Showing 1–50 of 233 results for author: Zhang, T

Hundred-hertz quantum circuit iteration rate in a reusable neutral-atom array

Authors: Liang Chen, Wen-Yi Zhu, Dong-Qi Ma, Tian-Yang Zhang, Zi-Jie Chen, Yi-Chen Zhang, Hong-Jie Fan, Guang-Jie Chen, Qing-Xuan Jie, Wei-Zhou Cai, Tian-Cai Zhang, Luyan Sun, Yan-Lei Zhang, Xi-Feng Ren, Guang-Can Guo, Zhu-Bo Wang, Ya-Dong Hu, Gang Li, Chang-Ling Zou

Abstract: Neutral-atom quantum processors have rapidly advanced in scale and coherence, yet their practical performance remains constrained by limited quantum circuit iteration rates (qCIRs) and information throughput. Here we experimentally demonstrate a high-throughput neutral-atom system based on non-destructive readout and atom reuse. By integrating a chip-based photonic interface with a 10-qubit array,… ▽ More Neutral-atom quantum processors have rapidly advanced in scale and coherence, yet their practical performance remains constrained by limited quantum circuit iteration rates (qCIRs) and information throughput. Here we experimentally demonstrate a high-throughput neutral-atom system based on non-destructive readout and atom reuse. By integrating a chip-based photonic interface with a 10-qubit array, we implement non-destructive readout with a retention probability of 99.7%, and further achieve a raw qCIR of 101Hz and a post-selected qCIR of 74.8Hz. More importantly, we verify a general throughput optimization methodology and obtain a normalized Fisher information rate of 57.7Hz, improving the achievable throughput by more than one order of magnitude compared with conventional methods. Our results establish a practical route toward high-throughput neutral-atom quantum processors. △ Less

Submitted 17 August, 2026; originally announced August 2026.

A scalable chip-integrated single-photon source array based on 50 individually addressable neutral atoms

Authors: Ya-Dong Hu, Tian-Yang Zhang, Dong-Qi Ma, Yi-Chen Zhang, Liang Chen, Wen-Yi Zhu, Hong-Jie Fan, Yan-Lei Zhang, Zhu-Bo Wang, Gang Li, Xi-Feng Ren, Guang-Can Guo, Chang-Ling Zou

Abstract: Scalable arrays of identical single-photon sources are a central resource for photonic quantum information processing, quantum networks and quantum metrology. Neutral atoms provide intrinsically identical emitters that can be assembled and rearranged in optical tweezers, but a many-channel fiber interface to individually trapped atoms has remained a major technical challenge. Here we demonstrate a… ▽ More Scalable arrays of identical single-photon sources are a central resource for photonic quantum information processing, quantum networks and quantum metrology. Neutral atoms provide intrinsically identical emitters that can be assembled and rearranged in optical tweezers, but a many-channel fiber interface to individually trapped atoms has remained a major technical challenge. Here we demonstrate a chip-interfaced single-photon source array based on 50 individually addressable $^{87}\mathrm{Rb}$ atoms. A glass waveguide fan-out converts the \SI{5}{\micro m} pitch of the optical-tweezer array to the \SI{127}{\micro m} pitch of a commercial fiber array, mapping each atom to its own waveguide, fiber and single-photon detector. We resolve all 50 channels with an average nearest-neighbor cross-talk of $0.4\%$ and a uniform insertion loss of \SI{2.9}{dB}, and verify single-photon emission with $g^{(2)}(0)=0.29$, presently limited by detector dark counts and residual cooling-light scattering. Combining per-channel atom discrimination, rearrangement and reservoir replenishment, we prepare source subarrays of up to 24 atoms with a $93\%$ fill fraction. For small target numbers, atom loss is repaired from the reservoir at the detection-limited rate of \SI{118}{Hz}. We further fabricate a 784-channel waveguide chip, showing that the photonic interface can be extended well beyond the present number. This architecture establishes a fiber-native neutral-atom platform for larger arrays of identical single-photon sources. △ Less

Submitted 16 August, 2026; originally announced August 2026.

Scalar Finite-Proper-Time Field Theory as Spectral Operator Calculus

Authors: Mustafa Bakr, Tongyu Zhang

Abstract: We formulate a finite-proper-time construction for Euclidean scalar $λφ^4$ theory in which a retained endpoint $s_0$ is assigned to complete internal histories rather than independently to individual Schwinger segments. The theory is defined through paired open and closed spectral functions and their Fréchet/Duhamel hierarchy. Functional differentiation inserts operators along an existing proper-t… ▽ More We formulate a finite-proper-time construction for Euclidean scalar $λφ^4$ theory in which a retained endpoint $s_0$ is assigned to complete internal histories rather than independently to individual Schwinger segments. The theory is defined through paired open and closed spectral functions and their Fréchet/Duhamel hierarchy. Functional differentiation inserts operators along an existing proper-time history and partitions its total length, while interaction vertices sew separately complete histories. We introduce a corresponding complete-history diagrammatic calculus and derive the resulting one- and two-loop structures. We distinguish the retained endpoint from an auxiliary regulator or renormalisation-group scale and test whether its effects survive ordinary parameter matching and admissible field redefinitions. For the one-loop four-point function, fixing the renormalised mass, field normalisation, and quartic coupling leaves a finite momentum-dependent remainder. We establish a perturbative non-redundancy description of the retained endpoint against finite renormalisable-parameter redefinitions and local $S$-matrix-preserving field redefinitions at this order. The low-energy theory can be represented as an effective field theory, but its higher-derivative coefficients are not independent. This provides a concrete distinction between a retained finite proper-time scale and an arbitrary cutoff prescription. △ Less

Submitted 12 August, 2026; originally announced August 2026.

Quantum correlations of tripartite mixed states in the black hole quantum atmosphere

Authors: Anqi Zhang, Yanze Zheng, Xiaofen Huang, Tinggui Zhang

Abstract: We investigate quantum state texture, genuine multipartite entanglement, and tripartite nonlocality of a tripartite mixed state in the black hole quantum atmosphere. By introducing the Hartle-Hawking local temperature into the Bogoliubov coefficients, we characterize the influence of the local Hawking effect on both physically accessible and inaccessible reduced states. We find that the extrema of… ▽ More We investigate quantum state texture, genuine multipartite entanglement, and tripartite nonlocality of a tripartite mixed state in the black hole quantum atmosphere. By introducing the Hartle-Hawking local temperature into the Bogoliubov coefficients, we characterize the influence of the local Hawking effect on both physically accessible and inaccessible reduced states. We find that the extrema of these three quantities all lie in the same near horizon region and shift outward with increasing local Hawking temperature, coinciding with the peak region of the local Hawking temperature and indicating that different aspects of tripartite quantum information are most sensitive to the local Hawking effect in the same atmospheric region. In contrast to genuine multipartite entanglement, tripartite nonlocality is more fragile and is suppressed under stronger local Hawking effects. These results provide a unified characterization of density matrix restructuring, entanglement redistribution, and nonlocality in tripartite mixed states affected by the black hole quantum atmosphere. △ Less

Submitted 15 July, 2026; originally announced July 2026.

Low-latency FPGA-based electronic control system for fast preparation of defect-free atom arrays

Authors: Ya-Dong Hu, Dong-Qi Ma, Tian-Yang Zhang, Liang Chen, Yi-Chen Zhang, Xiao-Kang Zhong, Wen-Yi Zhu, Hong-Jie Fan, Qing-Xuan Jie, Yan-Lei Zhang, Gang Li, Xi-Feng Ren, Xu-Liang Zhang, Guang-Can Guo, Zhu-Bo Wang, Chang-Ling Zou

Abstract: The scalability of neutral atom quantum computing demands integrated electronic control systems with low latency, modular architecture, and real-time feedback capability. Here, we present an FPGA-based electronic control system that eliminates the PC from the feedback loop, integrating photon counting, real-time decision-making, and waveform generation within a unified PXIe architecture. The syste… ▽ More The scalability of neutral atom quantum computing demands integrated electronic control systems with low latency, modular architecture, and real-time feedback capability. Here, we present an FPGA-based electronic control system that eliminates the PC from the feedback loop, integrating photon counting, real-time decision-making, and waveform generation within a unified PXIe architecture. The system achieves a total feedback latency of $282\,\mathrm{μs}$ and is validated in practical experiments by assembling defect-free atom arrays from 24 stochastically loaded optical tweezers. A single-round rearrangement achieves a filling fraction of $\sim96\%$, while feedback-controlled iterative rearrangement over five rounds boosts the success probability for generating a 10-atom defect-free array from $65.7\%$ to $95.4\%$. This system establishes the electronic infrastructure necessary for mid-circuit measurement and real-time quantum error correction on neutral-atom platforms. △ Less

Submitted 9 July, 2026; originally announced July 2026.

Comments: 8 pages, 5 figures

Quantum Communication Lower Bounds for Search Problems via Matrix Discrepancy

Authors: Minbo Gao, Chenghua Liu, Guangxu Yang, Tianyi Zhang

Abstract: We study one-way quantum communication lower bounds for search problems. Unlike decision problems, search problems can have many valid outputs, which pose a fundamental barrier to standard quantum lower-bound techniques. We overcome this by developing a novel method based on matrix discrepancy, which allows us to bound the output measurements of a quantum protocol jointly. As applications of our… ▽ More We study one-way quantum communication lower bounds for search problems. Unlike decision problems, search problems can have many valid outputs, which pose a fundamental barrier to standard quantum lower-bound techniques. We overcome this by developing a novel method based on matrix discrepancy, which allows us to bound the output measurements of a quantum protocol jointly. As applications of our method, we establish the first tight quantum lower bounds for two fundamental search problems in some natural parameter regimes: collision finding and triangle finding. For collision finding, we prove a tight $Ω(N^{1/4})$ one-way quantum communication lower bound. Previously, the best-known quantum communication lower bound for collision finding was $Ω(N^{1/12})$ due to Göös and Jain (RANDOM 2022), and no stronger bound was known even under the one-way restriction. For triangle finding in graph streams, we prove a one-pass quantum streaming space lower bound of $Ω\left(\sqrt{Δ_V}\right)$ for graphs with $m$ edges, $Θ(m)$ triangles, and constant $Δ_E$, where $Δ_V$ and $Δ_E$ denote the maximum number of triangles sharing a common vertex and edge, respectively, under the condition that $1\le Δ_V\le m^{2/3}$. This constitutes the first nontrivial quantum space lower bound in this regime, matching the classical upper bound of Jayaram and Kallaugher (RANDOM 2021) up to logarithmic factors. Notably, our method also recovers the classical lower bound of Kallaugher and Price (SODA 2017) through an entirely different argument, avoiding their Boolean-Hidden-Matching reduction that breaks down for quantum protocols. △ Less

Submitted 9 July, 2026; originally announced July 2026.

Comments: 26 pages, 1 figure

Quantum percolation based dynamic propagation connectivity for critical-area identification in transport networks

Authors: Junxiang Xu, Chence Niu, Vinayak Dixit, Divya Jayakumar Nair, Tingting Zhang

Abstract: Transport networks often lose functionality through gradual degradation in link operating conditions before topological disconnection occurs. Link-centred and binary percolation measures identify important facilities or connectivity failures, but they provide limited information on which spatial areas cause the largest loss of network-wide propagation capability. This paper develops a Dynamic Prop… ▽ More Transport networks often lose functionality through gradual degradation in link operating conditions before topological disconnection occurs. Link-centred and binary percolation measures identify important facilities or connectivity failures, but they provide limited information on which spatial areas cause the largest loss of network-wide propagation capability. This paper develops a Dynamic Propagation Connectivity (DPC) metric based on quantum percolation for critical-area identification in transport networks. Time-varying link travel times are converted into continuous propagation strengths, which define a Hermitian propagation operator at each observation time. Candidate regions are then evaluated by a regional degradation experiment that measures the resulting loss of DPC. The method is applied to a benchmark Sioux Falls network and six Florida road networks during the post-Hurricane Irma disruption and recovery period, using 1,281 five-minute observation times. The benchmark confirms that the regional DPC score identifies a predefined structurally critical corridor. In the Florida networks, the identified critical areas differ from regions selected by link count, local degradation, edge betweenness, algebraic connectivity, and classical percolation. In Networks 1 to 4, DPC and classical percolation rankings have negative Spearman correlations, showing that continuous propagation degradation and binary fragmentation reveal different vulnerability patterns. Robustness tests under alternative travel time scaling, degradation strength, and grid size show stable results, with mean rank agreement between 0.84 and 0.96. The findings extend transport resilience analysis based on percolation from binary connectivity loss to continuous propagation degradation and provide a spatial diagnostic tool for regional monitoring, emergency planning, and recovery prioritisation. △ Less

Submitted 29 June, 2026; originally announced June 2026.

Gaussian quantum steering of coupled three-mode squeezed vacuum in an expanding universe

Authors: Guang-Wei Mi, Xiaofen Huang, Tinggui Zhang

Abstract: The coupled three-mode squeezed vacuum is a representative multimode squeezed Gaussian state featuring unique steerability. This work investigates Gaussian quantum steering distributions of the coupled three-mode squeezed vacuum under an expanding universe. Due to causal separation between the interior and exterior spacetime regions, quantum information behind the event horizon is inaccessible to… ▽ More The coupled three-mode squeezed vacuum is a representative multimode squeezed Gaussian state featuring unique steerability. This work investigates Gaussian quantum steering distributions of the coupled three-mode squeezed vacuum under an expanding universe. Due to causal separation between the interior and exterior spacetime regions, quantum information behind the event horizon is inaccessible to Alice, Bob and Charlie. We separately analyze steering behaviors for physically accessible and inaccessible modes. Our analysis shows that greater total mean photon number and momentum, combined with reduced expansion volume and expansion rate, enhance quantum steering strength. Notably, Gaussian quantum steering for physically inaccessible modes undergoes the "sudden death" phenomenon when a critical threshold parameter $φ$ is exceeded. These results deliver novel insights into quantum correlations in curved spacetime. △ Less

Submitted 27 June, 2026; originally announced June 2026.

Comments: 11 pages, 8 figures

Experiment-compatible measurement--feedback quantum state preparation with reinforcement learning

Authors: Xiaotian Nie, Tao Zhang, Linghui Chen

Abstract: Ground-state preparation is a critical task in quantum simulation and quantum computing, as it enables the study of correlated phases and the generation of entangled resource states. While measurement--feedback control has emerged as a promising route to state preparation, existing schemes either rely on handcrafted, task-specific policies or are designed using full quantum-state information that… ▽ More Ground-state preparation is a critical task in quantum simulation and quantum computing, as it enables the study of correlated phases and the generation of entangled resource states. While measurement--feedback control has emerged as a promising route to state preparation, existing schemes either rely on handcrafted, task-specific policies or are designed using full quantum-state information that is unavailable in real experiments and becomes impractical for large many-body systems. Here we develop an adaptive measurement--feedback protocol based on reinforcement learning under partial observability. The controller uses only the history of experimentally accessible measurement outcomes to choose both the measurement operator and the feedback action in real time. To make training compatible with experiments, we introduce a stochastic terminal reward built from one-shot measurements of randomly sampled Hamiltonian components, avoiding unphysical full-state reconstruction while remaining an unbiased estimator of the target energy. We demonstrate the method by preparing ground states of the Bose--Hubbard model and by generating GHZ states, establishing a scalable and hardware-compatible route to quantum state preparation. △ Less

Submitted 11 June, 2026; originally announced June 2026.

Comments: 4 pages, 3 figures

Trapping 11,000 Atoms in a Tweezer Array Generated by a Single Metasurface

Authors: Yuqing Wang, Zhongchi Zhang, Tao Zhang, Yuxuan Liao, Hanteng Wang, Ye Tian, Binjie Ji, Yujia Wu, Luming Ma, Chen Qing, Chengshu Li, Wei Zhang, Yidong Huang, Wenjun Zhang, Xue Feng, Wenlan Chen, Hui Zhai

Abstract: The scalability of physical qubit numbers is a central challenge toward a universal fault-tolerant quantum computer. The inherent scalability of atom array quantum computers stems from the identical nature of atomic qubits, so the available qubit resource is primarily limited by the number of atoms that can be trapped and controlled. Here, we robustly trap 11,000 individual atoms in a tweezer arra… ▽ More The scalability of physical qubit numbers is a central challenge toward a universal fault-tolerant quantum computer. The inherent scalability of atom array quantum computers stems from the identical nature of atomic qubits, so the available qubit resource is primarily limited by the number of atoms that can be trapped and controlled. Here, we robustly trap 11,000 individual atoms in a tweezer array, thereby enabling the available qubit resource to reach the tens-of-thousands scale for the first time among all quantum computation platforms. This advance is enabled by a single metasurface, approximately 2 cm in diameter, that generates the entire tweezer array without the need for microscope objectives, thereby maximizing laser-power efficiency. The large aperture ensures a working distance of about 1.5 cm, allowing the metasurface to be placed outside the vacuum cell and avoiding the technical complications of in-vacuum operation. We further characterize the randomly loaded atom array using the statistical theory of percolation phase transitions. This work takes an important first step toward a quantum computer at the 10,000-qubit scale. △ Less

Submitted 1 June, 2026; originally announced June 2026.

A High-Contrast Bragg Atom Interferometer for Testing Continuous Spontaneous Localization

Authors: Huaiyu Zhu, Ju Liu, Tao Zhang, Qin Luo, Zhongkun Hu, Minkang Zhou

Abstract: The continuous spontaneous localization (CSL) model is one of the most promising approaches to address the wave function collapse problem in the measurement process of standard quantum mechanics. In this work, the effect of the CSL model on a Bragg atom interferometer was investigated. A Bragg interferometer achieving high fringe contrast of 99$\%$ has been demonstrated, maintaining this performan… ▽ More The continuous spontaneous localization (CSL) model is one of the most promising approaches to address the wave function collapse problem in the measurement process of standard quantum mechanics. In this work, the effect of the CSL model on a Bragg atom interferometer was investigated. A Bragg interferometer achieving high fringe contrast of 99$\%$ has been demonstrated, maintaining this performance level at interrogation time up to $T=60~\mathrm{ms}$. The primary factors responsible for fringe contrast loss in the atom interferometer were systematically analyzed and corrected. This improvement established a new upper limit of $λ_{\rm CSL}=1.27\times10^{-5}~\mathrm{s}^{-1}$ at $r_C=10^{-5}~\mathrm{m}$ for the CSL collapse rate, representing approximately 4 times enhancement over previous atom-interferometric constraints. △ Less

Submitted 26 May, 2026; originally announced May 2026.

Comments: 8 pages, 5 figures

Unified Flux Control Architecture for Fluxonium Qubits

Authors: Xianchuang Pan, Jiahui Wang, Tao Zhou, Yanbo Guo, Fei Wang, Ze Zhan, Liang Xiang, Zishuo Li, Lu Ma, Xizheng Ma, Huijuan Zhan, Tao Zhang, Kannan Lu, Xing Zhu, Guicheng Gong, Chunqing Deng, Tenghui Wang

Abstract: Control architectures that reduce hardware overhead while maintaining high-fidelity operations are essential for the continued scaling of superconducting quantum processors. Here we experimentally realize a unified control architecture for fluxonium qubits, in which both transverse ($XY$) and longitudinal ($Z$) operations are implemented through a single flux-control channel driven by a single arb… ▽ More Control architectures that reduce hardware overhead while maintaining high-fidelity operations are essential for the continued scaling of superconducting quantum processors. Here we experimentally realize a unified control architecture for fluxonium qubits, in which both transverse ($XY$) and longitudinal ($Z$) operations are implemented through a single flux-control channel driven by a single arbitrary waveform generator channel. This architecture imposes competing requirements on the shared control channel, which must simultaneously support low-frequency flux transmission for reset operations while strongly attenuating broadband noise near the qubit transition frequency. We address this challenge through frequency-selective cryogenic filtering together with compensated waveform synthesis that corrects the pulse distortion introduced by the filtered control line. Experimentally, this approach preserves coherence times above 100 $μ$s while enabling active reset with approximately 98% fidelity and 20-ns single-qubit gates with fidelities exceeding 99.99%. We further demonstrate FPGA-native instruction-level waveform synthesis based on reusable pulse primitives for unified flux control. These results establish unified flux control as a scalable architecture for fluxonium qubits that reduces control hardware overhead while preserving high-fidelity operation. △ Less

Submitted 28 May, 2026; v1 submitted 25 May, 2026; originally announced May 2026.

Comments: 13 pages, 7 figures

Imaginarity Resource Theory of Gaussian Quantum Channels

Authors: Ting Zhang, Jinchuan Hou, Xiaofei Qi

Abstract: Complex numbers play an indispensable role in quantum mechanics and quantum information, as validated by both theoretical analysis and experimental verification. Since quantum information processing inherently relies on quantum channels, the resource theory for quantum channels is equally fundamental to that for quantum states. In this paper, we propose two frameworks for quantifying the imaginari… ▽ More Complex numbers play an indispensable role in quantum mechanics and quantum information, as validated by both theoretical analysis and experimental verification. Since quantum information processing inherently relies on quantum channels, the resource theory for quantum channels is equally fundamental to that for quantum states. In this paper, we propose two frameworks for quantifying the imaginarity of Gaussian channels. The first framework regards all real superchannels as free superchannels. Within this setting, we introduce two concrete imaginarity measures for Gaussian channels: I_s^GC based on existing imaginarity measures of Gaussian states, and I_d^GC derived directly from the intrinsic parameters of Gaussian channels, which enjoys high computational simplicity. The second framework adopts only a proper subset of real superchannels as free superchannels. Under this framework, we put forward another imaginarity measure I_c^GC , which is fully determined by the inherent parameters of Gaussian channels and features continuity as well as tractable computation. As a practical application, we employ I_c^GC to investigate the dynamical behavior of Quantum Brownian Motion Gaussian channels throughout the entire evolutionary process. △ Less

Submitted 13 May, 2026; originally announced May 2026.

Correlations Between Quantum Battery Capacity and Quantum Resources for Two-qubit System

Authors: Yiding Wang, Xiaofen Huang, Tinggui Zhang

Abstract: We investigate the relationship between quantum battery capacity and quantum resources in a two-qubit system consisting of mutually coupled battery and charger subsystems. We find that the battery capacity decreases monotonically with the quantum entanglement, steering, Bell nonlocality and coherence, and peaks when these four quantum resources vanish. Moreover, we reveal the capacity gap between… ▽ More We investigate the relationship between quantum battery capacity and quantum resources in a two-qubit system consisting of mutually coupled battery and charger subsystems. We find that the battery capacity decreases monotonically with the quantum entanglement, steering, Bell nonlocality and coherence, and peaks when these four quantum resources vanish. Moreover, we reveal the capacity gap between the total system capacity and the sum of the battery and charger spin capacities, which is the residual battery capacity, and establish its positive correlation with entanglement. Furthermore, unlike the first four resources, although the battery capacity decreases monotonically with quantum imaginarity, its disappearance under system detuning does not guarantee a peak capacity, and this effect becomes more pronounced as the detuning increases. In contrast to the first five resources, the quantum state texture shows a positive correlation with battery capacity, but a negative correlation with entanglement, steering, Bell nonlocality, coherence, imaginarity, and residual battery capacity. These monotonic relationships are independent of the choice of system parameters. Our findings reveal the relationship between quantum battery capacity and quantum resources during the dynamic evolution of a quantum battery system, and advances the theory of quantum batteries and the development of quantum energy storage systems. △ Less

Submitted 11 May, 2026; originally announced May 2026.

Comments: 14 pages, 4 figures, 1 table

Journal ref: Advanced Quantum Technologies 9(4)e70289, 2026

Manipulation of diverse quantum correlations based on a hybrid optomagnomechanical system

Authors: Xiaomin Liu, Rongguo Yang, Jing Zhang, Tiancai Zhang

Abstract: Flexible manipulation of quantum correlation resources enables the implementation of diverse quantum tasks based on hybrid quantum networks, where atom-magnon and optomagnonic entanglements and steerings play important roles. In this work, we propose an effective scheme to generate and manipulate quantum entanglements and steerings based on a hybrid optomagnomechanical system, which is composed of… ▽ More Flexible manipulation of quantum correlation resources enables the implementation of diverse quantum tasks based on hybrid quantum networks, where atom-magnon and optomagnonic entanglements and steerings play important roles. In this work, we propose an effective scheme to generate and manipulate quantum entanglements and steerings based on a hybrid optomagnomechanical system, which is composed of a polarizer, an optical cavity with YIG bridge as one end, and an atomic ensemble in it. According to the results of the parameter dependence of various quantum correlations, we can selectively generate bipartite and genuine tripartite entanglements and deterministically manipulate the concrete situation of bipartite, multipartite steerings, and collective pentapartite steering, by adjusting the polarization direction of the driving laser and the Tavis-Cummings coupling strength. Our all-optical controlled scheme is flexible, convenient, compact, and experimentally feasible, because multiple coupling channels can be tuned simultaneously. This work provides a new perspective for implementing specialized quantum tasks, such as hierarchical ultra-secure multi-user quantum communications. △ Less

Submitted 25 April, 2026; originally announced April 2026.

Comments: 8 pages, 8 figures

AI-Enabled Decoding of Qubit Loss for Quantum Error-Correcting Codes

Authors: Yuqing Wang, Xiaotian Nie, Jiale Dai, Zhongyi Ni, Tao Zhang, Hui Zhai, Linghui Chen

Abstract: Qubit loss is a major source of error in quantum computation, as it invalidates the algebraic structure of the standard stabilizer formalism for quantum error-correcting codes. On the one hand, it complicates decoding; on the other hand, it introduces stochastic flicker patterns in stabilizers as a hallmark of qubit loss. Here, we develop an artificial-intelligence-enabled decoder based on a spati… ▽ More Qubit loss is a major source of error in quantum computation, as it invalidates the algebraic structure of the standard stabilizer formalism for quantum error-correcting codes. On the one hand, it complicates decoding; on the other hand, it introduces stochastic flicker patterns in stabilizers as a hallmark of qubit loss. Here, we develop an artificial-intelligence-enabled decoder based on a spatiotemporal Graph Neural Network (STGNN) architecture to extract spatial and temporal correlations from syndrome histories. Our decoder performs a dual-head task, simultaneously correcting standard Pauli errors and identifying the locations of qubit loss. Our decoder achieves significantly higher logical accuracy than both the traditional minimum-weight perfect matching (MWPM) algorithm and even delayed-erasure MWPM decoders that use qubit loss information from the final round as input. Our decoder can also identify more than 90% of loss locations after accumulating stabilizer measurements over the subsequent ten rounds, thereby facilitating qubit reinitialization, for instance, via the continuous loading technique on the atom array platform. For both tasks, our STGNN performs nearly identically to a modified version of AlphaQubit, but it employs a parallel input structure, giving it an advantage in inference time over modified AlphaQubit's recurrent input structure. This work provides a robust and scalable framework for correcting qubit loss errors, paving the way for more efficient fault-tolerant quantum computation. △ Less

Submitted 25 May, 2026; v1 submitted 15 April, 2026; originally announced April 2026.

An Algorithm for Fast Assembling Large-Scale Defect-Free Atom Arrays

Authors: Tao Zhang, Xiaodi Li, Hui Zhai, Linghui Chen

Abstract: It is widely believed that tens of thousands of physical qubits are needed to build a practically useful quantum computer. Atom arrays formed by optical tweezers are among the most promising platforms for achieving this goal, owing to the excellent scalability and mobility of atomic qubits. However, assembling a defect-free atom array with ~ 10^4 qubits remains algorithmically challenging, alongsi… ▽ More It is widely believed that tens of thousands of physical qubits are needed to build a practically useful quantum computer. Atom arrays formed by optical tweezers are among the most promising platforms for achieving this goal, owing to the excellent scalability and mobility of atomic qubits. However, assembling a defect-free atom array with ~ 10^4 qubits remains algorithmically challenging, alongside other hardware limitations. This is due to the computationally hard path-planning problems and the time-consuming generation of suffciently smooth trajectories for optical tweezer potentials by spatial light modulators (SLM). Here, we present a unified framework comprising two innovative components to fully address these algorithmic challenges: (1) a path-planning module that employs a supervised learning approach using a graph neural network combined with a modified auction decoder, and (2) a potential-generation module called the phase and profile-aware Weighted Gerchberg-Saxton algorithm. The inference time for the first module is nearly a size-independent constant overhead of ~ 5 ms, and the second module generates a potential frame with about 0.5 ms, a timescale shorter than the current commercial SLM refresh time. Altogether, our algorithm enables the assembly of an atom array with 10^4 qubits on a timescale much shorter than the typical vacuum lifetime of the trapped atoms. △ Less

Submitted 9 April, 2026; originally announced April 2026.

A Review of Variational Quantum Algorithms: Insights into Fault-Tolerant Quantum Computing

Authors: Zhirao Wang, Junxiang Huang, Runyu Ye, Qingyu Li, Qi-Ming Ding, Yiming Huang, Ting Zhang, Yumeng Zeng, Jianshuo Gao, Xiao Yuan, Yuan Yao

Abstract: Variational quantum algorithms (VQAs) have established themselves as a central computational paradigm in the Noisy Intermediate-Scale Quantum (NISQ) era. By coupling parameterized quantum circuits (PQCs) with classical optimization, they operate effectively under strict hardware limitations. However, as quantum architectures transition toward early fault-tolerant (EFT) and ultimate fault-tolerant… ▽ More Variational quantum algorithms (VQAs) have established themselves as a central computational paradigm in the Noisy Intermediate-Scale Quantum (NISQ) era. By coupling parameterized quantum circuits (PQCs) with classical optimization, they operate effectively under strict hardware limitations. However, as quantum architectures transition toward early fault-tolerant (EFT) and ultimate fault-tolerant (FT) regimes, the foundational principles and long-term viability of VQAs require systematic reassessment. This review offers an insightful analysis of VQAs and their progression toward the fault-tolerant regime. We deconstruct the core algorithmic framework by examining ansatz design and classical optimization strategies, including cost function formulation, gradient computation, and optimizer selection. Concurrently, we evaluate critical training bottlenecks, notably barren plateaus (BPs), alongside established mitigation strategies. The discussion then explores the EFT phase, detailing how the integration of quantum error mitigation and partial error correction can sustain algorithmic performance. Addressing the FT phase, we analyze the inherent challenges confronting current hybrid VQA models. Furthermore, we synthesize recent VQA applications across diverse domains, including many-body physics, quantum chemistry, machine learning, and mathematical optimization. Ultimately, this review outlines a theoretical roadmap for adapting quantum algorithms to future hardware generations, elucidating how variational principles can be systematically refined to maintain their relevance and efficiency within an error-corrected computational environment. △ Less

Submitted 9 April, 2026; originally announced April 2026.

Dynamics of Entanglement in Schwarzschild Black Holes

Authors: Fang Xie, Ying Yang, Tinggui Zhang, Xiaofen Huang

Abstract: To characterize the effect of Hawking radiation induced by the quantum atmosphere beyond the event horizon on entanglement, we employ concurrence as the entanglement measure for a bipartite mixed state and investigate its evolution with Hawking temperature. We find that the physically accessible concurrence decreases as the Hawking acceleration increases, whereas the physically inaccessible concur… ▽ More To characterize the effect of Hawking radiation induced by the quantum atmosphere beyond the event horizon on entanglement, we employ concurrence as the entanglement measure for a bipartite mixed state and investigate its evolution with Hawking temperature. We find that the physically accessible concurrence decreases as the Hawking acceleration increases, whereas the physically inaccessible concurrence exhibits the opposite behavior, increasing monotonically from zero. We further establish several trade-off relations on concurrence, revealing its distribution between physically accessible and inaccessible regions. Additionally, we study the dynamics of concurrence under three types of channel noise. The results indicate that the evolution of concurrence depends on the specific noise channel: unlike the phase damping channel, sudden death of concurrence occurs in both phase flip and bit flip channels, the concurrence exhibits a certain symmetry with respect to the noise parameter during its evolution under bit flip channel noise. △ Less

Submitted 6 April, 2026; originally announced April 2026.

Noise is not always detrimental: the capacity of quantum batteries is enhanced in black holes

Authors: Xukun Wang, Xiaofen Huang, Zhihao Ma, Shao-Ming Fei, Tinggui Zhang

Abstract: Quantum battery capacity, as a critical metric for quantifying energy storage and release in quantum systems, exhibits complex behaviors in curved spacetime and noisy environments. This study focuses on bipartite mixed state, aiming to explore the modulation of quantum battery capacity by Hawking radiation and environmental noise. We find a counterintuitive phenomenon that Hawking radiation can en… ▽ More Quantum battery capacity, as a critical metric for quantifying energy storage and release in quantum systems, exhibits complex behaviors in curved spacetime and noisy environments. This study focuses on bipartite mixed state, aiming to explore the modulation of quantum battery capacity by Hawking radiation and environmental noise. We find a counterintuitive phenomenon that Hawking radiation can enhance battery capacity, exerting a positive influence on energy storage, a result that stands in stark contrast to the detrimental effects typically associated with entanglement and coherence. When a quantum battery is simultaneously subjected to environmental noise and Hawking radiation, its capacity generally degrades, with the extent of degradation depending on the type of noise. The charging and discharging behaviors largely follow the same patterns observed in the noiseless scenario; however, under a bit flip channel with strong noise intensity, the charging-discharging pattern reverses. In the extreme case of maximum noise intensity, the capacity of the quantum battery under depolarizing noise tends to zero. The underlying physical mechanism lies in the fact that the bit flip channel disrupts the original population distribution of energy levels, thereby altering the average energy of the system and establishing a perturbative environment for bidirectional energy exchange. This differs fundamentally from the phase flip channel. These findings offer a new perspective for the theory of quantum batteries in noninertial reference frames. △ Less

Submitted 2 July, 2026; v1 submitted 6 April, 2026; originally announced April 2026.

1-Mbps Twin-Field Quantum Key Distribution over 200 km Using Independent Dissipative Kerr Solitons

Authors: Hao Dong, Tian-Jiao Zhang, Yan-Wei Chen, Wei Sun, Cong Jiang, Sanli Huang, Shuyi Li, Di Ma, Xiang-Bin Wang, Yang Liu, Junqiu Liu, Qiang Zhang, Jian-Wei Pan

Abstract: Twin-field quantum key distribution (TF-QKD) dramatically enhances the secure key rate (SKR) over inter-city distances through its square-root scaling. Further improvements in aggregate SKR can be achieved by wavelength-division multiplexing (WDM) of parallel QKD channels. However, direct implementation in TF-QKD poses significant challenges, as each wavelength channel requires an independent ultr… ▽ More Twin-field quantum key distribution (TF-QKD) dramatically enhances the secure key rate (SKR) over inter-city distances through its square-root scaling. Further improvements in aggregate SKR can be achieved by wavelength-division multiplexing (WDM) of parallel QKD channels. However, direct implementation in TF-QKD poses significant challenges, as each wavelength channel requires an independent ultra-stable seed laser, narrow-linewidth transmitters, and optical phase-locked loops (OPLLs), which are not easily scalable. Here, we circumvent these limitations by employing two independent, integrated dissipative Kerr soliton (DKS) microcombs at Alice and Bob as multi-wavelength sources. High-visibility single-photon interference across all wavelength channels is achieved by stabilizing the frequencies of every comb line - requiring only the stabilization of the pump wavelength and repetition rates of the two microcombs. Based on this architecture, we perform a full TF-QKD experiment using the sending-or-not-sending protocol, achieving a total SKR of 1.57 Mbps over 201.1 km of fiber using 16 DWDM channels. This result represents more than an order-of-magnitude enhancement compared with single-wavelength TF-QKD at the same distance. Given that a single DKS comb can support over 100 coherent lines across the C-band, this approach offers a scalable pathway toward high-rate quantum key distribution over inter-city distances. △ Less

Submitted 31 March, 2026; originally announced April 2026.

Comments: 26 pages, 11 figures

A Flexible GKP-State-Embedded Fault-Tolerant Quantum Computation Configuration Based on a Three-Dimensional Cluster State

Authors: Peilin Du, Jing Zhang, Tiancai Zhang, Rongguo Yang, Kui Liu, Jiangrui Gao

Abstract: The integration of diverse quantum resources and the exploitation of more degrees of freedom provide key operational flexibility for universal fault-tolerant quantum computation. In this work, we propose a flexible Gottesman-Kitaev-Preskill-state-embedded fault-tolerant quantum computation architecture based on a three-dimensional cluster state constructed in polarization, frequency, and orbital a… ▽ More The integration of diverse quantum resources and the exploitation of more degrees of freedom provide key operational flexibility for universal fault-tolerant quantum computation. In this work, we propose a flexible Gottesman-Kitaev-Preskill-state-embedded fault-tolerant quantum computation architecture based on a three-dimensional cluster state constructed in polarization, frequency, and orbital angular momentum domains. Specifically, we design optical entanglement generators to produce three diverse entangled pairs, and subsequently construct a three-dimensional cluster state via a beam-splitter network with several time delays. Furthermore, we present a partially squeezed surface-GKP code to achieve fault-tolerant quantum computation and ultimately find the optimal choice of implementing the squeezing gate to give the best fault-tolerant performance (the fault-tolerant squeezing threshold is 11.5 dB). Our scheme is flexible, scalable, and experimentally feasible, providing versatile options for future optical fault-tolerant quantum computation architecture. △ Less

Submitted 19 March, 2026; originally announced March 2026.

Comments: 8 pages,6 figures

Quantum discord of mixed states under noisy channels in the curved spacetime

Authors: Yuxuan Xiong, Zhiling Pi, Tinggui Zhang, Xiaofen Huang

Abstract: We focus our attention on two-qubit mixed states as initial states, and apply the geometric measure of quantum discord to investigate quantum discord properties in the background of a Schwarzschild black hole under phase damping, phase flip and bit flip channels, respectively. Several analytical complementary relationships based on quantum discords for bipartite subsystems are proposed. For the th… ▽ More We focus our attention on two-qubit mixed states as initial states, and apply the geometric measure of quantum discord to investigate quantum discord properties in the background of a Schwarzschild black hole under phase damping, phase flip and bit flip channels, respectively. Several analytical complementary relationships based on quantum discords for bipartite subsystems are proposed. For the three channel noises, the behaviors of discords are similar, the accessible discords always degrade as the Hawking acceleration rising, but sudden death never occurs, while the inaccessible discords increase from zero monotonically. Interestingly, in the case of the bit flip channel and phase flip channel, the discords perform symmetrically with the decay probability rising. △ Less

Submitted 24 February, 2026; originally announced February 2026.

Journal ref: Eur. Phys. J. C (2026) 86:317

Quantum coherence of mixed states under noisy channels in noninertial frames

Authors: Tangrui Liao, Junhao Yang, Tinggui Zhang, Xiaofen Huang

Abstract: We focus our attention on tripartite mixed states as initial states, and apply coherence concurrence to investigate quantum coherence properties in the background of a Schwarzschild black hole under phase damping, phase flip and bit flip channels, respectively. Several analytic complementary relationships based on coherence concurrence for tripartite subsystems are proposed. In the case of the bit… ▽ More We focus our attention on tripartite mixed states as initial states, and apply coherence concurrence to investigate quantum coherence properties in the background of a Schwarzschild black hole under phase damping, phase flip and bit flip channels, respectively. Several analytic complementary relationships based on coherence concurrence for tripartite subsystems are proposed. In the case of the bit flip channel, the behavior of the coherence concurrence is similar to the one of the phase damping channel, the accessible coherence concurrence always degrades as the Hawking acceleration rising, but sudden death never occurs, while the inaccessible coherence increases from zero monotonically. Interestingly, the coherence concurrence is decreasing at first and then increasing as the decay probability rising under phase flip channel. Unlike the case of tripartite pure states, the coherence concurrence of mixed state with X shape is equal to $l_1$ -norm of coherence. △ Less

Submitted 24 February, 2026; originally announced February 2026.

Journal ref: Results in Physics 70 (2025) 108169

Reducing the Complexity of Matrix Multiplication by Quantum Computing

Authors: Jiaqi Yao, Tianjian Huang, Tonghe Zhang, Ding Liu

Abstract: Matrix multiplication is a fundamental operation in compute-intensive tasks and a key component of modern quantum acceleration frameworks. Here we present a quantum matrix multiplication algorithm based on quantum kernels (QKMM), achieving an elementary gate complexity of \(O(N^2\log_2N)\), with amplitude encoding overhead explicitly included and without assuming a QRAM oracle. This scaling is asy… ▽ More Matrix multiplication is a fundamental operation in compute-intensive tasks and a key component of modern quantum acceleration frameworks. Here we present a quantum matrix multiplication algorithm based on quantum kernels (QKMM), achieving an elementary gate complexity of \(O(N^2\log_2N)\), with amplitude encoding overhead explicitly included and without assuming a QRAM oracle. This scaling is asymptotically lower than that of the best-known classical matrix multiplication algorithm \(O(N^{2.371339})\). Building upon QKMM, we establish a family of quantum linear algebra operators, including Quantum Vector Inner Product (V${\scriptstyle 2}$V), Quantum Vector-Matrix Multiplication (V${\scriptstyle 2}$M), QKMM (M${\scriptstyle 2}$M), Quantum One-to-Many Matrix Multiplication(O${\scriptstyle 2}$M) and Quantum Sequential Matrix Multiplication (SMM), providing a unified framework from vector operations to parallel and sequential matrix transformations. Through noiseless simulations, realistic noise modelling and experiments on a superconducting quantum processor, we systematically characterize the numerical accuracy, resource requirements and hardware execution limits of this operator framework. Furthermore, we integrate SMM into deep neural-network inference, enabling intermediate features to propagate coherently across layers without repeated measurement and re-encoding. These results establish a pathway from quantum circuit-level algorithm design to end-to-end coherent computation, providing a quantum computing framework for matrix-centric compute-intensive applications. △ Less

Submitted 20 August, 2026; v1 submitted 5 February, 2026; originally announced February 2026.

Practical continuous-variable quantum key distribution using dynamic digital signal processing: security proof and experimental demonstration

Authors: Lu Fan, Zhengyu Li, Sheng Liu, Xuesong Xu, Tianyu Zhang, Jiale Mi, Dong Wang, Dechao Zhang, Han Li, Song Yu, Yichen Zhang

Abstract: Digital signal processing technology has paved the way for the realization of high-speed continuous-variable quantum key distribution systems. However, existing security proofs are limited to static digital signal processing algorithms, while practical systems rely on dynamic multiple-input multiple-output algorithms to compensate for time-varying channel impairments. Our analysis reveals that the… ▽ More Digital signal processing technology has paved the way for the realization of high-speed continuous-variable quantum key distribution systems. However, existing security proofs are limited to static digital signal processing algorithms, while practical systems rely on dynamic multiple-input multiple-output algorithms to compensate for time-varying channel impairments. Our analysis reveals that the conventional dynamic algorithm, due to its non-unitary nature, systematically underestimates the excess noise, which in turn leads to security issues and the generation of insecure keys. To close this gap, we propose a secure algorithm model, mapping the dynamic algorithm to an equivalent physical optical model whose security can be rigorously assessed. Simulations illustrate the algorithm's non-unitary property and provide a quantitative analysis of the excess noise underestimation caused by the conventional algorithm. We further experimentally validate the necessity of the proposed modeling for dynamic digital signal processing, achieving a secret key rate of 14.4 Mbps based on estimated excess noise of 0.07 shot noise unit; whereas the conventional algorithm would have dangerously overestimated the key rate to 28.2 Mbps with noise of 0.008 shot noise unit. This work provides the essential security framework for dynamic digital signal processing, overcoming a critical impediment for the development of high-performance continuous-variable quantum key distribution systems. △ Less

Submitted 4 February, 2026; originally announced February 2026.

Comments: 10 pages, 8 figures

Tripartite quantum steering in Schwarzschild spacetime

Authors: Guang-Wei Mi, Xiaofen Huang, Tinggui Zhang

Abstract: We investigate the effects of Hawking radiation on quantum steering and steering asymmetry in a tripartite system embedded in Schwarzschild spacetime. All tripartite steering types were classified,comprising three "1 to 2" and three "2 to 1" steering cases. Through a systematic analysis of all physically relevant scenarios (including accessible and inaccessible modes), we classify three canonical… ▽ More We investigate the effects of Hawking radiation on quantum steering and steering asymmetry in a tripartite system embedded in Schwarzschild spacetime. All tripartite steering types were classified,comprising three "1 to 2" and three "2 to 1" steering cases. Through a systematic analysis of all physically relevant scenarios (including accessible and inaccessible modes), we classify three canonical scenarios with one, two and three physically accessible modes. In the scenario of three physically accessible modes, Hawking radiation disrupts quantum steering, with the maximum steering asymmetry during the two-way steering to one-way steering transition precisely demarcating the phase boundary between these regimes. For two physically accessible modes, Hawking radiation exhibits dual behavior: enhancing the steering from Alice and Bob to anti-Charlie under certain parameters while suppressing it under others, while net strengthening other steering types. When considering one physically accessible mode, the Hawking effect of the black hole significantly enhances quantum steering. These findings provide new insights into quantum correlations in curved spacetime and establish observable signatures of Hawking effects in quantum steering phenomena. △ Less

Submitted 31 January, 2026; originally announced February 2026.

Comments: 15pages, 3 figures

Journal ref: Eur. Phys. J. C (2026) 86:75

Volcano Architecture for Scalable Quantum Processor Units

Authors: Dong-Qi Ma, Qing-Xuan Jie, Ya-Dong Hu, Wen-Yi Zhu, Yi-Chen Zhang, Hong-Jie Fan, Xiao-Kang Zhong, Guang-Jie Chen, Yan-Lei Zhang, Tian-Yang Zhang, Xi-Feng Ren, Liang Chen, Zhu-Bo Wang, Guang-Can Guo, Chang-Ling Zou

Abstract: Quantum information processing platforms based on array of matter qubits, such as neutral atoms, trapped ions, and quantum dots, face significant challenges in scalable addressing and readout as system sizes increase. Here, we propose the "Volcano" architecture that establishes a new quantum processing unit implementation method based on optical channel mapping on a arbitrarily arranged static qub… ▽ More Quantum information processing platforms based on array of matter qubits, such as neutral atoms, trapped ions, and quantum dots, face significant challenges in scalable addressing and readout as system sizes increase. Here, we propose the "Volcano" architecture that establishes a new quantum processing unit implementation method based on optical channel mapping on a arbitrarily arranged static qubit array. To support the feasibility of Volcano architecture, we show a proof-of-principle demonstration by employing a photonic chip that leverages custom-designed three-dimensional waveguide structures to transform one-dimensional beam arrays into arbitrary two-dimensional output patterns matching qubit array geometries. We demonstrate parallel and independent control of 49-channel with negligible crosstalk and high uniformity. This architecture addresses the challenges in scaling up quantum processors, including both the classical link for parallel qubit control and the quantum link for efficient photon collection, and holds the potential for interfacing with neutral atom arrays and trapped ion crystals, as well as networking of heterogeneous quantum systems. △ Less

Submitted 31 December, 2025; originally announced December 2025.

Comments: Accepted to Science China Physics, Mechanics & Astronomy. 12 pages, 6 figures

Journal ref: Sci. China Phys. Mech. Astron. 69, 220314 (2026)

Information-Scrambling-Enhanced Quantum Sensing Beyond the Standard Quantum Limit

Authors: Yangyang Ge, Haoyu Zhou, Wen Zheng, Xiang-Min Yu, Wei Fang, Zhenchuan Zhang, Wanli Huang, Xiang Deng, Haoyang Cai, Xianke Li, Kun Zhou, Hanxin Che, Tao Zhang, Lichang Ji, Yu Zhang, Jie Zhao, Shao-Xiong Li, Xinsheng Tan, Yang Yu

Abstract: Quantum sensing promises measurement precision beyond classical limits, but its practical realization is often hindered by decoherence and the challenges of generating and stabilizing entanglement in large-scale systems. Here, we experimentally demonstrate a scalable, scrambling-enhanced quantum sensing protocol, referred to as butterfly metrology, implemented on a cross-shaped superconducting qua… ▽ More Quantum sensing promises measurement precision beyond classical limits, but its practical realization is often hindered by decoherence and the challenges of generating and stabilizing entanglement in large-scale systems. Here, we experimentally demonstrate a scalable, scrambling-enhanced quantum sensing protocol, referred to as butterfly metrology, implemented on a cross-shaped superconducting quantum processor. By harnessing quantum information scrambling, the protocol converts local interactions into delocalized metrologically useful correlations, enabling robust signal amplification through interference of the scrambled and polarized quantum states. We validate the time-reversal ability via Loschmidt echo measurements and quantify the information scrambling through out-of-time-ordered correlators, establishing the essential quantum resources of our protocol. Our measurements reveal that the sensing sensitivity surpasses the standard quantum limit (SQL) with increasing qubit number, reaching 3.78 in a 9-qubit configuration, compared to the SQL of 3.0. The scheme further exhibits inherent robustness to coherent control errors and probed signal noise. This work demonstrates a readily scalable path toward practical quantum sensing advantages with prevalent experimental platforms. △ Less

Submitted 24 December, 2025; originally announced December 2025.

Trade-off relations and enhancement protocol of quantum battery capacities in multipartite systems

Authors: Yiding Wang, Xiaofen Huang, Shao-Ming Fei, Tinggui Zhang

Abstract: First, we investigate the trade-off relations of quantum battery capacities in two-qubit system. We find that the sum of subsystem battery capacity is governed by the total system capacity, with this trade-off relation persisting for a class of Hamiltonians, including Ising, XX, XXZ and XXX models. Then building on this relation, we define residual battery capacity for general quantum states and e… ▽ More First, we investigate the trade-off relations of quantum battery capacities in two-qubit system. We find that the sum of subsystem battery capacity is governed by the total system capacity, with this trade-off relation persisting for a class of Hamiltonians, including Ising, XX, XXZ and XXX models. Then building on this relation, we define residual battery capacity for general quantum states and establish coherent/incoherent components of subsystem battery capacity. Furthermore, we introduce the protocol to guide the selection of appropriate incoherent unitary operations for enhancing subsystem battery capacity in specific scenarios, along with a sufficient condition for achieving subsystem capacity gain through unitary operation. Numerical examples validate the feasibility of the incoherent operation protocol. Additionally, for the three-qubit system, we also established a set of theories and results parallel to those for two-qubit case. Finally, we determine the minimum time required to enhance subsystem battery capacity via a single incoherent operation in our protocol. Our findings contribute to the development of quantum battery theory and quantum energy storage systems. △ Less

Submitted 16 December, 2025; originally announced December 2025.

Comments: 16 pages, 3 figures, 1 table

Journal ref: Frontiers of Physics 21(7) 073201 (2026)

Direct Generation of an Array with 78400 Optical Tweezers Using a Single Metasurface

Authors: Yuqing Wang, Yuxuan Liao, Tao Zhang, Ye Tian, Yujia Wu, Wenjun Zhang, Wei Zhang, Yidong Huang, Hui Zhai, Wenlan Chen, Xue Feng, Zhongchi Zhang

Abstract: Scalability remains a major challenge in building practical fault-tolerant quantum computers. Currently, the largest number of qubits achieved across leading quantum platforms ranges from hundreds to thousands. In atom arrays, scalability is primarily constrained by the capacity to generate large numbers of optical tweezers, and conventional techniques using acousto-optic deflectors or spatial lig… ▽ More Scalability remains a major challenge in building practical fault-tolerant quantum computers. Currently, the largest number of qubits achieved across leading quantum platforms ranges from hundreds to thousands. In atom arrays, scalability is primarily constrained by the capacity to generate large numbers of optical tweezers, and conventional techniques using acousto-optic deflectors or spatial light modulators struggle to produce arrays much beyond $\sim 10,000$ tweezers. Moreover, these methods require additional microscope objectives to focus the light into micrometer-sized spots, which further complicates system integration and scalability. Here, we demonstrate the experimental generation of an optical tweezer array containing $280\times 280$ spots using a metasurface, nearly an order of magnitude more than most existing systems. The metasurface leverages a large number of subwavelength phase-control pixels to engineer the wavefront of the incident light, enabling both large-scale tweezer generation and direct focusing into micron-scale spots without the need for a microscope. This result shifts the scalability bottleneck for atom arrays from the tweezer generation hardware to the available laser power. Furthermore, the array shows excellent intensity uniformity exceeding $90\%$, making it suitable for homogeneous single-atom loading and paving the way for trapping arrays of more than $10,000$ atoms in the near future. △ Less

Submitted 8 December, 2025; originally announced December 2025.

Comments: 5 pages, 4 figures. Chinese Physics Letters, accepted

Journal ref: Chin. Phys. Lett., 43(1), 010606(2026)

The evolution of quantum battery capacity of GHZ-like states under Markovian channels

Authors: Hui Liu, Tinggui Zhang

Abstract: Quantum battery has enormous potential for development, and quantum battery capacity is an important indicator of quantum battery. In this work, we mainly study the evolution of quantum battery capacity of GHZ state and GHZ-like states under Markovian channels in the tripartite system. We find that under the depolarizing channel and bit-phase flip channel, the battery capacity shows a brief sudden… ▽ More Quantum battery has enormous potential for development, and quantum battery capacity is an important indicator of quantum battery. In this work, we mainly study the evolution of quantum battery capacity of GHZ state and GHZ-like states under Markovian channels in the tripartite system. We find that under the depolarizing channel and bit-phase flip channel, the battery capacity shows a brief sudden death of the capacity. And we also find that under the dephasing channel, the battery capacity gradually decreases and tends to a constant, that is, the frozen capacity. We show that the battery capacity monotonically decreases for GHZ state under the amplitude damping channel on the first subsystem. And we study the variation of capacity under the Markovian channels n times on the first subsystem using the GHZ state. We can observe that under the amplitude damping and dephasing channels, the battery capacity decreases and tends to a constant, i.e. frozen capacity, and the larger n, the earlier this phenomenon occurs. We also investigate the evolution of capacity under three independent same type Markovian channels. We have also conducted corresponding research on GHZ-like states. △ Less

Submitted 21 November, 2025; originally announced November 2025.

Comments: 21 pages, 10 figures

Journal ref: Quantum Information Processing 24:352 (2025)

Scalable protocol to coherence estimation from scarce data: Theory and experiment

Authors: Qi-Ming Ding, Ting Zhang, Hui Li, Da-Jian Zhang

Abstract: Key quantum features like coherence are the fundamental resources enabling quantum advantages and ascertaining their presence in quantum systems is crucial for developing quantum technologies. This task, however, faces severe challenges in the noisy intermediate-scale quantum era. On one hand, experimental data are typically scarce, rendering full state reconstruction infeasible. On the other hand… ▽ More Key quantum features like coherence are the fundamental resources enabling quantum advantages and ascertaining their presence in quantum systems is crucial for developing quantum technologies. This task, however, faces severe challenges in the noisy intermediate-scale quantum era. On one hand, experimental data are typically scarce, rendering full state reconstruction infeasible. On the other hand, these features are usually quantified by highly nonlinear functionals that elude efficient estimations via existing methods. In this work, we propose a scalable protocol for estimating coherence from scarce data and further experimentally demonstrate its practical utility. The key innovation here is to relax the potentially NP-hard coherence estimation problem into a computationally efficient optimization. This renders the computational cost in our protocol insensitive to the system size, in sharp contrast to the exponential growth in traditional methods. This work opens a novel route toward estimating coherence of large-scale quantum systems under data-scarce conditions. △ Less

Submitted 24 October, 2025; originally announced October 2025.

Comments: 10 pages, 6 figures

Journal ref: Physical Review A 113 (3), 032444 (2026)

Quantumness near the Schwarzschild black hole based on W-state

Authors: Guang-Wei Mi, Xiaofen Huang, Shao-Ming Fei, Tinggui Zhang

Abstract: We investigate certain quantumness in the vicinity of the Schwarzschild black hole by utilizing the W state. We explore the influence of the Hawking effect on the l_1-norm of quantum coherence, the first-order coherence (FOC), the concurrence-fill (CF) and the global concurrence (GC) in Schwarzschild black hole, for systems with one, two and three physically accessible modes. We conclude that the… ▽ More We investigate certain quantumness in the vicinity of the Schwarzschild black hole by utilizing the W state. We explore the influence of the Hawking effect on the l_1-norm of quantum coherence, the first-order coherence (FOC), the concurrence-fill (CF) and the global concurrence (GC) in Schwarzschild black hole, for systems with one, two and three physically accessible modes. We conclude that the Hawking effect of the black hole not only disrupts but also enhance the quantum entanglement, while destroying the quantum coherence for systems with three physically accessible modes. For systems with one or two physically accessible modes, the Hawking effect exerts a positive influence on quantum coherence and quantum entanglement. Moreover, we study the influence of both the Hawking effect and environmental noise (AD channels) on l_1-norm of quantum coherence, FOC, CF and GC. It is demonstrated that for systems with three physically accessible modes, the Hawking effect of the black hole disrupts quantum coherence but exerts a positive influence on quantum entanglement under the AD channels. △ Less

Submitted 13 October, 2025; originally announced October 2025.

Comments: 10 pages, 6 figures

Journal ref: Annalen der Physik,2025.10.1002

Three-dimensional optical characterization of magnetostrictive deformation in magnomechanical systems

Authors: Xiaomin Liu, Jing Zhang, Jie Li, Rongguo Yang, Jiangrui Gao, Tiancai Zhang

Abstract: Magnomechanical systems with YIG spheres have been proven to be an ideal system for studying magnomechanically induced transparency, dynamical backaction, and rich nonlinear effects, such as the magnon-phonon cross-Kerr effect. Accurate characterization of the magnetostriction induced deformation displacement is important as it can be used for, e.g., estimating the magnon excitation number and the… ▽ More Magnomechanical systems with YIG spheres have been proven to be an ideal system for studying magnomechanically induced transparency, dynamical backaction, and rich nonlinear effects, such as the magnon-phonon cross-Kerr effect. Accurate characterization of the magnetostriction induced deformation displacement is important as it can be used for, e.g., estimating the magnon excitation number and the strength of the dynamical backaction. Here we propose an optical approach for detecting the magnetostrictive deformation of a YIG sphere in three dimensions (3Ds) with high precision. It is based on the deformation induced spatial high-order modes of the scattered field, postselection, and balanced homodyne detection. With feasible parameters, we show that the measurement precision of the deformation in $x$, $y$, and $z$ directions can reach the picometer level. We further reveal the advantages of our scheme using a higher-order probe beam and balanced homodyne detection by means of quantum and classical Fisher information. The real-time and high-precision measurement of the YIG sphere's deformation in 3Ds can be used to determinate specific mechanical modes, characterize the magnomechanical dynamical backaction and the 3D cooling of the mechanical vibration, and thus finds a wide range of applications in magnomechanics. △ Less

Submitted 9 October, 2025; originally announced October 2025.

Derandomised tensor product gap amplification for quantum Hamiltonians

Authors: Thiago Bergamaschi, Tony Metger, Thomas Vidick, Tina Zhang

Abstract: The quantum PCP conjecture asks whether it is QMA-hard to distinguish between high- and low-energy Hamiltonians even when the gap between "high" and "low" energy is large (constant). A natural proof strategy is gap amplification: start from the fact that high- and low-energy Hamiltonians are hard to distinguish if the gap is small (inverse polynomial) and amplify the Hamiltonians to increase the e… ▽ More The quantum PCP conjecture asks whether it is QMA-hard to distinguish between high- and low-energy Hamiltonians even when the gap between "high" and "low" energy is large (constant). A natural proof strategy is gap amplification: start from the fact that high- and low-energy Hamiltonians are hard to distinguish if the gap is small (inverse polynomial) and amplify the Hamiltonians to increase the energy gap while preserving hardness. Such a gap amplification procedure is at the heart of Dinur's proof of the classical PCP theorem. In this work, following Dinur's model, we introduce a new quantum gap amplification procedure for Hamiltonians which uses random walks on expander graphs to derandomise (subsample the terms of) the tensor product amplification of a Hamiltonian. Curiously, our analysis relies on a new technique inspired by quantum de Finetti theorems, which have previously been used to rule out certain approaches to the quantum PCP conjecture. △ Less

Submitted 1 October, 2025; originally announced October 2025.

Comments: 42 pages

Computational Monogamy of Entanglement and Non-Interactive Quantum Key Distribution

Authors: Alex B. Grilo, Giulio Malavolta, Michael Walter, Tianwei Zhang

Abstract: Quantum key distribution (QKD) enables Alice and Bob to exchange a secret key over a public, untrusted quantum channel. Compared to classical key exchange, QKD achieves everlasting security: after the protocol execution the key is secure against adversaries that can do unbounded computations. On the flip side, while classical key exchange can be achieved non-interactively (with two simultaneous me… ▽ More Quantum key distribution (QKD) enables Alice and Bob to exchange a secret key over a public, untrusted quantum channel. Compared to classical key exchange, QKD achieves everlasting security: after the protocol execution the key is secure against adversaries that can do unbounded computations. On the flip side, while classical key exchange can be achieved non-interactively (with two simultaneous messages between Alice and Bob), no non-interactive protocol is known that provides everlasting security, even using quantum information. In this work, we make progress on this problem. Our main technical contribution is a computational variant of the celebrated monogamy of entanglement game, where the secret is only computationally hidden from the players, rather than information-theoretically. In these settings, we prove a negligible bound on the maximal winning probability over all strategies. As a direct application, we obtain a non-interactive (simultaneous message) QKD protocol from any post-quantum classical non-interactive key exchange, which satisfies everlastingly secure assuming Alice and Bob agree on the same key. The protocol only uses EPR pairs and standard and Hadamard basis measurements, making it suitable for near-term quantum hardware. We also propose how to convert this protocol into a two-round protocol that satisfies the standard notion of everlasting security. Finally, we prove a no-go theorem which establishes that (in contrast to the case of ordinary multi-round QKD) entanglement is necessary for non-interactive QKD, i.e., the messages sent by Alice and Bob cannot both be unentangled with their respective quantum memories if the protocol is to be everlastingly secure. △ Less

Submitted 1 October, 2025; originally announced October 2025.

Comments: 32 pages

Journal ref: Theory of Cryptography (TCC 2025). Lecture Notes in Computer Science, vol 16270

Directly observing relativistic Bohmian mechanics

Authors: Yun-Fei Wang, Hui Wang, Tong Zhang, Yi-Teng Ye, Xiao-Yu Wang, Chao-Yang Lu, Jian-Wei Pan

Abstract: Bohmian mechanics, also referred to as the de Broglie-Bohm pilot-wave theory, represents a deterministic and nonlocal interpretation of quantum mechanics. Since its origination in 1927, despite many attempts, reconciling it with relativistic theory and verification of its relativistic effects have remained elusive. Here, we report a direct observation of relativistic characteristics of Bohmian mec… ▽ More Bohmian mechanics, also referred to as the de Broglie-Bohm pilot-wave theory, represents a deterministic and nonlocal interpretation of quantum mechanics. Since its origination in 1927, despite many attempts, reconciling it with relativistic theory and verification of its relativistic effects have remained elusive. Here, we report a direct observation of relativistic characteristics of Bohmian mechanics. We reconstruct the relativistic Bohmian trajectories of single photons utilizing weak measurement techniques in a double-slit interferometer, unveiling a fundamental aspect of relativistic Bohmian mechanics. We investigate the effective squared mass density of single photons, revealing its negative values in the destructive regions -- a phenomenon directly links to the tachyonic behavior in relativistic Bohmian mechanics. The continuity equations given by both the Klein-Gordon equation and Schrödinger's equation are experimentally examined. Our result indicates that within the framework of relativity, the conservation of energy holds true, whereas the conservation of particle number for a free scalar field no longer holds. The emergence of previously unobserved phenomena in the extensively studied double-slit experiment are enabled by Bohmian mechanics, while conversely, these experimental outcomes offer unambiguous evidence of the long-sought-after relativistic features within Bohmian mechanics. △ Less

Submitted 15 September, 2025; originally announced September 2025.

Femtojoule-per-operation photonic computer for the subset sum problem

Authors: Tian-Yu Zhang, Xiao-Yun Xu, Wen-Hao Zhou, Xiao-Wei Wang, Chu-Han Wang, Yi-Jun Chang, Ying-Yue Yang, Jie Ma, Ka-Di Zhu, Xian-Min Jin

Abstract: Energy-efficient computing is becoming increasingly important in the information era. However, electronic computers with von Neumann architecture can hardly meet the challenge due to the inevitable energy-intensive data movement, especially when tackling computationally hard problems or complicated tasks. Here, we experimentally demonstrate an energy-efficient photonic computer that solves intract… ▽ More Energy-efficient computing is becoming increasingly important in the information era. However, electronic computers with von Neumann architecture can hardly meet the challenge due to the inevitable energy-intensive data movement, especially when tackling computationally hard problems or complicated tasks. Here, we experimentally demonstrate an energy-efficient photonic computer that solves intractable subset sum problem (SSP) by making use of the extremely low energy level of photons (~10^(-19) J) and a time-of-flight storage technique. We show that the energy consumption of the photonic computer maintains no larger than 10^(-15) J per operation at a reasonably large problem size N=33, and it consumes 10^(8) times less energy than the most energy-efficient supercomputer for a medium-scale problem. In addition, when the photonic computer is applied to deal with real-life problems that involves iterative computation of the SSP, the photonic advantage in energy consumption is further enhanced and massive energy can be saved. Our results indicate the superior competitiveness of the photonic computer in the energy costs of complex computation, opening a possible path to green computing. △ Less

Submitted 24 August, 2025; originally announced August 2025.

A convergent sum-of-squares hierarchy for compiled nonlocal games

Authors: David Cui, Chirag Falor, Anand Natarajan, Tina Zhang

Abstract: We continue the line of work initiated by Kalai et al. (STOC '23), studying "compiled" nonlocal games played between a classical verifier and a single quantum prover, with cryptography simulating the spatial separation between the players. The central open question in this area is to understand the soundness of this compiler against quantum strategies, and apart from results for specific games, al… ▽ More We continue the line of work initiated by Kalai et al. (STOC '23), studying "compiled" nonlocal games played between a classical verifier and a single quantum prover, with cryptography simulating the spatial separation between the players. The central open question in this area is to understand the soundness of this compiler against quantum strategies, and apart from results for specific games, all that is known is the recent "qualitative" result of Kulpe et al. (STOC '25) showing that the success probability of a quantum prover in the compiled game is bounded by the game's quantum commuting-operator value in the limit as the cryptographic security parameter goes to infinity. In this work, we make progress towards a quantitative understanding of quantum soundness for general games, by giving a concrete framework to bound the quantum value of compiled nonlocal games. Building on the result of Kulpe et al. together with the notion of "nice" sum-of-squares certificates, introduced by Natarajan and Zhang (FOCS '23) to bound the value of the compiled CHSH game, we extend the niceness framework and construct a hierarchy of semidefinite programs that searches exclusively over nice certificates. We show that this hierarchy converges to the optimal quantum value of the game. Additionally, we present a transformation to make any degree-1 sum-of-squares certificate nice. This approach provides a systematic method to reproduce all known bounds for special classes of games together with Kulpe et al.'s bound for general games from the same framework. △ Less

Submitted 23 July, 2025; originally announced July 2025.

Comments: 36 pages. We refer to Klep, Paddock, Renou, Schmidt, Tendick, Xu, and Zhao for an independent parallel work on the same topic

Efficient Implementation of a Single-Qutrit Gate Set via Coherent Control

Authors: Xiang-Min Yu, Xiang Deng, Wen Zheng, Wei Xin, Tao Zhang, Hanxin Che, Kun Zhou, Haoyu Zhou, Yangyang Ge, Zhenchuan Zhang, Wanli Huang, Haoyang Cai, Xianke Li, Jie Zhao, Xinsheng Tan, Yu Zhang, Shao-Xiong Li, Yang Yu

Abstract: Qutrits offer the potential for enhanced quantum computation by exploiting an enlarged Hilbert space. However, the synthesis of high-fidelity and fast qutrit gates, particularly for single qutrits, remains an ongoing challenge, as it involves overcoming intrinsic constraints in quantum platforms. Here, we develop a novel framework for the efficient implementation of a single-qutrit gate set via co… ▽ More Qutrits offer the potential for enhanced quantum computation by exploiting an enlarged Hilbert space. However, the synthesis of high-fidelity and fast qutrit gates, particularly for single qutrits, remains an ongoing challenge, as it involves overcoming intrinsic constraints in quantum platforms. Here, we develop a novel framework for the efficient implementation of a single-qutrit gate set via coherent control, leveraging SU(3) dynamics while obviating platform-specific constraints such as those arising from the selection rule. As a proof-of-principle demonstration, we realize 35-ns qutrit Hadamard and X gates using a superconducting transmon, achieving an average fidelity of 99.5\%, as verified by randomized benchmarking. We further demonstrate two paradigmatic quantum circuits, which can be naturally extended to scalable qudit algorithms for phase estimation and parity check. In addition, we propose an SU(3)-based decomposition strategy for an arbitrary single-qutrit gate and numerically demonstrate its substantial efficiency improvement over conventional SU(2)-based protocols. By addressing the challenge of efficiently implementing single-qutrit gates, our protocol paves the way for realizing high-performance qutrit processors in diverse quantum platforms. △ Less

Submitted 14 June, 2026; v1 submitted 9 July, 2025; originally announced July 2025.

Journal ref: Phys. Rev. Lett. 136, 230803 (2026)

Notes on detection and measurement of quantum coherence

Authors: Yiding Wang, Tinggui Zhang

Abstract: Quantum coherence is one of the most basic characteristics of quantum mechanics. Here we give some methods to detect and measure quantum coherence. Firstly, we propose a coherence criterion without full quantum state tomography based on partial transposition. Moreover, we present a coherent nonlinear detection strategy from witnesses, in which we find that for some coherent states, normal witness… ▽ More Quantum coherence is one of the most basic characteristics of quantum mechanics. Here we give some methods to detect and measure quantum coherence. Firstly, we propose a coherence criterion without full quantum state tomography based on partial transposition. Moreover, we present a coherent nonlinear detection strategy from witnesses, in which we find that for some coherent states, normal witness detection fails but our nonlinear detection succeeds. In addition, we prove that when the nonlinear detection on the two copies of the coherent state fails, the nonlinear detection on the three copies may be successful. Finally, due to the difficulty in calculating robustness of coherence for general states, we introduce a lower bound for coherent robustness based on the witness operator, and after comparing our lower bound with the currently known lower bound, one show that our lower bound is better. Coherence is believed to play a crucial role in quantum information tasks, making the detection and quantization of coherence particularly significant. Therefore, these results help to open up new avenues for advancement in quantum theory. △ Less

Submitted 17 June, 2025; originally announced June 2025.

Comments: 11 pages, 5 figures

Journal ref: J. Phys. A: Math. Theor. 58 245303 (2025)

Improving Quantum Battery Capacity in Tripartite Quantum Systems by Local Projective Measurements

Authors: Yiding Wang, Hui Liu, Shao-Ming Fei, Tinggui Zhang

Abstract: The impact of local von Neumann measurements on quantum battery capacity is investigated in tripartite quantum systems. Two measurement-based protocols are proposed and the concept of optimal local projective operators is introduced. Specifically, explicit analytical expressions are derived for the protocols when applied to general three-qubit X-states. Furthermore, the negative effects of white n… ▽ More The impact of local von Neumann measurements on quantum battery capacity is investigated in tripartite quantum systems. Two measurement-based protocols are proposed and the concept of optimal local projective operators is introduced. Specifically, explicit analytical expressions are derived for the protocols when applied to general three-qubit X-states. Furthermore, the negative effects of white noise and dephasing noise on quantum battery capacity are analyzed, proving that optimal local projective operators can improve the robustness of subsystem and total system capacity against both noise types for the general tripartite X-state. The performance of different schemes in capacity enhancement are numerically validated through detailed examples and it is found that these optimized operators can effectively enhance both subsystem and total system battery capacity. The results indicate that the local von Neumann measurement is a powerful tool to enhance the battery capacity in multipartite quantum systems. △ Less

Submitted 17 June, 2025; originally announced June 2025.

Comments: 12 pages, 5 figures

Journal ref: Adv. Quantum Technol. 2025, 2500095

Tunable Hybrid-Mode Coupler Enabling Strong Interactions between Transmons at Centimeter-Scale Distance

Authors: Jianwen Xu, Xiang Deng, Wen Zheng, Wenchang Yan, Tao Zhang, Zhenchuan Zhang, Wanli Huang, Xiaoyu Xia, Xudong Liao, Yu Zhang, Jie Zhao, Shaoxiong Li, Xinsheng Tan, Dong Lan, Yang Yu

Abstract: The transmon, a fabrication-friendly superconducting qubit, remains a leading candidate for scalable quantum computing. Recent advances in tunable couplers have accelerated progress toward high-performance quantum processors. However, extending coherent interactions beyond millimeter scales to enhance quantum connectivity presents a critical challenge. Here, we introduce a hybrid-mode coupler expl… ▽ More The transmon, a fabrication-friendly superconducting qubit, remains a leading candidate for scalable quantum computing. Recent advances in tunable couplers have accelerated progress toward high-performance quantum processors. However, extending coherent interactions beyond millimeter scales to enhance quantum connectivity presents a critical challenge. Here, we introduce a hybrid-mode coupler exploiting resonator-transmon hybridization to simultaneously engineer the two lowest-frequency mode, enabling high-contrast coupling between centimeter-scale transmons. For a 1-cm coupler, our framework predicts flux-tunable $XX$ and $ZZ$ coupling strengths reaching 23 MHz and 100 MHz, with modulation contrasts exceeding $10^2$ and $10^4$, respectively, demonstrating quantitative agreement with an effective two-channel model. This work provides an efficient pathway to mitigate the inherent connectivity constraints imposed by short-range interactions, enabling transmon-based architectures compatible with hardware-efficient quantum tasks. △ Less

Submitted 12 November, 2025; v1 submitted 16 June, 2025; originally announced June 2025.

Comments: 12 pages, 7 figures

Journal ref: Phys. Rev. Applied 25, 014016 (2026)

High-Sensitivity Fiber Interferometer for Gravitational Phase Shift Measurement on Entangled States

Authors: Eleonora Polini, Piotr Chruściel, Georgi Dvali, Christopher Hilweg, Begüm Kabagöz, Dorotea Macri, Thomas Mieling, Thomas Morling, Eric Oelker, Elisabeth Steininger, Xinghui Yin, Haocun Yu, Sebastian Zell, Tongxuan Zhang, Nergis Mavalvala, Philip Walther

Abstract: In this contribution, we describe the status of our experiment aimed at measuring the gravitationally induced phase shift on path-entangled photons. We use a kilometer-scale fiber interferometer whose arms are vertically displaced in the Earth gravitational potential, allowing photons propagating at different heights to accumulate different phases. To date, this is the first experiment to measure… ▽ More In this contribution, we describe the status of our experiment aimed at measuring the gravitationally induced phase shift on path-entangled photons. We use a kilometer-scale fiber interferometer whose arms are vertically displaced in the Earth gravitational potential, allowing photons propagating at different heights to accumulate different phases. To date, this is the first experiment to measure this effect on massless particles, thereby experimentally combining general relativity and quantum mechanics. △ Less

Submitted 25 June, 2025; v1 submitted 11 June, 2025; originally announced June 2025.

Comments: This submission contains scientific errors and was not approved by all co-authors

Can Theoretical Physics Research Benefit from Language Agents?

Authors: Sirui Lu, Zhijing Jin, Terry Jingchen Zhang, Pavel Kos, J. Ignacio Cirac, Bernhard Schölkopf

Abstract: Large Language Models (LLMs) are rapidly advancing across diverse domains, yet their application in theoretical physics remains inadequate. While current models show competence in mathematical reasoning and code generation, we identify critical gaps in physical intuition, constraint satisfaction, and reliable reasoning that cannot be addressed through prompting alone. Physics demands approximation… ▽ More Large Language Models (LLMs) are rapidly advancing across diverse domains, yet their application in theoretical physics remains inadequate. While current models show competence in mathematical reasoning and code generation, we identify critical gaps in physical intuition, constraint satisfaction, and reliable reasoning that cannot be addressed through prompting alone. Physics demands approximation judgment, symmetry exploitation, and physical grounding that require AI agents specifically trained on physics reasoning patterns and equipped with physics-aware verification tools. We argue that LLM would require such domain-specialized training and tooling to be useful in real-world for physics research. We envision physics-specialized AI agents that seamlessly handle multimodal data, propose physically consistent hypotheses, and autonomously verify theoretical results. Realizing this vision requires developing physics-specific training datasets, reward signals that capture physical reasoning quality, and verification frameworks encoding fundamental principles. We call for collaborative efforts between physics and AI communities to build the specialized infrastructure necessary for AI-driven scientific discovery. △ Less

Submitted 12 March, 2026; v1 submitted 6 June, 2025; originally announced June 2025.

Comments: 8+2 pages + references

Optically accessible high-finesse millimeter-wave resonator for cavity quantum electrodynamics with atom arrays

Authors: Tony Zhang, Michelle Wu, Sam R. Cohen, Lin Xin, Debadri Das, Kevin K. S. Multani, Nolan Peard, Anne-Marie Valente-Feliciano, Paul B. Welander, Amir H. Safavi-Naeini, Emilio A. Nanni, Monika Schleier-Smith

Abstract: Cavity quantum electrodynamics (QED) is a powerful tool in quantum science, enabling preparation of non-classical states of light and scalable entanglement of many atoms coupled to a single field mode. While the most coherent atom-photon interactions have been achieved using superconducting millimeter-wave cavities coupled to Rydberg atoms, these platforms so far lack the optical access required f… ▽ More Cavity quantum electrodynamics (QED) is a powerful tool in quantum science, enabling preparation of non-classical states of light and scalable entanglement of many atoms coupled to a single field mode. While the most coherent atom-photon interactions have been achieved using superconducting millimeter-wave cavities coupled to Rydberg atoms, these platforms so far lack the optical access required for trapping and addressing individual atomic qubits. We present a millimeter-wave Fabry-Pérot cavity with finesse $5.8(1) \times 10^7$ at a temperature of 1 K providing generous transverse optical access (numerical aperture 0.56). Conflicting goals of strong atom-photon coupling and optical access motivate a near-confocal geometry. Close to confocality, however, post-paraxial corrections to the cavity spectrum introduce unexpected degeneracies between transverse modes, leading to excess cavity loss. Modeling these corrections allows for tuning the cavity geometry to evade this loss, producing a high finesse that will enable cavity QED experiments with trapped atoms deep in the strong coupling regime. △ Less

Submitted 6 June, 2025; originally announced June 2025.

Comments: 6 pages (4 figures) + 21 pages of supplemental material (9 figures)

Observation of Near-Critical Kibble-Zurek Scaling in Rydberg Atom Arrays

Authors: Tao Zhang, Hanteng Wang, Wenjun Zhang, Yuqing Wang, Angrui Du, Ziqi Li, Yujia Wu, Chengshu Li, Jiazhong Hu, Hui Zhai, Wenlan Chen

Abstract: The Kibble-Zurek scaling reveals the universal dynamics when a system is linearly ramped across a symmetry-breaking phase transition. However, in reality, inevitable finite-size effects or symmetrybreaking perturbations can often smear out the critical point and render the phase transition into a smooth crossover. In this letter, we show experimentally that the precise Kibble-Zurek scaling can be… ▽ More The Kibble-Zurek scaling reveals the universal dynamics when a system is linearly ramped across a symmetry-breaking phase transition. However, in reality, inevitable finite-size effects or symmetrybreaking perturbations can often smear out the critical point and render the phase transition into a smooth crossover. In this letter, we show experimentally that the precise Kibble-Zurek scaling can be retained in the near-critical crossover regime, not necessarily crossing the critical point strictly. The key ingredient to achieving this near-critical Kibble-Zurek scaling is that the system size and the symmetry-breaking field must be appropriately scaled following the variation of ramping speeds. The experiment is performed in a reconfigurable Rydberg atom array platform, where the Rydberg blockade effect induces a Z2 symmetry-breaking transition. The atom array platform enables precise control of the system size and the zigzag geometry as a symmetry-breaking field. Therefore, we can demonstrate notable differences in the precision of the Kibble-Zurek scaling with or without properly scaling the system size and the zigzag geometry. Our results strengthen the Kibble-Zurek scaling as an increasingly valuable tool for investigating phase transition in quantum simulation platforms. △ Less

Submitted 12 May, 2025; originally announced May 2025.

Comments: 16 pages, 11 figures

Journal ref: Phys. Rev. Lett. 135, 093403 (2025)

On-chip Non-Hermitian Cavity Quantum Electrodynamics

Authors: Yan Chen, Xudong Wang, Jin Li, Rongbin Su, Kaili Xiong, Xueshi Li, Ying Yu, Tao Zhang, Kexun Wu, Xiao Li, Jiawei Wang, Jiaxiang Zhang, Jin Liu, Tian Jiang

Abstract: Exceptional points (EPs) promise revolutionary control over quantum light-matter interactions. Here, we experimentally demonstrate flexible and reversible engineering of quantum vacuum fluctuation in an integrated microcavity supporting chiral Eps. We develop a hybrid lithium niobate (LN)-GaAs quantum photonic platform, seamlessly combining high-quality quantum emitters, a low-loss photonic circui… ▽ More Exceptional points (EPs) promise revolutionary control over quantum light-matter interactions. Here, we experimentally demonstrate flexible and reversible engineering of quantum vacuum fluctuation in an integrated microcavity supporting chiral Eps. We develop a hybrid lithium niobate (LN)-GaAs quantum photonic platform, seamlessly combining high-quality quantum emitters, a low-loss photonic circuit, efficient electro-optic (EO) effect, and local strain actuator in a single device. Chiral EPs are implemented by dynamically tuning the coupling between the modes associated with a micro-ring resonator, resulting in anomalous spontaneous emission dynamic with a 7-fold modulation of the lifetime (120 ps to 850 ps). Meanwhile, we reshape single-photon spectra via cavity local density of states (LDOS) engineering and generate non-Lorentzian spectral profiles: squared-Lorentzian, Fano-like, and EP-induced transparency (EPIT), a suppression of emission at zero detuning. This work unveils exotic cavity quantum electrodynamics (cQED) effects unique to EPs and establishes a universal paradigm for non-Hermitian quantum photonics. △ Less

Submitted 1 May, 2025; originally announced May 2025.

Quantifying quantum-state texture

Authors: Yiding Wang, Hui Liu, Tinggui Zhang

Abstract: Quantum-state texture is a newly recognized quantum resource that has garnered attention with the advancement of quantum theory. In this work, we introduce several potential quantum-state texture measure schemes and check whether they satisfy the three fundamental conditions required for a valid quantum-state texture measure. Specifically, the measure induced by the l_1-norm serves as a vital tool… ▽ More Quantum-state texture is a newly recognized quantum resource that has garnered attention with the advancement of quantum theory. In this work, we introduce several potential quantum-state texture measure schemes and check whether they satisfy the three fundamental conditions required for a valid quantum-state texture measure. Specifically, the measure induced by the l_1-norm serves as a vital tool for quantifying coherence, but we prove that it cannot be used to quantify quantum state texture. Furthermore, we show that while relative entropy and robustness meet three fundamental conditions, they are not optimal for quantifying quantum-state texture. Fortunately, we still find that there are several measures that can be used as the measure standard of quantum-state texture. Among them, the trace distance measure and the geometric measure are two good measurement schemes. In addition, the two measures based on Uhlmann's fidelity are experimentally friendly and can serve as an ideal definition of quantum-state texture measures in non-equilibrium situations. All these researches on quantum-state texture measure theory can enrich the resource theory framework of quantum-state texture. △ Less

Submitted 25 April, 2025; originally announced April 2025.

Comments: 9 pages, 1 figure

Journal ref: Phys. Rev. A 111, 042427 (2025)