npj Quantum Information最新文献

Machine learning message-passing for the scalable decoding of QLDPC codes QLDPC码可扩展解码的机器学习消息传递

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-17 DOI: 10.1038/s41534-025-01033-w

Arshpreet Singh Maan, Alexandru Paler

引用次数: 0

Trade-off between gradient measurement efficiency and expressivity in deep quantum neural networks 深度量子神经网络中梯度测量效率与表达性的权衡

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-17 DOI: 10.1038/s41534-025-01036-7

Koki Chinzei, Shinichiro Yamano, Quoc Hoan Tran, Yasuhiro Endo, Hirotaka Oshima

{"title":"Trade-off between gradient measurement efficiency and expressivity in deep quantum neural networks","authors":"Koki Chinzei, Shinichiro Yamano, Quoc Hoan Tran, Yasuhiro Endo, Hirotaka Oshima","doi":"10.1038/s41534-025-01036-7","DOIUrl":"https://doi.org/10.1038/s41534-025-01036-7","url":null,"abstract":"Quantum neural networks (QNNs) require an efficient training algorithm to achieve practical quantum advantages. A promising approach is gradient-based optimization, where gradients are estimated by quantum measurements. However, QNNs currently lack general quantum algorithms for efficiently measuring gradients, which limits their scalability. To elucidate the fundamental limits and potentials of efficient gradient estimation, we rigorously prove a trade-off between gradient measurement efficiency (the mean number of simultaneously measurable gradient components) and expressivity in deep QNNs. This trade-off indicates that more expressive QNNs require higher measurement costs per parameter for gradient estimation, while reducing QNN expressivity to suit a given task can increase gradient measurement efficiency. We further propose a general QNN ansatz called the stabilizer-logical product ansatz (SLPA), which achieves the trade-off upper bound by exploiting the symmetric structure of the quantum circuit. Numerical experiments show that the SLPA drastically reduces the sample complexity needed for training while maintaining accuracy and trainability compared to well-designed circuits based on the parameter-shift method.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"7 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144083202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantum annealing for combinatorial optimization: a benchmarking study 组合优化的量子退火：基准研究

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-16 DOI: 10.1038/s41534-025-01020-1

Seongmin Kim, Sang-Woo Ahn, In-Saeng Suh, Alexander W. Dowling, Eungkyu Lee, Tengfei Luo

{"title":"Quantum annealing for combinatorial optimization: a benchmarking study","authors":"Seongmin Kim, Sang-Woo Ahn, In-Saeng Suh, Alexander W. Dowling, Eungkyu Lee, Tengfei Luo","doi":"10.1038/s41534-025-01020-1","DOIUrl":"https://doi.org/10.1038/s41534-025-01020-1","url":null,"abstract":"Quantum annealing (QA) has the potential to significantly improve solution quality and reduce time complexity in solving combinatorial optimization problems compared to classical optimization methods. However, due to the limited number of qubits and their connectivity, the QA hardware did not show such an advantage over classical methods in past benchmarking studies. Recent advancements in QA with more than 5000 qubits, enhanced qubit connectivity, and the hybrid architecture promise to realize the quantum advantage. Here, we use a quantum annealer with state-of-the-art techniques and benchmark its performance against classical solvers. To compare their performance, we solve over 50 optimization problem instances represented by large and dense Hamiltonian matrices using quantum and classical solvers. The results demonstrate that a state-of-the-art quantum solver has higher accuracy (~0.013%) and a significantly faster problem-solving time (~6561×) than the best classical solver. Our results highlight the advantages of leveraging QA over classical counterparts, particularly in hybrid configurations, for achieving high accuracy and substantially reduced problem solving time in large-scale real-world optimization problems.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"18 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Discovery of entanglement generation by elastic collision to realise the original Einstein-Podolsky-Rosen thought experiment 发现弹性碰撞产生纠缠，实现最初的爱因斯坦-波多尔斯基-罗森思想实验

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-14 DOI: 10.1038/s41534-025-01028-7

Roman Schnabel

引用次数: 0

Low-overhead defect-adaptive surface code with bandage-like super-stabilizers 带有绷带式超稳定器的低开销缺陷自适应表面代码

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-12 DOI: 10.1038/s41534-025-01023-y

Zuolin Wei, Tan He, Yangsen Ye, Dachao Wu, Yiming Zhang, Youwei Zhao, Weiping Lin, He-Liang Huang, Xiaobo Zhu, Jian-Wei Pan

{"title":"Low-overhead defect-adaptive surface code with bandage-like super-stabilizers","authors":"Zuolin Wei, Tan He, Yangsen Ye, Dachao Wu, Yiming Zhang, Youwei Zhao, Weiping Lin, He-Liang Huang, Xiaobo Zhu, Jian-Wei Pan","doi":"10.1038/s41534-025-01023-y","DOIUrl":"https://doi.org/10.1038/s41534-025-01023-y","url":null,"abstract":"To make practical quantum algorithms work, large-scale quantum processors protected by error-correcting codes are required to resist noise and ensure reliable computational outcomes. However, a major challenge arises from defects in processor fabrication, as well as occasional losses or cosmic rays during the computing process, all of which can lead to qubit malfunctions and disrupt error-correcting codes’ normal operations. In this context, we introduce an automatic adapter to implement the surface code on defective lattices. Unlike previous approaches, this adapter leverages newly proposed bandage-like super-stabilizers to save more qubits when defects are clustered, thus enhancing the code distance and reducing super-stabilizer weight. For instance, in comparison with earlier methods, with a code size of 27 and a random defect rate of 2%, the disabled qubits decrease by 1/3, and the average preserved code distance increases by 63%. This demonstrates a significant reduction in overhead when handling defects using our approach, and this advantage amplifies with increasing processor size and defect rates. Our work presents a low-overhead, automated solution to the challenge of adapting the surface code to defects, an essential step towards scaling up the construction of large-scale quantum computers for practical applications.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"35 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143940438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Critical behavior of Fredenhagen-Marcu string order parameters at topological phase transitions with emergent higher-form symmetries 具有突现高形式对称性的拓扑相变中Fredenhagen-Marcu弦序参数的临界行为

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-09 DOI: 10.1038/s41534-025-01030-z

Wen-Tao Xu, Frank Pollmann, Michael Knap

引用次数: 0

Experimental demonstration of long distance quantum communication with independent heralded single photon sources 独立预告单光子源远距离量子通信的实验演示

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-08 DOI: 10.1038/s41534-025-01025-w

Xiao-Hai Zhan, Zhen-Qiu Zhong, Jian-Yu Ma, Shuang Wang, Zhen-Qiang Yin, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han

{"title":"Experimental demonstration of long distance quantum communication with independent heralded single photon sources","authors":"Xiao-Hai Zhan, Zhen-Qiu Zhong, Jian-Yu Ma, Shuang Wang, Zhen-Qiang Yin, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han","doi":"10.1038/s41534-025-01025-w","DOIUrl":"https://doi.org/10.1038/s41534-025-01025-w","url":null,"abstract":"Hong-Ou-Mandel interference is essential for various quantum communication protocols, including quantum teleportation, entanglement swapping, and measurement-device-independent (MDI) quantum key distribution (QKD). A significant challenge is producing single photons that remain indistinguishable over long distances. Time jitter introduced in synchronization between remote nodes reduces temporal overlap, making photons no longer indistinguishable. To mitigate this effect, previous solutions are forced to increase the temporal overlap, typically by using narrowband filtering strategies to extend photon coherence time. However, this dramatically decreases photon rates, making them impractical for real-life applications. Here we address this dilemma by employing common laser pulses to generate intrinsically synchronized single photons, eliminating the need for extended coherence time. Without compromising photon indistinguishability, we achieved a four-fold coincidence count rate more than two orders of magnitude higher than previous methods over 50 kilometers of fiber transmission. This breakthrough enabled the implementation of MDI-QKD with passive decoy states, demonstrating the viability of our approach.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"228 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143920380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Unveiling quantum steering by quantum-classical uncertainty complementarity 量子经典不确定性互补性揭示量子导向

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-08 DOI: 10.1038/s41534-025-01017-w

Kuan-Yi Lee, Jhen-Dong Lin, Karel Lemr, Antonín Černoch, Adam Miranowicz, Franco Nori, Huan-Yu Ku, Yueh-Nan Chen

{"title":"Unveiling quantum steering by quantum-classical uncertainty complementarity","authors":"Kuan-Yi Lee, Jhen-Dong Lin, Karel Lemr, Antonín Černoch, Adam Miranowicz, Franco Nori, Huan-Yu Ku, Yueh-Nan Chen","doi":"10.1038/s41534-025-01017-w","DOIUrl":"https://doi.org/10.1038/s41534-025-01017-w","url":null,"abstract":"One of the remarkable aspects of quantum steering is its ability to violate local uncertainty complementarity relations. In this vein of study, various steering witnesses have been developed. Here, we introduce a novel complementarity relation between the system’s quantum and classical uncertainties corresponding to the distillable coherence and the von Neumann entropy, respectively. We show that the proposed complementarity relation is tighter than the entropic uncertainty relation (EUR). Leveraging this result, we propose a steering witness that is more efficient than the EUR. From the operational perspective, the steering witness quantifies the amount of extra distillable coherence facilitated by quantum steerability. Notably, the proposed steering witness serves as a full entanglement measure for pure bipartite states–an ability that the EUR lacks. We also experimentally validate such a property through a photonic system. Furthermore, a deeper connection to the uncertainty principle is revealed by showcasing the steering-induced distillable coherence can quantify measurement incompatibility and quantum steerability under genuine incoherent operations. Our work establishes a clear quantitative and operational link between coherence and steering, which are vital resources of quantum technologies, and underscores our efforts in bridging the uncertainty principle with quantum coherence.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"7 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143920381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Digital reconstruction of squeezed light for quantum information processing 量子信息处理中压缩光的数字重构

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-03 DOI: 10.1038/s41534-025-01018-9

Huy Q. Nguyen, Ivan Derkach, Adnan A. E. Hajomer, Hou-Man Chin, Akash nag Oruganti, Ulrik L. Andersen, Vladyslav Usenko, Tobias Gehring

{"title":"Digital reconstruction of squeezed light for quantum information processing","authors":"Huy Q. Nguyen, Ivan Derkach, Adnan A. E. Hajomer, Hou-Man Chin, Akash nag Oruganti, Ulrik L. Andersen, Vladyslav Usenko, Tobias Gehring","doi":"10.1038/s41534-025-01018-9","DOIUrl":"https://doi.org/10.1038/s41534-025-01018-9","url":null,"abstract":"Squeezed light plays a vital role in quantum information processing. However, its highly sensitive nature presents significant practical challenges, particularly in remote detection, which traditionally requires complex systems such as active phase locking, clock synchronization, and polarization control. Here, we propose and demonstrate an asynchronous detection method for squeezed light eliminating the need for these complex systems. By employing radio-frequency heterodyne detection with a locally generated local oscillator and applying a series of digital unitary transformations, we successfully reconstruct squeezed states of light. We validate our approach in two key applications: the distribution of squeezed light over a 10 km fiber channel, and passive continuous-variables quantum key distribution based on squeezed vacuum states between two labs connected via deployed fiber. This demonstrates a practical digital reconstruction method for squeezed light, opening new avenues for practical distributed quantum sensing networks and high-performance, long-distance quantum communication using squeezed states.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"15 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143901380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Variational quantum algorithm for enhanced continuous variable optical phase sensing 增强连续可变光学相位传感的变分量子算法

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-05-02 DOI: 10.1038/s41534-024-00947-1

Jens A. H. Nielsen, Mateusz J. Kicinski, Tummas N. Arge, Kannan Vijayadharan, Jonathan Foldager, Johannes Borregaard, Johannes Jakob Meyer, Jonas S. Neergaard-Nielsen, Tobias Gehring, Ulrik L. Andersen

{"title":"Variational quantum algorithm for enhanced continuous variable optical phase sensing","authors":"Jens A. H. Nielsen, Mateusz J. Kicinski, Tummas N. Arge, Kannan Vijayadharan, Jonathan Foldager, Johannes Borregaard, Johannes Jakob Meyer, Jonas S. Neergaard-Nielsen, Tobias Gehring, Ulrik L. Andersen","doi":"10.1038/s41534-024-00947-1","DOIUrl":"https://doi.org/10.1038/s41534-024-00947-1","url":null,"abstract":"Variational quantum algorithms (VQAs) are hybrid quantum-classical approaches used for tackling a wide range of problems on noisy intermediate-scale quantum (NISQ) devices. Testing these algorithms on relevant hardware is crucial to investigate the effect of noise and imperfections and to assess their practical value. Here, we implement a variational algorithm designed for optimized parameter estimation on a continuous variable platform based on squeezed light, a key component for high-precision optical phase estimation. We investigate the ability of the algorithm to identify the optimal metrology process, including the optimization of the probe state and measurement strategy for small-angle optical phase sensing. Two different optimization strategies are employed, the first being a gradient descent optimizer using Gaussian parameter shift rules to estimate the gradient of the cost function directly from the measurements. The second strategy involves a gradient-free Bayesian optimizer, fine-tuning the system using the same cost function and trained on the data acquired through the gradient-dependent algorithm. We find that both algorithms can steer the experiment towards the optimal metrology process. However, they find minima not predicted by our theoretical model, demonstrating the strength of variational algorithms in modelling complex noise environments, a non-trivial task.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"111 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143898085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0