22833 + arXiv:2601.22833v1 Announce Type: new +Abstract: Bell conditions for local realism are critically revisited. In particular for optical experiments I criticize Bell's proposed response of detectors to signals as extremely idealized. More physical conditions are proposed, whence a realistic local model of an optical experiment is possible which violates the Clauser-Horne (Bell) inequality. The possibility rests on the existence of a coincidence-time loophole in the experiments. + oai:arXiv.org:2601.22833v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + 10.1140/epjp/s13360-025-07010-8 + Eur. Phys. J. Plus 140, 1098 (2025) + Emilio Santos + + + Dynamics of states of infinite quantum systems as a cornerstone of the second law of thermodynamics + https://arxiv.org/abs/2601.22863 + arXiv:2601.22863v1 Announce Type: new +Abstract: We improve on our version of the second law of thermodynamics as a deterministic theorem for quantum spin systems in two basic aspects. The first concerns the general statement of the second law: spontaneous changes in an adiabatically closed system will always be in the direction of increasing mean entropy, which rises to a maximal value. Two specific examples concern the transition from pure to mixed states in two different universality classes of dynamics in one dimension, one being the exponential model, the other the Dyson model, the dynamics of the latter exhibiting strong graphical evidence of quantum chaos, as a consequence of the results of Albert and Kiessling on the Cloitre function. + oai:arXiv.org:2601.22863v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Walter F. Wreszinski + + + Fast magic state preparation by gauging higher-form transversal gates in parallel + https://arxiv.org/abs/2601.22939 + arXiv:2601.22939v1 Announce Type: new +Abstract: Magic states are a foundational resource for universal quantum computation. To survive in a realistic noisy environment, magic states must be prepared fault-tolerantly and protected by a quantum error-correcting code. The recent discovery of highly efficient quantum low-density parity-check codes, together with efficient logic gates, lays the groundwork for low-overhead fault-tolerant quantum computation. This motivates the search for fast and parallel protocols for logical magic state preparation to enable universal quantum computation. Here, we introduce a fast code surgery procedure that performs a fault-tolerant measurement of many transversal logic gates in parallel. This is achieved by performing a generalized gauging measurement on a quantum code that supports a higher-form transversal gate. The time overhead of our procedure is constant, and the qubit overhead is linear. The procedure inherits fault-tolerance properties from the base code and the structure of the higher-form transversal gate. When applied to codes that support higher-form Clifford gates our procedure achieves fast and fault-tolerant preparation of many magic states in parallel. This motivates the search for good quantum low-density parity-check codes that support higher-form Clifford gates. + oai:arXiv.org:2601.22939v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Dominic J. Williamson + + + High-resolution tunable frequency beamsplitter enabled by an integrated silicon pulse shaper + https://arxiv.org/abs/2601.23028 + arXiv:2601.23028v1 Announce Type: new +Abstract: We demonstrate high-fidelity, tunable, and ultrafine-resolution on-chip frequency beamsplitters using a quantum frequency processor based on an integrated pulse shaper with six spectral channels. Near-ideal Hadamard gate performance is achieved, with fidelity F > 0.9995 and modified success probability P > 0.9621 maintained across frequency spacings from 2-5 GHz and down to as few as four spectral pulse shaper channels. The system's support of frequency spacings as narrow as 2 GHz significantly surpasses prior bulk demonstrations and enables arbitrary splitting ratios via spectral phase or modulation index control. These results establish a scalable and resource-efficient platform for integrated frequency-bin quantum photonics, opening new directions in quantum information processing, including densely parallel single-qubit operations and multidimensional gate implementations. + oai:arXiv.org:2601.23028v1 + quant-ph + physics.optics + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Chen-You Su, Kaiyi Wu, Lucas M. Cohen, Saleha Fatema, Navin B. Lingaraju, Hsuan-Hao Lu, Andrew M. Weiner, Joseph M. Lukens, Jason D. McKinney + + + Dicke superposition probes for noise-resilient Heisenberg and super-Heisenberg Metrology + https://arxiv.org/abs/2601.23043 + arXiv:2601.23043v1 Announce Type: new +Abstract: Phase sensing with entangled multiqubit states in the presence of noise is a central theme of modern quantum metrology. The present work investigates Dicke state superposition probes for quantum phase sensing under parameter encoding generated by one- and two-body interaction Hamiltonians. A class of N-qubit Dicke superposition states that exhibit near-Heisenberg scaling, of the quantum Fisher information, while maintaining significantly enhanced robustness to dephasing noise compared to GHZ, W-superposition, and balanced Dicke states, under unitary encodings generated by one-body interaction Hamiltonians are identified. For two-body interactions, Dicke superposition probes optimizing the quantum Fisher information are identified, and their performance under phase-damping, amplitude-damping, and global depolarizing noise is explored. Within this family, certain Dicke superpositions are found to combine super-Heisenberg scaling with improved resilience to phase damping relative to Fisher information optimal probes. These results establish tailored near-optimal Dicke-state superposition probes as versatile and noise-resilient resources for Heisenberg and super-Heisenberg quantum phase sensing governed by one- and two-body interactions. + oai:arXiv.org:2601.23043v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Sudha, B. N. Karthik, K. S. Akhilesh, A. R. Usha Devi + + + Scalable Memory Sharing in Photonic Quantum Memristors for Reservoir Computing + https://arxiv.org/abs/2601.23044 + arXiv:2601.23044v1 Announce Type: new +Abstract: Although photons are robust, room-temperature carriers well suited to quantum machine learning, the absence of photon-photon interactions hinder the realization of memory functionalities that are critical for capturing long-range context. Recently, measurement-based implementations of photonic quantum memristors (PQMRs) have enabled tunable non-Markovian responses. However, their memory remains confined to local elements, in contrast to biological or artificial networks where memory is shared across the system. Here, we propose a scalable PQMR network that enables measurement-based memory sharing. Each memristive node updates its internal state using the history of its own and neighbouring quantum states, thereby realizing distributed memory. By modelling each node as a photonic quantum memtransistor, we demonstrate pronounced enhancements in both classical and quantum hysteresis at the device level, as well as enhanced network-level quantum hysteresis. Implemented as a quantum reservoir, the architecture achieves improved Fashion-MNIST classification accuracy and confidence via increased data separability. Our approach paves the way toward high-capacity quantum machine learning using memristive devices compatible with linear-optical quantum computing. + oai:arXiv.org:2601.23044v1 + quant-ph + physics.optics + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Chaehyeon Lim, Hyungchul Park, Beomjoon Chae, Jeonghun Kwak, Soo-Yeon Lee, Namkyoo Park, Sunkyu Yu + + + Margin-Based Generalisation Bounds for Quantum Kernel Methods under Local Depolarising Noise + https://arxiv.org/abs/2601.23084 + arXiv:2601.23084v1 Announce Type: new +Abstract: Generalisation refers to the ability of a machine learning (ML) model to successfully apply patterns learned from training data to new, unseen data. Quantum devices in the current Noisy Intermediate-Scale Quantum (NISQ) era are inherently affected by noise, which degrades generalisation performance. In this work, we derive upper and lower margin-based generalisation bounds for Quantum Kernel-Assisted Support Vector Machines (QSVMs) under local depolarising noise. These theoretical bounds characterise noise-induced margin decay and are validated via numerical simulations across multiple datasets, as well as experiments on real quantum hardware. We further justify the focus on margin-based measures by empirically establishing margins as a reliable indicator of generalisation performance for QSVMs. Additionally, we motivate the study of local depolarising noise by presenting empirical evidence demonstrating that the commonly used global depolarising noise model is overly optimistic and fails to accurately capture the degradation of generalisation performance observed in the NISQ era. + oai:arXiv.org:2601.23084v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Saarisha Govender, Ilya Sinayskiy + + + TopoLS: Lattice Surgery Compilation via Topological Program Transformations + https://arxiv.org/abs/2601.23109 + arXiv:2601.23109v1 Announce Type: new +Abstract: Fault-tolerant quantum computing with surface codes can be achieved by compiling logical circuits into lattice-surgery instructions. To minimize space-time volume, we present TopoLS, a topological compiler that combines ZX-diagram optimizations with Monte Carlo tree search guided by different operation placements and topology-aware circuit partitioning. Our approach enables scalable exploration of lattice surgery structures and consistently reduces resource overhead. Evaluations of various benchmark algorithms across multiple architectures show that TopoLS achieves an average 33% reduction in space-time volume over prior heuristic-based compilers, while maintaining linear compilation time scaling. Compared to the SAT-solver-based compiler, which provides optimal results only for small circuits before becoming intractable, TopoLS offers an effective and scalable solution for lattice-surgery compilation. + oai:arXiv.org:2601.23109v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Junyu Zhou, Yuhao Liu, Ethan Decker, Justin Kalloor, Mathias Weiden, Kean Chen, Costin Iancu, Gushu Li + + + Free encoding capacity: A universal unit for quantum resources + https://arxiv.org/abs/2601.23116 + arXiv:2601.23116v1 Announce Type: new +Abstract: A perfect d-dimensional quantum channel can convey log d-bits of classical information by encoding messages in d-orthogonal quantum states. Alternatively, for every quantum state at the senders end, there exist d-encoding operations which produce d-orthogonal quantum states. Transmitting which via a d-level perfect quantum channel it is possible to communicate log d-bits of classical information. But what if the set of encoding operations is restricted only within a physically constrained class? Here, we consider such a class of encoding operations to be the set of free operations for any quantum resource theory and show that the constrained capacity - namely, the free encoding capacity (FEC) emerged as a unit of the corresponding quantum resource. Moreover, we show that for the pointed resource theories - a resource theory admitting only a single free state - FEC becomes a faithful resource measure also. We also discuss the implications of FEC in the question of resource-theoretic state transformations and the possibility of extending its faithfulness for general quantum resource theories. + oai:arXiv.org:2601.23116v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Shampa Mondal, Soumajit Das, Preeti Parashar, Tamal Guha + + + Compact U(1) Lattice Gauge Theory in Superconducting Circuits with Infinite-Dimensional Local Hilbert Spaces + https://arxiv.org/abs/2601.23150 + arXiv:2601.23150v1 Announce Type: new +Abstract: We propose a superconducting-circuit architecture that realizes a compact U(1) lattice gauge theory using the intrinsic infinite-dimensional Hilbert space of phase and charge variables. The gauge and matter fields are encoded directly in the degrees of freedom of the rotor variables associated with the circuit nodes, and Gauss's law emerges exactly from the conservation of local charge, without auxiliary stabilizers, penalty terms, or Hilbert-space truncation. A minimal gauge-matter coupling arises microscopically from Josephson nonlinearities, whereas the magnetic plaquette interaction is generated perturbatively via virtual matter excitations. Numerical diagonalization confirms the emergence of compact electrodynamics and coherent vortex excitations, underscoring the need for large local Hilbert spaces in the continuum regime. The required circuit parameters are within the current experimental capabilities. Our results establish superconducting circuits as a scalable, continuous-variable platform for analog quantum simulation of non-perturbative gauge dynamics. + oai:arXiv.org:2601.23150v1 + quant-ph + cond-mat.str-el + hep-lat + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + J. M. Alcaine-Cuervo, S. Pradhan, E. Rico, Z. Shi, C. M. Wilson + + + Complete Hierarchies for the Geometric Measure of Entanglement + https://arxiv.org/abs/2601.23243 + arXiv:2601.23243v1 Announce Type: new +Abstract: In quantum physics, multiparticle systems are described by quantum states acting on tensor products of Hilbert spaces. This product structure leads to the distinction between product states and entangled states; moreover, one can quantify entanglement by considering the distance of a quantum state to the set of product states. The underlying optimization problem occurs frequently in physics and beyond, for instance in the computation of the injective tensor norm in multilinear algebra. Here, we introduce a method to determine the maximal overlap of a pure multiparticle quantum state with product states based on considering several copies of the pure state. This leads to three types of hierarchical approximations to the problem, all of which we prove to converge to the actual value. Besides allowing for the computation of the geometric measure of entanglement, our results can be used to tackle optimizations over stochastic local transformations, to find entanglement witnesses for weakly entangled bipartite states, and to design strong separability tests for mixed multiparticle states. Finally, our approach sheds light on the complexity of separability tests. + oai:arXiv.org:2601.23243v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Lisa T. Weinbrenner, Albert Rico, Kenneth Goodenough, Xiao-Dong Yu, Otfried G\"uhne + + + High-gain effects in broadband continuous-wave parametric down conversion sources and measurements with undetected photons + https://arxiv.org/abs/2601.23263 + arXiv:2601.23263v1 Announce Type: new +Abstract: We study theoretically how high-gain effects affect the measurement outcome of visible signal spectra in undetected photon measurement schemes. We consider two interferometric configurations: firstly, the SU(1,1) interferometer where the idler incurs loss and additional dispersion in between two identical, lossless, squeezers; secondly, the induced coherence interferometer where the idler incurs loss and additional dispersion in between two identical, lossless, squeezers and where the second squeezer is seeded by the idler and a vacuum ancilla mode. Furthermore, we consider a distributed loss configuration where the idler incurs loss as it propagates in the nonlinear medium. Motivated by experimental evidence and due to the fact that broadband sources are ideal for these measurement schemes, we use the dispersive data of a third-order dispersion engineered integrated waveguide parametric down conversion (PDC) source presented in New Journal of Physics 26, 123025 (2024) to model the PDC spectra in the three configurations. For each configuration we consider the case of idler-only (i) absorption, (ii) additional dispersion, and (iii) the combined effects. We obtain results which outline the strength and weaknesses of the different configurations at different operation points. + oai:arXiv.org:2601.23263v1 + quant-ph + physics.optics + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Martin Houde, Franz Roeder, Christine Silberhorn, Benjamin Brecht, Nicol\'as Quesada + + + Understanding multiscale disorder in superconducting nanowire single photon detectors + https://arxiv.org/abs/2601.23277 + arXiv:2601.23277v1 Announce Type: new +Abstract: Superconducting nanowire single-photon detectors are central to applications across quantum information science. Yet, their performance is limited by the effects of disorder and electrodynamic inhomogeneities that are not well understood. By combining DC transport, dark-count measurements, and bias-dependent microwave transmission spectroscopy in the presence of controlled nanoscale disorder introduced through helium-ion irradiation, we distinguish local instability-driven processes from intrinsic superconducting depairing and kinetic inductance nonlinearities. This approach enables systematic tuning of kinetic inductance, depairing currents, microwave dissipation, and mode structure within a single device. Bias- and temperature-dependent resonance shifts quantify disorder-induced modifications of the superconducting density of states through the nonlinear kinetic inductance, while the emergence of multiple resonant modes reveals the formation of electrodynamically distinct superconducting regions. Comparing depairing under current, field, and temperature isolates the dominant microwave loss mechanisms, separating vortex, quasiparticle, and two-level-system contributions, thus providing a robust multifunctional foundation for disorder engineering of superconducting nanowire detectors and resonators. + oai:arXiv.org:2601.23277v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Nirjhar Sarkar, Ronan Gourgues, Yueh-Chun Wu, Chengyun Hua, Katyayani Seal, Andreas Fognini, Steven Randolph, Eugene Dumitrescu, Gabor B. Halasz, Benjamin Lawrie + + + Robust multiparameter estimation using quantum scrambling + https://arxiv.org/abs/2601.23283 + arXiv:2601.23283v1 Announce Type: new +Abstract: We propose and analyze a versatile and efficient multiparameter quantum sensing protocol, which simultaneously estimates many non-commuting and time-dependent signals that are coherently or incoherently coupled to sensing particles. Even in the presence of control imperfections and readout errors, our approach can detect exponentially many parameters in the system size while maintaining the optimal scaling of sensitivity. To accomplish this, scrambling dynamics are leveraged to map distinct signals to unique patterns of bitstring measurements, which distinguishes a large number of signals without significant sensitivity loss. Based on this principle, we develop a computationally efficient protocol utilizing random global Clifford unitaries and evaluate its performance both analytically and numerically. Our protocol naturally extends to scrambling dynamics generated by random local Clifford circuits, local random unitary circuits (RUCs), and ergodic Hamiltonian evolution--commonly realized in near-term quantum hardware--and opens the door to applications ranging from precise noise benchmarking of quantum dynamics to learning time-dependent Hamiltonians. + oai:arXiv.org:2601.23283v1 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Wenjie Gong, Bingtian Ye, Daniel Mark, Soonwon Choi + + + Evolution of Vortex Strings after a Thermal Quench in a Holographic Superfluid + https://arxiv.org/abs/2601.14328 + arXiv:2601.14328v1 Announce Type: cross +Abstract: The formation of topological defects during continuous phase transitions exhibits nonequilibrium universality. While the Kibble-Zurek mechanism (KZM) predicts universal scaling of point-like defect numbers under slow driving, the statistical properties of extended defects remain largely unexplored across both slow and fast protocols. We investigate vortex string formation in a three-dimensional holographic superfluid. For slow quenches, the vortex string number follows KZM scaling, while for rapid quenches, it exhibits complementary universal scaling governed by the final temperature. Beyond the vortex string number, the loop-length distribution reveals a richer structure: individual loops follow the first-return statistics of three-dimensional random walks, $P(\ell) \sim \ell^{-5/2}$. While the total vortex length distribution remains Gaussian, its cumulants obey universal scaling laws with varying power-law exponents, and thus differ markedly from those observed in point-defect systems, indicating distinct statistical features of extended topological defects. + oai:arXiv.org:2601.14328v1 + hep-th + cond-mat.stat-mech + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Chuan-Yin Xia, Andr\'as Grabarits, Hua-Bi Zeng, Adolfo del Campo + + + The Beta-Bound: Drift constraints for Gated Quantum Probabilities + https://arxiv.org/abs/2601.22188 + arXiv:2601.22188v1 Announce Type: cross +Abstract: Quantum mechanics provides extraordinarily accurate probabilistic predictions, yet the framework remains silent on what distinguishes quantum systems from definite measurement outcomes. This paper develops a measurement-theoretic framework for projective gating. The central object is the $\beta$-bound, an inequality that controls how much probability assignments can drift when gating and measurement fail to commute. For a density operator $\rho$, projector $F$, and effect $E$, with gate-passage probability $s = {\rm Tr}(\rho F)$ and commutator norm $\varepsilon = \|[F, E]\|$, the symmetric partial-gating drift satisfies $|\Delta p_F(E)| \leq 2 \sqrt{(1 - s)/s} \cdot \varepsilon$. The constant 2 is sharp. We introduce two diagnostic quantities: the coherence witness $W(\rho, F) = \|F \rho (I - F)\|_1$, measuring cross-boundary coherence, and the record fidelity gap $\Delta_T(\rho_F, R)$, measuring expectation-value change under symmetrisation. Three experimental vignettes demonstrate falsifiability: Hong--Ou--Mandel interferometry, atomic energy-basis dephasing, and decoherence-induced classicality. The framework is operational and interpretation-neutral, compatible with Everettian, Bohmian, QBist, and collapse approaches. It provides quantitative structure that any interpretation must accommodate, along with a template for experimental tests. + oai:arXiv.org:2601.22188v1 + physics.hist-ph + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Jonathon Sendall + + + Andreev spin qubits based on the helical edge states of magnetically doped two-dimensional topological insulators + https://arxiv.org/abs/2601.22226 + arXiv:2601.22226v1 Announce Type: cross +Abstract: We show that Andreev spin qubits can be realized in a Josephson junction based on the helical edge states of a two-dimensional topological insulator (quantum spin Hall system) proximized by superconducting films, in the presence of magnetic doping. We demonstrate that the electrical dipole transitions between the Andreev spin states induced by the magnetic doping can be harnessed to optically manipulate the Andreev spin qubit by microwave radiation pulses. We numerically simulate the realization of NOT and Hadamard quantum logic gates, and discuss implementations in realistic setups. + oai:arXiv.org:2601.22226v1 + cond-mat.mes-hall + cond-mat.supr-con + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Edoardo Latini, Fausto Rossi, Fabrizio Dolcini + + + The metaplectic semigroup and its applications to time-frequency analysis and evolution operators + https://arxiv.org/abs/2601.22252 + arXiv:2601.22252v1 Announce Type: cross +Abstract: We develop a systematic analysis of the metaplectic semigroup $\mathrm{Mp}_+(d,\mathbb{C})$ associated with positive complex symplectic matrices, a notion introduced almost simultaneously and independently by H\"ormander, Brunet, Kramer, and Howe, thereby extending the classical metaplectic theory beyond the unitary setting. + While the existing literature has largely focused on propagators of quadratic evolution equations, for which results are typically obtained via Mehler formulas, our approach is operator-theoretic and symplectic in spirit and adapts techniques from the standard metaplectic group $\mathrm{Mp}(d,\mathbb{R})$ to a substantially broader framework that is not driven by differential problems or particular propagators. + This point of view provides deeper insight into the structure of the metaplectic semigroup, and allows us to investigate its generators, polar decomposition, and intertwining relations with complex conjugation and with the Wigner distribution. We then exploit these structural results to characterize, from a metaplectic perspective, classes of time-frequency representations satisfying prescribed structural properties. Finally, we discuss further implications for parabolic equations with complex quadratic Hamiltonians, we study the boundedness of their propagators on modulation spaces, we obtain estimates in time of their operator norms. Finally, we apply our theory to the study of propagation of Wigner singularities. + oai:arXiv.org:2601.22252v1 + math.AP + math-ph + math.FA + math.MP + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Gianluca Giacchi, Luigi Rodino, Davide Tramontana + + + Photon-graviton polarization entanglement induced by a classical electromagnetic wave + https://arxiv.org/abs/2601.22332 + arXiv:2601.22332v1 Announce Type: cross +Abstract: We study the photon-graviton pair production induced by the propagation of a classical electromagnetic (EM) wave in a Minkowskian spacetime. In our model, the gravitational field is described in terms of the quantized graviton field, whereas the electromagnetic field is split into a classical drive (a linearly or circularly polarized electromagnetic wave) and a quantum fluctuation field. We analyze the time evolution of the quantum state showing that, among other outcomes, the propagation of the EM wave can generate Bell states in the photon-graviton polarization basis. We finally discuss the possibility to observe entangled photons in artificial and natural scenarios. + oai:arXiv.org:2601.22332v1 + gr-qc + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Alessandro Ferreri + + + Quaternionic Perfect Sequences and Hadamard Matrices + https://arxiv.org/abs/2601.22337 + arXiv:2601.22337v1 Announce Type: cross +Abstract: A finite sequence of numbers is perfect if it has zero periodic autocorrelation after a nontrivial cyclic shift. In this work, we study quaternionic perfect sequences having a one-to-one correspondence with the binary sequences arising in Williamson's construction of quaternion-type Hadamard matrices. Using this correspondence, we devise an enumeration algorithm that is significantly faster than previously used algorithms and does not require the sequences to be symmetric. We implement our algorithm and use it to enumerate all circulant and possibly non-symmetric Williamson-type matrices of orders up to 21; previously, the largest order exhaustively enumerated was 13. We prove that when the blocks of a quaternion-type Hadamard matrix are circulant, the blocks are necessarily pairwise amicable. This dramatically improves the filtering power of our algorithm: in order 20, the number of block pairs needing consideration is reduced by a factor of over 25,000. We use our results to construct quaternionic Hadamard matrices of interest in quantum communication and prove they are not equivalent to those constructed by other means. We also study the properties of quaternionic Hadamard matrices analytically, and demonstrate the feasibility of characterizing quaternionic Hadamard matrices with a fixed pattern of entries. These results indicate a richer set of properties and suggest an abundance of quaternionic Hadamard matrices for sufficiently large orders. + oai:arXiv.org:2601.22337v1 + math.CO + cs.DM + cs.IT + math.IT + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Aidan Bennett, Curtis Bright, Paul Colinot, Ashwin Nayak + + + Quantum-Inspired Reinforcement Learning for Secure and Sustainable AIoT-Driven Supply Chain Systems + https://arxiv.org/abs/2601.22339 + arXiv:2601.22339v1 Announce Type: cross +Abstract: Modern supply chains must balance high-speed logistics with environmental impact and security constraints, prompting a surge of interest in AI-enabled Internet of Things (AIoT) solutions for global commerce. However, conventional supply chain optimization models often overlook crucial sustainability goals and cyber vulnerabilities, leaving systems susceptible to both ecological harm and malicious attacks. To tackle these challenges simultaneously, this work integrates a quantum-inspired reinforcement learning framework that unifies carbon footprint reduction, inventory management, and cryptographic-like security measures. We design a quantum-inspired reinforcement learning framework that couples a controllable spin-chain analogy with real-time AIoT signals and optimizes a multi-objective reward unifying fidelity, security, and carbon costs. The approach learns robust policies with stabilized training via value-based and ensemble updates, supported by window-normalized reward components to ensure commensurate scaling. In simulation, the method exhibits smooth convergence, strong late-episode performance, and graceful degradation under representative noise channels, outperforming standard learned and model-based references, highlighting its robust handling of real-time sustainability and risk demands. These findings reinforce the potential for quantum-inspired AIoT frameworks to drive secure, eco-conscious supply chain operations at scale, laying the groundwork for globally connected infrastructures that responsibly meet both consumer and environmental needs. + oai:arXiv.org:2601.22339v1 + cs.LG + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://creativecommons.org/publicdomain/zero/1.0/ + 10.1109/JIOT.2025.3637911 + Muhammad Bilal Akram Dastagir, Omer Tariq, Shahid Mumtaz, Saif Al-Kuwari, Ahmed Farouk + + + Non-Equilibrium Quantum Many-Body Physics with Quantum Circuits + https://arxiv.org/abs/2601.22375 + arXiv:2601.22375v1 Announce Type: cross +Abstract: These are the notes for the 4.5-hour course with the same title that I delivered in August 2025 at the Les Houches summer school ``Exact Solvability and Quantum Information''. In these notes I pedagogically introduce the setting of brickwork quantum circuits and show that it provides a useful framework to study non-equilibrium quantum many-body dynamics in the presence of local interactions. I first show that brickwork quantum circuits evolve quantum correlations in a way that is fundamentally similar to local Hamiltonians, and then present examples of brickwork quantum circuits where, surprisingly, one can compute exactly several relevant dynamical and spectral properties in the presence of non-trivial interactions. + oai:arXiv.org:2601.22375v1 + cond-mat.stat-mech + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Bruno Bertini + + + Quantum $(r,\delta)$-Locally Recoverable BCH and Homothetic-BCH Codes + https://arxiv.org/abs/2601.22567 + arXiv:2601.22567v1 Announce Type: cross +Abstract: Quantum $(r,\delta)$-locally recoverable codes ($(r,\delta)$-LRCs) are the quantum version of classical $(r,\delta)$-LRCs designed to recover multiple failures in large-scale distributed and cloud storage systems. A quantum $(r,\delta)$-LRC, $Q(C)$, can be constructed from an $(r,\delta)$-LRC, $C$, which is Euclidean or Hermitian dual-containing. + This article is devoted to studying how to get quantum $(r,\delta)$-LRCs from BCH and homothetic-BCH codes. As a consequence, we give pure quantum $(r,\delta)$-LRCs which are optimal for the Singleton-like bound. + oai:arXiv.org:2601.22567v1 + cs.IT + math.IT + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Carlos Galindo, Fernando Hernando, Ryutaroh Matsumoto + + + A novel Hamiltonian formulation of $1+1$ dimensional $\phi^4$ theory in Daubechies wavelet basis: momentum space analysis + https://arxiv.org/abs/2601.22953 + arXiv:2601.22953v1 Announce Type: cross +Abstract: We employ the wavelet formalism of quantum field theory to study field theories in the nonperturbative Hamiltonian framework. Specifically, we make use of Daubechies wavelets in momentum space. These basis elements are characterised by a resolution and a translation index that provides for a natural nonperturbative infrared and ultraviolet truncation of the quantum field theory. As an application, we consider the $\phi^4$ theory and demonstrate the emergence of the well-known nonperturbative strong-coupling phase transition in the $m^2>0$ sector. + oai:arXiv.org:2601.22953v1 + hep-th + hep-ex + hep-lat + hep-ph + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://creativecommons.org/publicdomain/zero/1.0/ + Mrinmoy Basak + + + Direct observation of the optical Magnus effect with a trapped ion + https://arxiv.org/abs/2601.22981 + arXiv:2601.22981v1 Announce Type: cross +Abstract: We directly observe and spatially map an optical analog of the Magnus effect, where intrinsic spin-orbit-like coupling of light generates a spin-dependent transverse displacement of the atom-light interaction profile for a $^{40}$Ca$^+$ ion. Probed on a quadrupole transition using a tightly focused beam, we observe displacements of the maximum in the profile of the effective interaction by several 100 nm originating from intrinsic longitudinal electric field components beyond the paraxial approximation. The tight focus of the beam induces additional transverse polarization gradients, which we characterize through a phase-sensitive measurement and spatial maps for different beam configurations. The results establish the physical basis of polarization-gradient interactions relevant to optical tweezer-based quantum control. + oai:arXiv.org:2601.22981v1 + physics.atom-ph + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Philip Leindecker, Louis P. H. Gallagher, Edgar Brucke, Dominique Zehnder, Luka Milanovic, Matteo Marinelli, Rene Gerritsma, Robert J. C. Spreeuw, Jonathan Home, Cornelius Hempel + + + Quasiperiodic Skin Criticality in an Exactly Solvable Non-Hermitian Quasicrystal + https://arxiv.org/abs/2601.23015 + arXiv:2601.23015v1 Announce Type: cross +Abstract: Critical states in quasiperiodic systems defy the conventional dichotomy between extended and localized states. In this work, we demonstrate that non-Hermiticity fundamentally reshapes this paradigm by giving rise to an exactly solvable quasiperiodic critical phase with no energy selectivity. We introduce a non-Hermitian quasiperiodic lattice based on a modulated Hatano-Nelson model and uncover a new universality class of quasiperiodic skin criticality, in which all eigenstates share an identical multifractal spatial structure. Through a nonunitary gauge transformation, the system is mapped onto a disorder-free lattice, enabling exact analytical solutions for the full spectrum and eigenstates. As a consequence, the inverse participation ratio is strictly energy-independent and controlled solely by a global phase. We further show that this criticality persists in multiband lattices, establishing a general and analytically controlled framework for non-Hermitian quasiperiodic critical phenomena. + oai:arXiv.org:2601.23015v1 + cond-mat.mes-hall + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Zhangyuan Chen, Muhammad Idrees, Ying Yang, Xianqi Tong, Xiaosen Yang + + + Spontaneous four-wave mixing in a thin layer with second-order nonlinearity + https://arxiv.org/abs/2601.23137 + arXiv:2601.23137v1 Announce Type: cross +Abstract: Pairs of entangled photons are crucial for photonic quantum technologies. The demand for integrability and multi-functionality suggests 'flat' platforms - ultrathin layers and metasurfaces - as sources of photon pairs. With the success in demonstrating spontaneous parametric down-conversion (SPDC) from such sources, an alternative process to generate photon pairs, spontaneous four-wave mixing (SFWM), also starts to attract interest. In materials with nonzero second-order nonlinear susceptibility $\chi^{(2)}$, SFWM can generate photon pairs both directly, through the third-order nonlinear susceptibility $\chi^{(3)}$, and in a cascaded way, through second harmonic generation (SHG) followed by SPDC. Usually, the cascaded process is more efficient. Here, we show that in a thin layer, direct SFWM dominates, because the wavevector mismatch for SFWM is much smaller than for SHG or SPDC. To demonstrate it, we implement the photon pair generation via SFWM in a second-order nonlinear material - a thin layer of lithium niobate (LN). The existence of both second- and third-order nonlinear processes offers broader opportunities for quantum state engineering. + oai:arXiv.org:2601.23137v1 + physics.optics + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Changjin Son, Maria Chekhova + + + Entanglement Hamiltonians in dissipative free fermions and the time-dependent GGE + https://arxiv.org/abs/2601.23234 + arXiv:2601.23234v1 Announce Type: cross +Abstract: We investigate the dynamics of Entanglement Hamiltonians (EHs) in dissipative free-fermionic systems using a recent operator-based formulation of the quasiparticle picture. Focusing on gain and loss dissipation, we study the post-quench evolution and derive explicit expressions for the EH at the ballistic scale. In the long-time and weak-dissipation regime, the EH is shown to take the form of a time-dependent Generalized Gibbs Ensemble (t-GGE), with a structure that is universal across different initial states of the quench protocol. Within this framework, the emergence of the t-GGE is fully accounted for by the quasiparticle picture, and we argue that this description remains valid whenever the Lindbladian admits an appropriate coarse-grained representation. + oai:arXiv.org:2601.23234v1 + cond-mat.stat-mech + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Riccardo Travaglino, Federico Rottoli, Pasquale Calabrese + + + Weight-four parity checks with silicon spin qubits + https://arxiv.org/abs/2601.23267 + arXiv:2601.23267v1 Announce Type: cross +Abstract: Recent advances in coherent spin shuttling have made sparse semiconductor spin qubit arrays an appealing solid-state platform to realize quantum processors. The dynamic and long-range connectivity enabled by shuttling is also essential for many quantum error-correction (QEC) schemes. Here, we demonstrate a silicon spin-qubit device that comprises a shuttling bus for coherently transporting qubits that can interact at four isolated locations we call bus stops. We dynamically populate the array and tune all single- and two-qubit operations using shuttling and quantum non-demolition (QND) spin measurements, without access to charge sensing in most of the device. We achieve universal control of the effective five-qubit processor and select the connectivity required to form a surface-code stabilizer plaquette that supports X- and Z-type parity checks up to weight-four. We use the parity checks to generate multi-qubit entanglement between all qubit combinations in the array and report the genuine entanglement of a five-qubit Greenberger-Horne-Zeilinger (GHZ) state, constituting the largest such state ever constructed with gate-defined semiconductor spins. This work opens immediate opportunities to pursue QEC experiments with spin qubits, and the protocols developed here lay the groundwork for the modular calibration and operation of sparse spin qubit arrays. + oai:arXiv.org:2601.23267v1 + cond-mat.mes-hall + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Brennan Undseth, Nicola Meggiato, Yi-Hsien Wu, Sam R. Katiraee-Far, Larysa Tryputen, Sander L. de Snoo, Davide Degli Esposti, Giordano Scappucci, Eli\v{s}ka Greplov\'a, Lieven M. K. Vandersypen + + + Analytical topological invariants for 2D non-Hermitian phases using Morse theory + https://arxiv.org/abs/2601.23272 + arXiv:2601.23272v1 Announce Type: cross +Abstract: As energy dissipation and gain are ubiquitous in the real world, such phenomena demand the generalization of Hermitian methods such as the analysis of topological properties for non-Hermitian systems. However, as non-Hermitian systems typically contain more degrees of freedom, this poses a challenge for analytical approaches to understand their topology and invariants. In this work, we analytically calculate the 2D Zak phase for a 2D non-Hermitian SSH-type Hamiltonian that supports a rich structure and edge currents. Closed-form expressions for eigenstates and divisions of the phase diagram are obtained, including for regions in the phase diagram where different types of exceptional points exist. We use Morse theory to determine the topology of exceptional points in momentum space. Although the band structure breaks down at exceptional points, we show that a specific phase-based topological invariant remains well-defined. Furthermore, our work yields an analytic derivation for counting edge states in the Hermitian limit. These results provide new conceptual and analytical tools for the study of complex topological systems. + oai:arXiv.org:2601.23272v1 + cond-mat.mes-hall + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Cameron Gibson, Evelyn Tang + + + Sampling quantum states with inequality constraints + https://arxiv.org/abs/2109.14215 + arXiv:2109.14215v2 Announce Type: replace +Abstract: Random samples of quantum states with specific properties are useful for various applications, such as Monte Carlo integration over the state space. In the high-dimensional situations that one encounters already for a few qubits, the quantum state space has a very complicated boundary, and it is challenging to incorporate the specific properties into the sampling algorithm. In this paper, we present the Sequentially Constrained Monte Carlo (SCMC) algorithm as a powerful and versatile method for sampling quantum states in accordance with any desired properties that can be stated as inequalities. We apply the SCMC algorithm to the generation of samples of bound entangled states; for example, we obtain nearly ten thousand bound entangled two-qutrit states in a few minutes -- a colossal speed-up over independence sampling, which yields less than ten such states per day. In the second application, we draw samples of high-dimensional quantum states from a narrowly peaked target distribution and observe that SCMC sampling remains efficient as the dimension grows. In yet another application, the SCMC algorithm produces uniformly distributed quantum states in regions bounded by values of the problem-specific target distribution; such samples are needed when estimating parameters from the probabilistic data acquired in quantum experiments. + oai:arXiv.org:2109.14215v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Weijun Li, Rui Han, Jiangwei Shang, Hui Khoon Ng, Berthold-Georg Englert + + + On Certified Randomness from Fourier Sampling or Random Circuit Sampling + https://arxiv.org/abs/2111.14846 + arXiv:2111.14846v3 Announce Type: replace +Abstract: Certified randomness has a long history in quantum information, with many potential applications. Recently Aaronson (2018, 2020) proposed a novel public certified randomness protocol based on existing random circuit sampling (RCS) experiments. The security of his protocol, however, relies on non-standard complexity-theoretic conjectures which were not previously studied in the literature. + Inspired by Aaronson's work, we study certified randomness in the quantum random oracle model (QROM). We show that quantum Fourier Sampling can be used to define a publicly verifiable certified randomness protocol with black-box security without any computational assumptions. In addition to giving a certified randomness protocol in the QROM, our work can also be seen as supporting Aaronson's conjectures for RCS-based randomness generation, as our protocol is in some sense the "black-box version" of Aaronson's protocol. In further support of Aaronson's proposal, we prove a Fourier Sampling version of Aaronson's conjecture by extending Raz and Tal's separation of BQP vs PH. + Our work complements the subsequent certified randomness protocol of Yamakawa and Zhandry (2022) in the QROM. Whereas the security of that protocol relied on the Aaronson-Ambainis conjecture, ours does not rely on any computational assumption - at the expense of requiring exponential-time classical verification. Our protocol also has a simple heuristic implementation. + oai:arXiv.org:2111.14846v3 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Roozbeh Bassirian, Adam Bouland, Bill Fefferman, Sam Gunn, Avishay Tal + + + Security framework for quantum key distribution with imperfect sources + https://arxiv.org/abs/2305.05930 + arXiv:2305.05930v5 Announce Type: replace +Abstract: Imperfect bit-and-basis encoders compromise the security of quantum key distribution (QKD) systems via modulation flaws, side channels and inter-pulse correlations, which invalidate standard security proofs. Existing results addressing such imperfections suffer from critical limitations: they either consider only specific flaws, offer an unreasonably poor performance, or require the protocol to be run very slowly. Here, we present a finite-key security proof approach against coherent attacks that incorporates general bit-and-basis encoding imperfections (including modulation flaws, side channels and inter-pulse correlations) while achieving significantly better performances than previous approaches and requiring only partial characterization. + oai:arXiv.org:2305.05930v5 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1364/OPTICAQ.569424 + Optica Quantum 3, 525-534 (2025) + Guillermo Curr\'as-Lorenzo, Margarida Pereira, Go Kato, Marcos Curty, Kiyoshi Tamaki + + + Quantum-enhanced metrology with large Fock states + https://arxiv.org/abs/2306.16919 + arXiv:2306.16919v2 Announce Type: replace +Abstract: Quantum metrology uses non-classical states, such as Fock states with a specific number of photons, to achieve an advantage over classical sensing methods. Typically, quantum metrological performance can be enhanced by increasing the involved excitation numbers, for example, by using large photon-number Fock states. However, manipulating these states and demonstrating a quantum metrological advantage is experimentally challenging. Here we present an efficient method for generating large Fock states approaching 100 photons within a superconducting microwave cavity through the development of a programmable photon number filter. Using these states in displacement and phase measurements, we demonstrate quantum-enhanced metrology approaching the Heisenberg scaling for 40-photon Fock states and achieve a maximum metrological gain of up to 14.8 dB, highlighting the metrological advantages of large Fock states. Our study could be readily extended to mechanical and optical systems, promising potential applications in weak force detection and dark matter searches. + oai:arXiv.org:2306.16919v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1038/s41567-024-02619-5 + Nat. Phys. 20, 1874-1880 (2024) + Xiaowei Deng, Sai Li, Zi-Jie Chen, Zhongchu Ni, Yanyan Cai, Jiasheng Mai, Libo Zhang, Pan Zheng, Haifeng Yu, Chang-Ling Zou, Song Liu, Fei Yan, Yuan Xu, Dapeng Yu + + + Generative quantum machine learning via denoising diffusion probabilistic models + https://arxiv.org/abs/2310.05866 + arXiv:2310.05866v5 Announce Type: replace +Abstract: Deep generative models are key-enabling technology to computer vision, text generation, and large language models. Denoising diffusion probabilistic models (DDPMs) have recently gained much attention due to their ability to generate diverse and high-quality samples in many computer vision tasks, as well as to incorporate flexible model architectures and a relatively simple training scheme. Quantum generative models, empowered by entanglement and superposition, have brought new insight to learning classical and quantum data. Inspired by the classical counterpart, we propose the quantum denoising diffusion probabilistic model (QuDDPM) to enable efficiently trainable generative learning of quantum data. QuDDPM adopts sufficient layers of circuits to guarantee expressivity, while it introduces multiple intermediate training tasks as interpolation between the target distribution and noise to avoid barren plateau and guarantee efficient training. We provide bounds on the learning error and demonstrate QuDDPM's capability in learning correlated quantum noise model, quantum many-body phases, and topological structure of quantum data. The results provide a paradigm for versatile and efficient quantum generative learning. + oai:arXiv.org:2310.05866v5 + quant-ph + cs.AI + cs.LG + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/PhysRevLett.132.100602 + Phys. Rev. Lett. 132, 100602 (2024) + Bingzhi Zhang, Peng Xu, Xiaohui Chen, Quntao Zhuang + + + Quantum speedups for linear programming via interior point methods + https://arxiv.org/abs/2311.03215 + arXiv:2311.03215v3 Announce Type: replace +Abstract: We describe a quantum algorithm based on an interior point method for solving a linear program with $n$ inequality constraints on $d$ variables. The algorithm explicitly returns a feasible solution that is $\varepsilon$-close to optimal, and runs in time $\sqrt{n} \cdot \mathrm{poly}(d,\log(n),\log(1/\varepsilon))$ which is sublinear for tall linear programs (i.e., $n \gg d$). Our algorithm speeds up the Newton step in the state-of-the-art interior point method of Lee and Sidford [FOCS '14]. This requires us to efficiently approximate the Hessian and gradient of the barrier function, and these are our main contributions. + To approximate the Hessian, we describe a quantum algorithm for the \emph{spectral approximation} of $A^T A$ for a tall matrix $A \in \mathbb R^{n \times d}$. The algorithm uses leverage score sampling in combination with Grover search, and returns a $\delta$-approximation by making $O(\sqrt{nd}/\delta)$ row queries to $A$. This generalizes an earlier quantum speedup for graph sparsification by Apers and de Wolf [FOCS '20]. To approximate the gradient, we use a recent quantum algorithm for multivariate mean estimation by Cornelissen, Hamoudi and Jerbi [STOC '22]. While a naive implementation introduces a dependence on the condition number of the Hessian, we avoid this by pre-conditioning our random variable using our quantum algorithm for spectral approximation. + oai:arXiv.org:2311.03215v3 + quant-ph + cs.DS + math.OC + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Simon Apers, Sander Gribling + + + Capacity-Achieving Entanglement Purification Protocol for Pauli Dephasing Channel + https://arxiv.org/abs/2411.14573 + arXiv:2411.14573v2 Announce Type: replace +Abstract: Quantum communication enables secure information transmission and entanglement distribution, but these tasks are fundamentally limited by the capacities of quantum channels. While quantum repeaters can mitigate losses and noise, entanglement swapping via a central node is ineffective against the Pauli dephasing channel due to degradation from Bell-state measurements. This suggests that purifying distributed Bell states before entanglement swapping is necessary. Although one-way hashing codes are known to saturate the dephasing channel capacity, no explicit two-way purification protocol has previously been shown to achieve this bound. In this work, we present a two-way entanglement purification protocol with an explicit, scalable circuit that asymptotically achieves the dephasing channel capacity. With each iteration, the fidelity of Bell states increases. At the final round, the residual dephasing error is suppressed doubly-exponentially, scaling as $\mathcal{O}(p^{2^{n}})$, enabling near-perfect Bell pairs for any fixed number of purification rounds $n$. The explicit circuit we propose is versatile and applicable to any number of Bell pairs, offering a practical solution for mitigating decoherence in quantum networks and distributed. + oai:arXiv.org:2411.14573v2 + quant-ph + math-ph + math.MP + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Ozlem Erkilic, Matthew S. Winnel, Aritra Das, Sebastian Kish, Ping Koy Lam, Jie Zhao, Syed M. Assad + + + Floquet-Thermalization via Instantons near Dynamical Freezing + https://arxiv.org/abs/2412.10498 + arXiv:2412.10498v2 Announce Type: replace +Abstract: Periodically driven Floquet quantum many-body systems have revealed new insights into the rich interplay of thermalization, and growth of entanglement. The phenomenology of dynamical freezing, whereby a translationally invariant many-body system exhibits emergent conservation laws and a slow growth of entanglement entropy at certain fixed ratios of a drive amplitude and frequency, presents a novel paradigm for retaining memory of an initial state upto late times. Previous studies of dynamical freezing have largely been restricted to a high-frequency Floquet-Magnus expansion, and numerical exact diagonalization, which are unable to capture the slow approach to thermalization (or lack thereof) in a systematic fashion. By employing Floquet flow-renormalization, where the time-dependent part of the Hamiltonian is gradually decoupled from the effective Hamiltonian using a sequence of unitary transformations, we unveil the universal approach to dynamical freezing and beyond, at asymptotically late times. We analyze the fixed-point behavior associated with the flow-renormalization at and near freezing using both exact-diagonalization and tensor-network based methods, and contrast the results with conventional prethermal phenomenon. For a generic non-integrable spin Hamiltonian with a periodic cosine wave drive, the flow approaches an unstable fixed point with an approximate emergent symmetry. We observe that at freezing the thermalization timescales are delayed compared to away from freezing, and the flow trajectory undergoes a series of instanton events. Our numerical results are supported by analytical solutions to the flow equations. + oai:arXiv.org:2412.10498v2 + quant-ph + cond-mat.mes-hall + cond-mat.stat-mech + cond-mat.str-el + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Rohit Mukherjee, Haoyu Guo, Debanjan Chowdhury + + + Quantum Circuit Optimization by Graph Coloring + https://arxiv.org/abs/2501.14447 + arXiv:2501.14447v2 Announce Type: replace +Abstract: This work shows that minimizing the depth of a quantum circuit composed of commuting operations reduces to a vertex coloring problem on an appropriately constructed graph, where gates correspond to vertices and edges encode non-parallelizability. The reduction leads to algorithms for circuit optimization by adopting any vertex coloring solver as an optimization backend. The approach is validated by numerical experiments as well as applications to known quantum circuits, including finite field multiplication and QFT-based addition. + oai:arXiv.org:2501.14447v2 + quant-ph + cs.CC + cs.ET + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Hochang Lee, Kyung Chul Jeong, Panjin Kim + + + Efficient Magic State Cultivation on the Surface Code + https://arxiv.org/abs/2502.01743 + arXiv:2502.01743v4 Announce Type: replace +Abstract: Magic state cultivation is a leading approach for generating the resource states required for fault-tolerant quantum computation. Here we present a new cultivation protocol that increases the success probability of magic-state generation in platforms with flexible and non-local connectivity. Our method implements cultivation directly on the surface code, avoiding the detour through alternative, less efficient error-correcting codes used in prior approaches. This both improves the acceptance rate and preserves compatibility with the geometry of the code and the hardware. Numerical simulations show that our protocols improve success probabilities and reduce output error rates compared with protocols tailored to locally connected platforms. Under realistic noise models for cold-atom and trapped-ion systems, we improve the rate of magic state generation by more than a factor of 20. Finally, we study qubit loss and erasure, and show that very low error rates can be achieved with minimal overhead, reaching below $10^{-6}$ infidelity using only nine physical erasure qubits. + oai:arXiv.org:2502.01743v4 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yotam Vaknin, Shoham Jacoby, Arne Grimsmo, Alex Retzker + + + Provable and Verifiable Quantum Advantage in Sample Complexity + https://arxiv.org/abs/2502.08721 + arXiv:2502.08721v3 Announce Type: replace +Abstract: Consider a fixed universe of $N=2^n$ elements and the uniform distribution over elements of some subset of size $K$. Given samples from this distribution, the task of complement sampling is to provide a sample from the complementary subset. We give a simple quantum algorithm that uses only a single quantum sample -- a single copy of the uniform superposition over elements of the subset. When $K=N/2$, we show that the quantum algorithm succeeds with probability $1$, whereas any classical algorithm that succeeds with bounded probability of error requires a number of samples of the order of $N$. This shows that in a sample-to-sample setting, quantum computation can achieve the largest possible separation over classical computation. We show that the same bound can be lifted to prove average-case hardness, paving the way for demonstrations on noisy intermediate-scale quantum (NISQ) computers. It follows that under the assumption of the existence of one-way functions, complement sampling gives provable, verifiable and NISQable quantum advantage in a sample complexity setting. + oai:arXiv.org:2502.08721v3 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/q55v-wm7y + Phys. Rev. Lett. 136, 040601 (2026) + Marcello Benedetti, Harry Buhrman, Jordi Weggemans + + + Digital Quantum Simulation of the Lindblad Master Equation and Its Nonlinear Extensions via Quantum Trajectory Averaging + https://arxiv.org/abs/2504.00121 + arXiv:2504.00121v2 Announce Type: replace +Abstract: Since precisely controlling dissipation in realistic environments is challenging, digital simulation of the Lindblad master equation (LME) is of great significance for understanding nonequilibrium dynamics in open quantum systems. However, achieving long-time simulations for complex systems with multiple dissipation channels remains a major challenge, both theoretically and experimentally. Here, we propose a 1-dilation digital scheme for simulating the LME based on quantum trajectory averaging without postselection. By rigorously matching the stochasticity inherent in quantum trajectories with the probabilistic outcomes of quantum measurements, our method effectively translates the classically established quantum jump algorithm into executable quantum circuits. A key advantage of our method is that it overcomes the exponential suppression of success probability seen in some existing postselection-dependent schemes, especially for long-time evolution or systems with numerous jump operators. Moreover, the scheme can be extended to a 2-dilation framework for the nonlinear LME with postselection, bridging the full LME and non-Hermitian Hamiltonian dynamics. This extended scheme provides a digital approach for exploring the interplay between non-Hermitian Hamiltonians and dissipative terms within a monitored quantum dynamics framework. + oai:arXiv.org:2504.00121v2 + quant-ph + cond-mat.mes-hall + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yu-Guo Liu, Heng Fan, Shu Chen + + + Fault Tolerant Quantum Simulation via Symplectic Transvections + https://arxiv.org/abs/2504.11444 + arXiv:2504.11444v2 Announce Type: replace +Abstract: Conventional approaches to fault-tolerant quantum computing realize logical circuits gate-by-gate, synthesizing each gate independently on one or more code blocks. This incurs excess overhead and doesn't leverage common structures in quantum algorithms. In contrast, we propose a framework that enables the execution of entire logical circuit blocks at once, preserving their global structure. This whole-block approach allows for the direct implementation of logical Trotter circuits - of arbitrary rotation angles - on any stabilizer code, providing a powerful new method for fault tolerant Hamiltonian simulation within a single code block. At the heart of our approach lies a deep structural correspondence between symplectic transvections and Trotter circuits. This connection enables both logical and physical circuits to share the Trotter structure while preserving stabilizer centralization and circuit symmetry even in the presence of non-Clifford rotations. We discuss potential approaches to fault tolerance via biased noise and code concatenation. While we illustrate the key principles using a $[[8,3,3]]$ code, our simulations show that the framework applies to Hamiltonian simulation on even good quantum LDPC codes. These results open the door to new algorithm-tailored, block-level strategies for fault tolerant circuit design, especially in quantum simulation. + oai:arXiv.org:2504.11444v2 + quant-ph + cs.IT + math.IT + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1109/QCE65121.2025.00027 + 2025 IEEE International Conference on Quantum Computing and Engineering (QCE), Albuquerque, NM, USA, 2025, pp. 158-168 + Zhuangzhuang Chen, Jack Owen Weinberg, Narayanan Rengaswamy + + + Quantum Circuits for the Metropolis-Hastings Algorithm + https://arxiv.org/abs/2506.11576 + arXiv:2506.11576v5 Announce Type: replace +Abstract: Szegedy's quantization of a reversible Markov chain provides a quantum walk whose spectral gap is quadratically larger than that of the classical walk. Quantum computers are therefore expected to provide a speedup of Metropolis-Hastings (MH) simulations. Existing generic methods to implement the quantum walk require coherently computing the transition probabilities of the underlying Markov kernel. However, reversible computing methods require a number of qubits that scales with the complexity of the computation. This overhead is undesirable in near-term fault-tolerant quantum computing, where few logical qubits are available. In this work, we present a Szegedy quantum walk construction which follows the classical proposal-acceptance logic, and does not require further reversible computing methods. We also compare this construction with an alternative to Szegedy's approach which also provides a quadratic gap amplification. Since each step of the quantum walks uses a constant number of proposal and acceptance steps, we expect the end-to-end quadratic speedup to hold for MH Markov Chain Monte-Carlo simulations. + oai:arXiv.org:2506.11576v5 + quant-ph + cond-mat.stat-mech + physics.chem-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Baptiste Claudon, Pablo Rodenas-Ruiz, Jean-Philip Piquemal, Pierre Monmarch\'e + + + Cryogenic rf-to-microwave transducer based on a dc-biased electromechanical system + https://arxiv.org/abs/2508.01066 + arXiv:2508.01066v3 Announce Type: replace +Abstract: We report a two-stage, heterodyne rf-to-microwave transducer that combines a tunable electrostatic pre-amplifier with a superconducting electromechanical cavity. A metalized Si$_3$N$_4$ membrane (3 MHz frequency) forms the movable plate of a vacuum-gap capacitor in a microwave LC resonator. A dc bias across the gap converts any small rf signal into a resonant electrostatic force proportional to the bias, providing a voltage-controlled gain that multiplies the cavity's intrinsic electromechanical gain. In a flip-chip device with a 1.5 $\mathrm{\mu}$m gap operated at 10 mK we observe dc-tunable anti-spring shifts, and rf-to-microwave transduction at 49 V bias, achieving a charge sensitivity of 87 $\mathrm{\mu}$e/$\sqrt{\mathrm{Hz}}$ (0.9 nV/$\sqrt{\mathrm{Hz}}$). Extrapolation to sub-micron gaps and state-of-the-art $Q>10^8$ membrane resonators predicts sub-200 fV/$\sqrt{\mathrm{Hz}}$ sensitivity, establishing dc-biased electromechanics as a practical route towards quantum-grade rf electrometers and low-noise modular heterodyne links for superconducting microwave circuits and charge or voltage sensing. + oai:arXiv.org:2508.01066v3 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.5802/crphys.273 + Comptes Rendus. Physique, Volume 27 (2026), pp. 49-63 + Himanshu Patange, Kyrylo Gerashchenko, R\'emi Rousseau, Paul Manset, L\'eo Balembois, Thibault Capelle, Samuel Del\'eglise, Thibaut Jacqmin + + + Conditional squeezing induced by a two-level system: a first-principles approach to QND readout + https://arxiv.org/abs/2508.03506 + arXiv:2508.03506v4 Announce Type: replace +Abstract: We present a systematic Magnus expansion treatment of light-matter interaction beyond the Rotating Wave Approximation. We show that at the second order of Magnus series, the time-evolution operator acquires both energy-shifts and squeezing contributions. In addition to the energy shifts caused by vacuum and photon numbers, the second-order evolution operator contains a term that induces conditional squeezing of the field mode depending on the state of the atom. Such a term suggests a natural mechanism for phase-sensitive, quantum non-demolishing type measurements of squeezed light via homodyne detection. We also show that the second-order Magnus operator in a close SU(1,1) algebra, ensuring the exponentiation of the Magnus series yields a well-defined unitary evolution. By deriving squeezing directly from the Jaynes-Cummings Hamiltonian, our results clarify how energy shifts and $\hat{\sigma}$-dependent squeezing arise from an SU(1,1) structure, with direct implications for phase-sensitive and quantum nondemolition measurements. + oai:arXiv.org:2508.03506v4 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/publicdomain/zero/1.0/ + Phoenix M. M. Paing, Daniel F. V. James + + + State-adaptive quantum error correction and fault-tolerant quantum computing + https://arxiv.org/abs/2508.06011 + arXiv:2508.06011v2 Announce Type: replace +Abstract: We present a theoretical framework for state-adaptive quantum error correction that bridges the gap between quantum computing and error correction paradigms. By incorporating knowledge of quantum states into the error correction process, we establish a new capacity regime governed by quantum mutual information rather than coherent information. This approach reveals a fundamental connection to entanglement-assisted protocols. We demonstrate practical applications in fault-tolerant quantum computation, showing how state-adaptivity enables enhanced error correction without additional measurement overhead. The framework provides insights into quantum channel capacities while offering implementation advantages for current quantum computing platforms. + oai:arXiv.org:2508.06011v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-nc-sa/4.0/ + 10.1103/3z8s-jh28 + Phys. Rev. A 113, 012438 (2026) + D. -S. Wang + + + Carrier-Assisted Entanglement Purification + https://arxiv.org/abs/2509.07514 + arXiv:2509.07514v2 Announce Type: replace +Abstract: Entanglement distillation, a fundamental building block of quantum networks, enables the purification of noisy entangled states shared among distant nodes by local operations and classical communication. Its practical realization presents several technical challenges, including the storage of quantum states in quantum memory and the execution of coherent quantum operations on multiple copies of states within the quantum memory. In this work, we present an entanglement purification protocol via quantum communication, namely a carrier-assisted entanglement purification protocol, which utilizes two elements only: i) quantum memory for a single-copy entangled state shared by parties and ii) single qubits travelling between parties. We show that the protocol, when single-qubit transmission is noiseless, can purify a noisy entangled state shared by parties. When single-qubit transmission is noisy, the purification relies on types of noisy qubit channels; we characterize Pauli channels such that the protocol works for the purification. We address this limitation by using multiple carrier qubits, and show that for any depolarizing channel with channel fidelity greater than 1/2, the protocol's fixed-point fidelity approaches unity as the number of carrier increases. Our results significantly reduce the experimental overhead needed for distilling entanglement, such as quantum memory and coherent operations, making long-distance pure entanglement closer to a practical realization. + oai:arXiv.org:2509.07514v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Jaemin Kim, Karthik Mohan, Sung Won Yun, Joonwoo Bae + + + Addressing requirements for crosstalk-free quantum-gate operation in many-body nanofiber cavity QED systems + https://arxiv.org/abs/2509.08408 + arXiv:2509.08408v2 Announce Type: replace +Abstract: A distributed network architecture in which flying photons connect individual modules containing stationary atomic qubits is a promising approach for scaling up neutral-atom based quantum-computing platforms. We consider an all-fiber based platform consisting of nanofiber cavity QED systems interconnected via conventional optical fibers. Each nanofiber cavity is strongly coupled to multiple atoms through its evanescent field, and atom pairs within one cavity (local) or two distant cavities (remote) are addressed for performing photon-mediated quantum logic gates on them by controlling the effective light-matter coupling via local AC Stark shifts and atom-fiber distance. We numerically evaluate the required parameters for achieving nearly crosstalk-free gate operation using these targeting methods by calculating average gate fidelities, success probabilities, and Pauli error rates for both local and remote controlled-Z gates. For the case of perfect addressing, we also analytically determine the theoretical optimum gate performance as limited by cavity reflectivity, cooperativity, and qubit level-splitting. + oai:arXiv.org:2509.08408v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.1364/JOSAB.578833 + J. Opt. Soc. Am. B 43, 351-365 (2026) + Tim Keller, Seigo Kikura, Rui Asaoka, Yasunari Suzuki, Yuuki Tokunaga, Takao Aoki + + + Quantum Simulation of Fermions in $AdS_2$ Black Hole: Chirality, Entanglement, and Spectral Crossovers + https://arxiv.org/abs/2509.21410 + arXiv:2509.21410v2 Announce Type: replace +Abstract: We consider free Dirac fermions on a discretized $AdS_2$ black hole background, and analyze how curved space redshift, horizons, and the spin connection induced chiral gravitational effect shape spectral, transport, and scrambling phenomena. The system is discretized via staggered fermions followed by the Jordan-Wigner transform to encode the model in qubit degrees of freedom, whose Hamiltonian carries site dependent warp factors and bond chirality terms encoding the redshift and spin connection effects. We calculate the ground state and first excited states energies, their local charge profiles, and their half-chain entanglement entropies, showing how redshift and chirality affect the transition from criticality to a gapped regime. Probing operator growth via out-of-time-order correlators, we find that horizons and the chiral coupling accelerate scrambling, yet remain within a non-chaotic regime. Finally, we map out an integrable to ergodic crossover via level-spacing statistics and Brody fits, and introduce on-site disorder to drive a many body localization transition. + oai:arXiv.org:2509.21410v2 + quant-ph + cond-mat.str-el + gr-qc + hep-lat + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Kazuki Ikeda, Yaron Oz + + + Software-enhanced simultaneous quantum-classical communication protocol with Gaussian post-selection + https://arxiv.org/abs/2510.13138 + arXiv:2510.13138v2 Announce Type: replace +Abstract: Simultaneous quantum-classical communication (SQCC) protocols offer a practical approach to continuous-variable quantum key distribution (CV-QKD) by encoding quantum and classical signals onto the same optical pulse. However, like most QKD protocols, their performance is limited when experimental parameters, such as modulation variance, are optimised based on stationary channel assumptions. In fluctuating environments, such as free-space links, this can result in sub-optimal key rates and reduced transmission distances. In this work, we introduce Gaussian post-selection into the SQCC framework, enabling a software-based optimisation of the modulation variance after channel estimation. This passive approach enhances key rates in both asymptotic and finite-size regimes without requiring hardware modifications and remains effective even when receiver imperfections are taken into account. We demonstrate that our protocol improves the transmission distance and robustness of SQCC relative to the standard fixed-variance SQCC protocol, and approaches the performance of a fully pre-optimised system across both fibre and free-space channels. In particular, we show that the protocol enables full communication windows under ideal weather conditions and maintains higher duty cycles during adverse weather in satellite-to-ground scenarios. These results highlight the practicality of post-selection based SQCC for real-world quantum communication over both terrestrial fibre networks and satellite-based free-space links. + oai:arXiv.org:2510.13138v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Ozlem Erkilic, Biveen Shajilal, Nicholas Zaunders, Timothy C. Ralph + + + Temporal Entanglement Transitions in the Periodically Driven Ising Chain + https://arxiv.org/abs/2510.13970 + arXiv:2510.13970v2 Announce Type: replace +Abstract: Periodically driven quantum systems can host non-equilibrium phenomena without static analogs, including in their entanglement dynamics. Here, we discover $temporal$ $entanglement$ $transitions$ (TET) in a Floquet spin chain, which correspond to a quantum phase transition in the spectrum of the entanglement Hamiltonian and are signaled by dynamical spontaneous symmetry breaking. We identify the symmetry principles underlying these transitions: they appear when the driven Hamiltonian preserves global symmetry (here, $\mathbb{Z}_2$), the initial state respects this symmetry, and the reduced density matrix carries weight in both subsystem-parity sectors, with TET occurring precisely when the sector weights become equal (given the previous two conditions are also satisfied). Intriguingly, we find these transitions across a broad range of driving frequencies (from adiabatic to high-frequency regime) and independently of drive details, where they manifest as periodic, sharp entanglement spectrum reorganizations marked by the Schmidt-gap closure, a vanishing entanglement echo, and symmetry-quantum-number flips, while remaining invisible to conventional local observables. At high frequencies, the entanglement Hamiltonian acquires an intrinsic timescale decoupled from the drive period, rendering the transitions genuine steady-state features. Finite-size scaling reveals universal critical behavior with correlation-length exponent $\nu=1$, matching equilibrium Ising universality despite its emergence from purely dynamical mechanisms decoupled from static criticality. Our work establishes TET as novel features in Floquet quantum matter. + oai:arXiv.org:2510.13970v2 + quant-ph + cond-mat.stat-mech + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Karun Gadge, Abhinav Prem, Rishabh Jha + + + Single-shot antidistinguishability of unitary operations + https://arxiv.org/abs/2510.14609 + arXiv:2510.14609v2 Announce Type: replace +Abstract: The notion of antidistinguishability captures the possibility of ruling out certain alternatives in a quantum experiment without identifying the actual outcome. Although extensively studied for quantum states, the antidistinguishability of quantum channels remains largely unexplored. In this work, we investigate the single-shot antidistinguishability of unitary operations. We analyse two scenarios: antidistinguishability with single-system probes and with entangled probes. For sets of three unitaries, we first prove that all maximally entangled states are equivalent in their performance as probe. In the qubit case, we further establish that maximally entangled probes are always sufficient: if a set of three qubit unitaries is antidistinguishable with either a single-system or non-maximally entangled probe, then it is also antidistinguishable with a maximally entangled one. However, in higher dimension, this equivalence fails. In \textit{dimension 3}, there exists a set of unitaries that are antidistinguishable with non-maximally entangled probe or single-system probe but not with maximally entangled probe. We also establish that union of two antidistinguishable sets of three qubit unitaries also forms a set of antidistinguishable unitaries. Lastly, we provide methods to construct antidistinguishable unitaries from non-antidistinguishable ones. + oai:arXiv.org:2510.14609v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Satyaki Manna, Anandamay Das Bhowmik + + + Scattering theory of frequency-entangled biphoton states facilitated by cavity polaritons + https://arxiv.org/abs/2510.16358 + arXiv:2510.16358v3 Announce Type: replace +Abstract: The use of quantum light to probe exciton properties in semiconductor and molecular nanostructures typically occurs in the low-intensity regime. A substantial enhancement of exciton-photon coupling can be achieved with photonic cavities, where excitons hybridize with cavity modes to form polariton states. To provide a theoretical framework for interpreting emerging experimental efforts in this direction, we develop a scattering theory describing the interaction of frequency-entangled photon pairs with cavity polariton and bipolariton states under various coupling regimes. Employing the Tavis-Cummings model in combination with our scattering approach, we present a quantitative analysis of how the interaction of the entangled photon pair with the polariton/bipolariton modifies its joint spectral amplitude (JSA). Specifically, we examine the effects of the cavity-mode steady-state population, exciton-cavity coupling strength, and different forms of the input photon JSA. Our results show that the entanglement entropy of the scattered photons is highly sensitive to the interplay between the input JSA and the spectral line shapes of the polariton resonances, emphasizing the cavity filtering effects. We suggest that biphoton scattering quantum light spectroscopy best serves as a sensitive probe of polariton and bipolariton states in the photon-vacuum cavity state. Our approach is not only robust to various regimes of cavity-exciton coupling, but also amenable to extensions beyond the Tavis-Cummings model, enabling the representation of a broad class of molecular systems and solid state quantum materials. + oai:arXiv.org:2510.16358v3 + quant-ph + physics.optics + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Andrei Piryatinski, Nishaant Jacobus, Sameer Dambal, Eric R. Bittner, Yu Zhang, Ajay Ram Srimath Kandada + + + Finite-size quantum key distribution rates from R\'enyi entropies using conic optimization + https://arxiv.org/abs/2511.10584 + arXiv:2511.10584v2 Announce Type: replace +Abstract: Finite-size general security proofs for quantum key distribution based on R\'enyi entropies have recently been introduced. These approaches are more flexible and provide tighter bounds on the secret key rate than traditional formulations based on the von Neumann entropy. However, deploying them requires minimizing the conditional R\'enyi entropy, a difficult optimization problem that has hitherto been tackled using ad-hoc techniques based on the Frank-Wolfe algorithm, which are unstable and can only handle particular cases. In this work, we introduce a method based on non-symmetric conic optimization for solving this problem. Our technique is fast, reliable, and completely general. We illustrate its performance on several protocols, whose results represent an improvement over the state of the art. + oai:arXiv.org:2511.10584v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Mariana Navarro, Andr\'es Gonz\'alez Lorente, Pablo V. Parellada, Carlos Pascual-Garc\'ia, Mateus Ara\'ujo + + + Generalized Heralded Generation of Non-Gaussian States Using an Optical Parametric Amplifier + https://arxiv.org/abs/2511.20946 + arXiv:2511.20946v2 Announce Type: replace +Abstract: The heralded optical parametric amplifier (OPA) has emerged as a promising tool for quantum state engineering. However, its potential has been limited to coherent state inputs. Here, we introduce a generalized heralded OPA protocol that unlocks a vastly expanded class of quantum phenomena by accepting arbitrary non-classical inputs. With a squeezed vacuum input, the setup functions as an integrated two-photon subtractor, deterministically generating high-fidelity, larger-amplitude squeezed Schr\"odinger cat states -- an operation previously requiring complex, discrete setups. Furthermore, when fed a small-amplitude SC state, the protocol acts as a non-Gaussianity amplifier, distilling it into high-purity approximations of key quantum resources like specific photon-number superpositions. This work transforms the OPA from a specialized source into a versatile and practical platform for advanced quantum state engineering, enabling the generation of a wide array of non-Gaussian states from a single, integrated setup. + oai:arXiv.org:2511.20946v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/publicdomain/zero/1.0/ + Xiao-Xi Yao, Bo Zhang Yusuf Turek + + + Factorisation conditions and causality for local measurements in QFT + https://arxiv.org/abs/2511.21644 + arXiv:2511.21644v2 Announce Type: replace +Abstract: Quantum operations that are perfectly admissible in non-relativistic quantum theory can enable signalling between spacelike separated regions when naively imported into quantum field theory (QFT). Prominent examples of such "impossible measurements", in the sense of Sorkin, include certain unitary kicks and projective measurements. It is generally accepted that only those quantum operations whose physical implementation arises from a fully relativistically covariant interaction, between the quantum field and a suitable probe, should be regarded as admissible. While this idea has been realised at the level of abstract algebraic QFT, or via particular measurement models, there is still no general set of operational criteria characterising which measurements are physically implementable. In this work we adopt the local S-matrix formalism, and make use of a hierarchy of factorisation conditions that exclude both superluminal signalling and retrocausality, thereby providing such a criterion. Realising the local S-matrices through explicit interactions between smeared field operators and a pointer degree of freedom, we further derive local causality conditions for the induced Kraus operators, which guarantee the absence of signalling in "impossible measurement" scenarios. Finally, we show that the accuracy with which local field observables can be measured is fundamentally limited by the retarded propagator of the field, which also plays an essential role in a factorisation identity we prove for the field Kraus operators. + oai:arXiv.org:2511.21644v2 + quant-ph + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Robin Simmons, Maria Papageorgiou, Marios Christodoulou, \v{C}aslav Brukner + + + Dissipative quantum algorithms for excited-state quantum chemistry + https://arxiv.org/abs/2512.19870 + arXiv:2512.19870v2 Announce Type: replace +Abstract: Electronic excited states are central to a vast array of physical and chemical phenomena, yet accurate and efficient methods for preparing them on quantum devices remain challenging and comparatively underexplored. We introduce a general dissipative algorithm for selectively preparing ab initio electronic excited states. The key idea is to recast excited-state preparation as an effective ground-state problem by suitably modifying the underlying Lindblad dynamics so that the target excited state becomes the unique steady state of a designed quantum channel. We develop three complementary strategies, tailored to different types of prior information about the excited state, such as symmetry and approximate energy. We demonstrate the effectiveness and versatility of these schemes through numerical simulations of atomic and molecular spectra, including valence excitations in prototypical planar conjugated molecules and transition-metal complexes. Taken together, these results provide a new pathway for advancing quantum simulation methods for realistic strongly correlated electronic systems. + oai:arXiv.org:2512.19870v2 + quant-ph + physics.chem-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Hao-En Li, Lin Lin + + + Quantum Universality in Composite Systems: A Trichotomy of Clifford Resources + https://arxiv.org/abs/2512.20787 + arXiv:2512.20787v2 Announce Type: replace +Abstract: The Clifford group is efficiently classically simulable, and universality is obtained by supplementing it with non-Clifford resources. We determine which single-qudit gates suffice to achieve universality. We show that the structure of such resources is governed by the prime factorization of the qudit dimension $d$. Using the adjoint action on the space of complex trace-zero matrices, we relate density to irreducibility together with an infiniteness criterion, yielding a trichotomy based on the factorization of $d$. When $d$ is prime, any non-Clifford gate generates a dense subgroup of the determinant-one unitaries. If $d$ is a prime power, the adjoint action is reducible, and universality requires gates that couple the resulting invariant subspaces. For composite $d$ with pairwise coprime factors, generalized intra-qudit controlled-NOT gates connecting the factors already suffice. These findings suggest that ``composite architectures'' -- hybrid registers combining incommensurate dimensions -- offer a route to bypass the standard overhead associated with magic-state injection. + oai:arXiv.org:2512.20787v2 + quant-ph + math-ph + math.MP + math.RT + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Alejandro Borda, Julian Rincon, C\'esar Galindo + + + A game-theoretic probability approach to loopholes in CHSH experiments + https://arxiv.org/abs/2601.09339 + arXiv:2601.09339v2 Announce Type: replace +Abstract: We study the CHSH inequality from an informational, timing-sensitive viewpoint using game-theoretic probability, which avoids assuming an underlying probability space. The locality loophole and the measurement-dependence (``freedom-of-choice'') loophole are reformulated as structural constraints in a sequential hidden-variable game between Scientists and Nature. We construct a loopholes-closed game with capital processes that test (i) convergence of empirical conditional frequencies to the CHSH correlations and (ii) the absence of systematic correlations between measurement settings and Nature's hidden-variable assignments, and prove that Nature cannot satisfy both simultaneously: at least one capital process must diverge. This yields an operational winning strategy for Scientists and a game-theoretic probabilistic interpretation of experimentally observed CHSH violations. + oai:arXiv.org:2601.09339v2 + quant-ph + cs.GT + math.PR + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Takara Nomura, Koichi Yamagata, Akio Fujiwara + + + Complex scalar relativistic field as a probability amplitude + https://arxiv.org/abs/2601.10302 + arXiv:2601.10302v2 Announce Type: replace +Abstract: A relativistic equation for a neutral complex field as a probability amplitude is proposed. The continuity equation for the probability density is obtained. It is shown that there are two types of excitations of this field, which describe particles with positive energy and different dispersion laws. Based on the Lagrangian formalism, conservation laws are obtained. The transition to secondary quantization is considered. + oai:arXiv.org:2601.10302v2 + quant-ph + hep-th + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Yu. M. Poluektov + + + Pauli Propagation for Imaginary-Time Evolution + https://arxiv.org/abs/2601.14400 + arXiv:2601.14400v2 Announce Type: replace +Abstract: We extend the Pauli Propagation framework to simulate imaginary-time evolution. By deriving explicit update rules for the propagation of Pauli operators under imaginary-time evolution generated by Pauli strings, we introduce an imaginary-time Pauli Propagation (ITPP) algorithm for approximating imaginary-time dynamics directly in the Pauli basis. This approach enables the computation of thermal and ground-state properties while retaining the key computational advantages of Pauli Propagation. Benchmarking ITPP on the one-dimensional transverse-field Ising model demonstrates that truncation provides a controlled trade-off between accuracy and computational cost, while also revealing challenges associated with operator growth under imaginary-time evolution. Finally, combining imaginary-time and real-time Pauli Propagation naturally suggests a pathway toward simulating open quantum system dynamics within a unified framework. + oai:arXiv.org:2601.14400v2 + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Rafael G\'omez-Lurbe, Armando P\'erez + + + Quantum Super-resolution by Adaptive Non-local Observables + https://arxiv.org/abs/2601.14433 + arXiv:2601.14433v2 Announce Type: replace +Abstract: Super-resolution (SR) seeks to reconstruct high-resolution (HR) data from low-resolution (LR) observations. Classical deep learning methods have advanced SR substantially, but require increasingly deeper networks, large datasets, and heavy computation to capture fine-grained correlations. In this work, we present the \emph{first study} to investigate quantum circuits for SR. We propose a framework based on Variational Quantum Circuits (VQCs) with \emph{Adaptive Non-Local Observable} (ANO) measurements. Unlike conventional VQCs with fixed Pauli readouts, ANO introduces trainable multi-qubit Hermitian observables, allowing the measurement process to adapt during training. This design leverages the high-dimensional Hilbert space of quantum systems and the representational structure provided by entanglement and superposition. Experiments demonstrate that ANO-VQCs achieve up to five-fold higher resolution with a relatively small model size, suggesting a promising new direction at the intersection of quantum machine learning and super-resolution. + oai:arXiv.org:2601.14433v2 + quant-ph + cs.AI + cs.LG + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Hsin-Yi Lin, Huan-Hsin Tseng, Samuel Yen-Chi Chen, Shinjae Yoo + + + Quantum Fisher information analysis for absorption measurements with undetected photons + https://arxiv.org/abs/2601.16941 + arXiv:2601.16941v2 Announce Type: replace +Abstract: We theoretically compare the quantum Fisher information (QFI) for three configurations of absorption spectroscopy with undetected idler photons: an SU(1,1) interferometer with inter-source idler loss, an induced-coherence (IC) setup in which the idler partially seeds a second squeezer together with a vacuum ancilla, and a distributed-loss (DL) scheme with in-medium attenuation. We calculate the QFI as a function of parametric gain for both full and signal-only detection access. For losses below 99% and low to moderate gain, the SU(1,1) configuration provides the largest QFI. At high gain and intermediate loss, the IC scheme performs best, while under extreme attenuation (transmission $<$ 1%) the DL model becomes optimal. These results delineate the measurement regimes in which each architecture is optimal in terms of information theory. + oai:arXiv.org:2601.16941v2 + quant-ph + physics.optics + Mon, 02 Feb 2026 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Martin Houde, Franz Roeder, Christine Silberhorn, Benjamin Brecht, Nicol\'as Quesada + + + Symmetry-Enforced Quadratic Degradability Beyond Low Dimensions + https://arxiv.org/abs/2401.16312 + arXiv:2401.16312v5 Announce Type: replace-cross +Abstract: Approximate degradability provides a powerful framework for bounding the quantum and private capacities of noisy quantum channels in regimes where exact degradability fails. While generic low-noise channels exhibit a non-degradability parameter that decays as a fractional power of the noise strength, certain symmetric channels are known to display an enhanced quadratic suppression. In this work, we investigate the structural origin of this phenomenon through a family of high-dimensional, rotationally symmetric noise models constructed from angular momentum operators. We first establish that the pure noise component of these channels is maximally distinguishable from the identity channel in diamond norm, revealing a geometric orthogonality between signal and noise. Building on this structure, we construct an explicit symmetric degrading map and prove that the approximate degradability parameter scales quadratically with the noise parameter for all system dimensions. To clarify the mechanism behind this behavior, we identify algebraic conditions on the noise operators that guarantee the cancellation of leading-order non-degradability terms. These conditions apply not only to the rotationally symmetric model studied here, but also to a distinct family of high-dimensional depolarizing channels based on discrete unitary operator bases. Numerical evaluations of capacity lower bounds further illustrate the practical impact of the quadratic suppression. Together, these results demonstrate that enhanced approximate degradability arises from symmetry-induced orthogonality and invariance properties, rather than from low-dimensional or model-specific effects. + oai:arXiv.org:2401.16312v5 + cs.IT + math.IT + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yun-Feng Lo, Yen-Chi Lee, Min-Hsiu Hsieh + + + Entanglement dynamics from universal low-lying modes + https://arxiv.org/abs/2407.16763 + arXiv:2407.16763v3 Announce Type: replace-cross +Abstract: Information-theoretic quantities such as Renyi entropies show a remarkable universality in their late-time behaviour across a variety of chaotic many-body systems. Understanding how such common features emerge from very different microscopic dynamics remains an important challenge. In this work, we address this question in a class of Brownian models with random time-dependent Hamiltonians and a variety of different microscopic couplings. In any such model, the Lorentzian time-evolution of the $n$-th Renyi entropy can be mapped to evolution by a Euclidean Hamiltonian on 2$n$ copies of the system. We provide evidence that in systems with no symmetries, the low-energy excitations of the Euclidean Hamiltonian are universally given by a gapped quasiparticle-like band. The eigenstates in this band are plane waves of locally dressed domain walls between ferromagnetic ground states associated with two permutations in the symmetric group $S_n$. These excitations give rise to the membrane picture of entanglement growth, with the membrane tension determined by their dispersion relation. We establish this structure in a variety of cases using analytical perturbative methods and numerical variational techniques, and extract the associated dispersion relations and membrane tensions for the second and third Renyi entropies. For the third Renyi entropy, we argue that phase transitions in the membrane tension as a function of velocity are needed to ensure that physical constraints on the membrane tension are satisfied. Overall, this structure provides an understanding of entanglement dynamics in terms of a universal set of gapped low-lying modes, which may also apply to systems with time-independent Hamiltonians. + oai:arXiv.org:2407.16763v3 + cond-mat.stat-mech + cond-mat.str-el + hep-th + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/prp6-y5hl + Phys. Rev. B 113, 014308 (2026) + Shreya Vardhan, Sanjay Moudgalya + + + Measurement-Induced Crossover of Quantum Jump Statistics in Postselection-Free Many-Body Dynamics + https://arxiv.org/abs/2503.02418 + arXiv:2503.02418v2 Announce Type: replace-cross +Abstract: We reveal a nontrivial crossover of subsystem fluctuations of quantum jumps in continuously monitored many-body systems, which have a trivial maximally mixed state as a steady-state density matrix. While the fluctuations exhibit the standard volume law $\propto L$ following Poissonian statistics for sufficiently weak measurement strength, anomalous yet universal scaling law $\propto L^\alpha \:(\alpha\sim 2.7$ up to $L=20)$ indicating super-Poissonian statistics appears for strong measurement strength. This drastically affects the precision of estimating the rate of quantum jumps: for strong (weak) measurement, the estimation uncertainty is enhanced (suppressed) as the system size increases. We demonstrate that the anomalous scaling of the subsystem fluctuation originates from an integrated many-body autocorrelation function and that the transient dynamics contributes to the scaling law rather than the Liouvillian gap. The measurement-induced crossover is accessed only from the postselection-free information obtained from the time and the position of quantum jumps and can be tested in ultracold atom experiments. + oai:arXiv.org:2503.02418v2 + cond-mat.stat-mech + cond-mat.quant-gas + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Kazuki Yamamoto, Ryusuke Hamazaki + + + Quantum latent distributions in deep generative models + https://arxiv.org/abs/2508.19857 + arXiv:2508.19857v2 Announce Type: replace-cross +Abstract: Many successful families of generative models leverage a low-dimensional latent distribution that is mapped to a data distribution. Though simple latent distributions are often used, the choice of distribution has a strong impact on model performance. Recent experiments have suggested that the probability distributions produced by quantum processors, which are typically highly correlated and classically intractable, can lead to improved performance on some datasets. However, when and why latent distributions produced by quantum processors can improve performance, and whether these improvements are connected to quantum properties of these distributions, are open questions that we investigate in this work. We show in theory that, under certain conditions, these "quantum latent distributions" enable generative models to produce data distributions that classical latent distributions cannot efficiently produce. We provide intuition as to the underlying mechanisms that could explain a performance advantage on real datasets. Based on this, we perform extensive benchmarking on a synthetic quantum dataset and the QM9 molecular dataset, using both simulated and real photonic quantum processors. We find that the statistics arising from quantum interference lead to improved generative performance compared to classical baselines, suggesting that quantum processors can play a role in expanding the capabilities of deep generative models. + oai:arXiv.org:2508.19857v2 + cs.LG + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Omar Bacarreza, Thorin Farnsworth, Alexander Makarovskiy, Hugo Wallner, Tessa Hicks, Santiago Sempere-Llagostera, John Price, Robert J. A. Francis-Jones, William R. Clements + + + Spin-orbit coupled spin-boson model : A variational analysis + https://arxiv.org/abs/2510.26468 + arXiv:2510.26468v2 Announce Type: replace-cross +Abstract: The spin-boson (SB) model is a standard prototype for quantum dissipation, which we generalize in this work, to explore the dissipative effects on a one-dimensional spin-orbit (SO) coupled particle in the presence of a sub-ohmic bath. We analyze this model by extending the well-known variational polaron approach, revealing a localization transition accompanied by an intriguing change in the spectrum, for which the doubly degenerate minima evolves to a single minimum at zero momentum as the system-bath coupling increases. For translational invariant system with conserved momentum, a continuous magnetization transition occurs, whereas the ground state changes discontinuously. We further investigate the transition of the ground state in the presence of harmonic confinement, which effectively models a quantum dot-like nanostructure under the influence of the environment. In both the scenarios, the entanglement entropy of the spin-sector can serve as a marker for these transitions. Interestingly, for the trapped system, a cat-like superposition state corresponds to maximum entanglement entropy below the transition, highlighting the relevance of the present model for studying the effect of decoherence on intra-particle entanglement in the context of quantum information processing. + oai:arXiv.org:2510.26468v2 + cond-mat.stat-mech + cond-mat.quant-gas + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + 10.1103/p785-pgkr + Physical Review B 113, 024438 (2026) + Sudip Sinha, Subhasis Sinha, Sushanta Dattagupta + + + Searching for axion dark matter with magnetic resonance force microscopy + https://arxiv.org/abs/2512.12120 + arXiv:2512.12120v2 Announce Type: replace-cross +Abstract: We propose a magnetic resonance force microscopy (MRFM) search for axion dark matter around 1 GHz. The experiment leverages the axion's derivative coupling to electrons, which induces an effective A.C. magnetic field on a sample of electron spins polarized by a D.C. magnetic field and a micromagnet. A second pump field at a nearby frequency enhances the signal, with the detuning matched to the resonant frequency of a magnet-loaded mechanical oscillator. The resulting spin-dependent force is detected with hih sensitivity via optical interferometry. Accounting for the relevant noise sources, we show that current technology can be used to put constraints competitive with those from laboratory experiments with just a minute of integration time. Furthermore, varying the pump field frequency and D.C. magnetic field allows one to scan the axion mass. Finally, we explore this setup's capability to put constraints on other dark matter - Standard Model couplings. + oai:arXiv.org:2512.12120v2 + hep-ph + astro-ph.IM + quant-ph + Mon, 02 Feb 2026 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Elham Kashi, Muhammad Hani Zaheer, Ryan Petery, Swati Singh +