npj Quantum Information最新文献

Optimization complexity and resource minimization of emitter-based photonic graph state generation protocols 基于发射体的光子图状态生成协议的优化、复杂性和资源最小化

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-07-01 DOI: 10.1038/s41534-025-01056-3

Evangelia Takou, Edwin Barnes, Sophia E. Economou

{"title":"Optimization complexity and resource minimization of emitter-based photonic graph state generation protocols","authors":"Evangelia Takou, Edwin Barnes, Sophia E. Economou","doi":"10.1038/s41534-025-01056-3","DOIUrl":"https://doi.org/10.1038/s41534-025-01056-3","url":null,"abstract":"Photonic graph states are important for measurement- and fusion-based quantum computing, quantum networks, and sensing. They can in principle be generated deterministically by using emitters to create the requisite entanglement. Finding ways to minimize the number of entangling gates between emitters and understanding the overall optimization complexity of such protocols is crucial for practical implementations. Here, we address these issues using graph theory concepts. We develop optimizers that minimize the number of entangling gates, reducing them by up to 75% compared to naive schemes for moderately sized random graphs. While the complexity of optimizing emitter-emitter CNOT counts is likely NP-hard, we are able to develop heuristics based on strong connections between graph transformations and the optimization of stabilizer circuits. These patterns allow us to process large graphs and still achieve a reduction of up to 66% in emitter CNOTs, without relying on subtle metrics such as edge density. We find the optimal emission orderings and circuits to prepare unencoded and encoded repeater graph states of any size, achieving global minimization of emitter and CNOT resources despite the average NP-hardness of both optimization problems. We further study the locally equivalent orbit of graphs. Although enumerating orbits is #P complete for arbitrary graphs, we analytically calculate the size of the orbit of repeater graphs and find a procedure to generate the orbit for any repeater size. Finally, we inspect the entangling gate cost of preparing any graph from a given orbit and show that we can achieve the same optimal CNOT count across the orbit.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"1 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144521131","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 key distribution overcoming practical correlated intensity fluctuations 克服实际相关强度波动的量子密钥分布

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-07-01 DOI: 10.1038/s41534-025-01059-0

Jia-Xuan Li, Feng-Yu Lu, Ze-Hao Wang, Víctor Zapatero, Marcos Curty, Shuang Wang, Zhen-Qiang Yin, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han

引用次数: 0

Four-qubit variational algorithms in silicon photonics with integrated entangled photon sources 集成纠缠光子源硅光子学中的四量子位变分算法

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-07-01 DOI: 10.1038/s41534-025-01061-6

Alessio Baldazzi, Matteo Sanna, Massimo Borghi, Stefano Azzini, Lorenzo Pavesi

引用次数: 0

Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier 相敏放大器增强高速连续可变量子密钥分配的实验论证

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-17 DOI: 10.1038/s41534-025-01060-7

Jinpeng Liao, Zhirong Chen, Jintao Wang, Hao Xiao, Xiaojie Guo, Zhaohui Li, Dawei Wang

{"title":"Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier","authors":"Jinpeng Liao, Zhirong Chen, Jintao Wang, Hao Xiao, Xiaojie Guo, Zhaohui Li, Dawei Wang","doi":"10.1038/s41534-025-01060-7","DOIUrl":"https://doi.org/10.1038/s41534-025-01060-7","url":null,"abstract":"The type of system employing continuous variables, such as light field quadrature for signal modulation, is an important branch for quantum key distribution. Achieving a high key rate using quantum key distribution technology is beneficial for realizing more frequent key updates or enabling one-time pad encryption for high-speed communication tasks. However, the deficiencies of typical large-bandwidth balanced photodetectors prevent the continuous variable quantum key distribution from matching the speed of state-of-the-art classical optical communications. Previous attempts to improve the key rate have focused on designing and manufacturing high-speed balanced photodetectors. It is well known that phase-sensitive amplifiers also improve the performance of balanced photodetectors and thus the performance of key distribution, but the concept remains purely theoretical. Here, for the first time, we experimentally demonstrate a high-speed continuous-variable quantum key distribution operating with a 10 GHz balanced photodetector enhanced by phase-sensitive amplification and detection. A conjugated multi-mode continuous variable protocol is used to accommodate the phase-sensitive operations. The optical amplifier offers a 10 dB increase in the photodetector’s clearance (quantum noise over electrical noise) and improves the detection efficiency from 72% to 96%, thus enabling an overall 248.9 Mb/s key distribution rate through a 16.7 km field-deployed optical fiber.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"14 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312214","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

Revising the quantum work fluctuation framework to encompass energy conservation 修正量子功涨落框架以包含能量守恒

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-16 DOI: 10.1038/s41534-025-01053-6

Giulia Rubino, Karen V. Hovhannisyan, Paul Skrzypczyk

{"title":"Revising the quantum work fluctuation framework to encompass energy conservation","authors":"Giulia Rubino, Karen V. Hovhannisyan, Paul Skrzypczyk","doi":"10.1038/s41534-025-01053-6","DOIUrl":"https://doi.org/10.1038/s41534-025-01053-6","url":null,"abstract":"Work is a process-based quantity, and its measurement typically requires interaction with a measuring device multiple times. While classical systems allow for non-invasive and accurate measurements, quantum systems present unique challenges due to the influence of the measuring device on the final value of work. As recent studies have shown, among these challenges is the impossibility of formulating a universal definition of work that respects energy conservation for coherent quantum systems and is compatible with the Jarzynski equality—a fluctuation relation linking the equilibrium free energy difference to the non-equilibrium work. Here, we overcome this challenge by introducing a genuinely quantum, positive correction to the Jarzynski equality stemming from imposing energy conservation. When sufficiently large, this correction forces quantum work to violate the second law more often. Moreover, we construct modified two-point measurement (TPM) schemes for work, along with circuit implementations for them. These measurement schemes correctly certify energy conservation and remain consistent with our quantum-corrected fluctuation relation.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"12 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144296019","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

Symmetric Clifford twirling for cost-optimal quantum error mitigation in early FTQC regime 早期FTQC中成本最优量子误差缓解的对称Clifford旋转

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-16 DOI: 10.1038/s41534-025-01050-9

Kento Tsubouchi, Yosuke Mitsuhashi, Kunal Sharma, Nobuyuki Yoshioka

引用次数: 0

Robust microwave-optical photon conversion using cavity modes strongly hybridized with a color center ensemble 利用腔模式与色中心系综强杂化的鲁棒微波光学光子转换

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-16 DOI: 10.1038/s41534-025-01055-4

M. Khalifa, P. S. Kirwin, Jeff F. Young, J. Salfi

引用次数: 0

Quantum algorithms for matrix geometric means 矩阵几何均值的量子算法

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-13 DOI: 10.1038/s41534-025-00973-7

Nana Liu, Qisheng Wang, Mark M. Wilde, Zhicheng Zhang

引用次数: 0

Deterministic steady-state subradiance within a single-excitation basis 在单激励基础上的确定性稳态子辐射

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-10 DOI: 10.1038/s41534-025-01051-8

Meng-Jia Chu, Jun Ren, Z. D. Wang

引用次数: 0

Reply to “Comment to ‘The laws of physics do not prohibit counterfactual communication’ ” 回复“对‘物理定律不禁止反事实的交流’的评论”

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-06-10 DOI: 10.1038/s41534-025-01043-8

Hatim Salih, Jonte R. Hance, Will McCutcheon, John Rarity

{"title":"Reply to “Comment to ‘The laws of physics do not prohibit counterfactual communication’ ”","authors":"Hatim Salih, Jonte R. Hance, Will McCutcheon, John Rarity","doi":"10.1038/s41534-025-01043-8","DOIUrl":"https://doi.org/10.1038/s41534-025-01043-8","url":null,"abstract":"In his Comment on our recent paper “The laws of physics do not prohibit counterfactual communication”, npj Quantum Information (2022) 8:60, Popescu argues that the claims of the paper are invalid. Here, we refute his argument, showing that it is based on ignoring the specifics of what we set out to prove (that counterfactual communication is possible for post-selected particles, and more specifically in these cases is not prohibited by the weak trace or consistent histories criteria for particle path), followed by an unwarranted simplification of the protocol. Moreover, the Comment’s excursion into interpretation is misplaced. Our communication protocol is a precisely defined one that allows two remote parties, albeit rarely, to communicate an arbitrarily long binary message, with arbitrarily high accuracy. This is not a matter of interpretation—as the concrete example given in our paper in question illustrates. As for our overarching claim that no particles are exchanged in the course of this communication, we have already demonstrated this both theoretically and experimentally, in the postselected case we consider, as per the weak trace and consistent histories criteria for path of a quantum particle.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"47 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144260535","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