npj Quantum Information最新文献_第5页

A simple and efficient joint measurement strategy for estimating fermionic observables and Hamiltonians 估计费米子可观测量和哈密顿量的一种简单有效的联合测量策略

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-07 DOI: 10.1038/s41534-025-00957-7

Joanna Majsak, Daniel McNulty, Michał Oszmaniec

{"title":"A simple and efficient joint measurement strategy for estimating fermionic observables and Hamiltonians","authors":"Joanna Majsak, Daniel McNulty, Michał Oszmaniec","doi":"10.1038/s41534-025-00957-7","DOIUrl":"https://doi.org/10.1038/s41534-025-00957-7","url":null,"abstract":"We propose a simple scheme to estimate fermionic observables and Hamiltonians relevant in quantum chemistry and correlated fermionic systems. Our approach is based on implementing a measurement that jointly measures noisy versions of any product of two or four Majorana operators in an N mode fermionic system. To realize our measurement we use: (i) a randomization over a set of unitaries that realize products of Majorana fermion operators; (ii) a unitary, sampled at random from a constant-size set of suitably chosen fermionic Gaussian unitaries; (iii) a measurement of fermionic occupation numbers; (iv) suitable post-processing. Our scheme can estimate expectation values of all quadratic and quartic Majorana monomials to ϵ precision using ({mathcal{O}}(Nlog (N)/{epsilon }^{2})) and ({mathcal{O}}({N}^{2}log (N)/{epsilon }^{2})) measurement rounds respectively, matching the performance offered by fermionic classical shadows1,2. In certain settings, such as a rectangular lattice of qubits which encode an N mode fermionic system via the Jordan-Wigner transformation, our scheme can be implemented in circuit depth ({mathcal{O}}({N}^{1/2})) with ({mathcal{O}}({N}^{3/2})) two-qubit gates, offering an improvement over fermionic and matchgate classical shadows that require depth ({mathcal{O}}(N)) and ({mathcal{O}}({N}^{2})) two-qubit gates. By benchmarking our method on exemplary molecular Hamiltonians and observing performances comparable to fermionic classical shadows, we demonstrate a novel, competitive alternative to existing strategies.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"31 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143789694","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

Frequency-bin entanglement-based Quantum Key Distribution 基于频率仓纠缠的量子密钥分配

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-06 DOI: 10.1038/s41534-025-00991-5

Noemi Tagliavacche, Massimo Borghi, Giulia Guarda, Domenico Ribezzo, Marco Liscidini, Davide Bacco, Matteo Galli, Daniele Bajoni

{"title":"Frequency-bin entanglement-based Quantum Key Distribution","authors":"Noemi Tagliavacche, Massimo Borghi, Giulia Guarda, Domenico Ribezzo, Marco Liscidini, Davide Bacco, Matteo Galli, Daniele Bajoni","doi":"10.1038/s41534-025-00991-5","DOIUrl":"https://doi.org/10.1038/s41534-025-00991-5","url":null,"abstract":"Entanglement is an essential ingredient in many quantum communication protocols. In particular, entanglement can be exploited in quantum key distribution (QKD) to generate two correlated random bit strings whose randomness is guaranteed by the nonlocal property of quantum mechanics. Most of QKD protocols tested to date rely on polarization and/or time-bin encoding. Despite compatibility with existing fiber-optic infrastructure and ease of manipulation with standard components, frequency-bin QKD have not yet been fully explored. Here we report a demonstration of entanglement-based QKD using frequency-bin encoding. We implement the BBM92 protocol using photon pairs generated by two independent, high-finesse, ring resonators on a silicon photonic chip. We perform a passive basis selection scheme and simultaneously record sixteen projective measurements. A key finding is that frequency-bin encoding is sensitive to the random phase noise induced by thermal fluctuations of the environment. To correct for this effect, we developed a real-time adaptive phase rotation of the measurement basis, achieving stable transmission over a 26 km fiber spool with a secure key rate ≥ 4.5 bit/s. Our work introduces a new degree of freedom for the realization of entangled based QKD protocols in telecom networks.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"73 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784810","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 sensing with duplex qubits of silicon vacancy centers in SiC at room temperature 室温下SiC中硅空位中心双量子位的量子传感

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-05 DOI: 10.1038/s41534-025-01011-2

Kosuke Tahara, Shin-ichi Tamura, Haruko Toyama, Jotaro J. Nakane, Katsuhiro Kutsuki, Yuichi Yamazaki, Takeshi Ohshima

{"title":"Quantum sensing with duplex qubits of silicon vacancy centers in SiC at room temperature","authors":"Kosuke Tahara, Shin-ichi Tamura, Haruko Toyama, Jotaro J. Nakane, Katsuhiro Kutsuki, Yuichi Yamazaki, Takeshi Ohshima","doi":"10.1038/s41534-025-01011-2","DOIUrl":"https://doi.org/10.1038/s41534-025-01011-2","url":null,"abstract":"The silicon vacancy center in Silicon Carbide (SiC) provides an optically addressable qubit at room temperature in its spin-(frac{3}{2}) electronic state. However, optical spin initialization and readout are less efficient compared to those of spin-1 systems, such as nitrogen-vacancy centers in diamond, under non-resonant optical excitation. Spin-dependent fluorescence exhibits contrast only between (| m=pm 3/2left.rightrangle) and (| m=pm 1/2left.rightrangle) states, and optical pumping does not create a population difference between (| +1/2left.rightrangle) and (| -1/2left.rightrangle) states. Thus, operating one qubit (e.g., (left{| +3/2left.rightrangle ,| +1/2left.rightrangle right}) states) leaves the population in the remaining state ((| -1/2left.rightrangle)) unaffected, contributing to background in optical readout. To mitigate this problem, we propose a sensing scheme based on duplex qubit operation in the quartet, using microwave pulses with two resonant frequencies to simultaneously operate (left{| +3/2left.rightrangle ,| +1/2left.rightrangle right}) and (left{| -1/2left.rightrangle ,| -3/2left.rightrangle right}). Experimental results demonstrate that this approach doubles signal contrast in optical readout and improves sensitivity in AC magnetometry compared to simplex operation.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"16 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782626","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

Industrial 300 mm wafer processed spin qubits in natural silicon/silicon-germanium 工业300毫米晶圆用天然硅/硅锗加工自旋量子位

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-05 DOI: 10.1038/s41534-025-01016-x

Thomas Koch, Clement Godfrin, Viktor Adam, Julian Ferrero, Daniel Schroller, Noah Glaeser, Stefan Kubicek, Ruoyu Li, Roger Loo, Shana Massar, George Simion, Danny Wan, Kristiaan De Greve, Wolfgang Wernsdorfer

{"title":"Industrial 300 mm wafer processed spin qubits in natural silicon/silicon-germanium","authors":"Thomas Koch, Clement Godfrin, Viktor Adam, Julian Ferrero, Daniel Schroller, Noah Glaeser, Stefan Kubicek, Ruoyu Li, Roger Loo, Shana Massar, George Simion, Danny Wan, Kristiaan De Greve, Wolfgang Wernsdorfer","doi":"10.1038/s41534-025-01016-x","DOIUrl":"https://doi.org/10.1038/s41534-025-01016-x","url":null,"abstract":"The realisation of a universal quantum computer will require the operation of many thousands to millions of coherently coupled qubits. The possibility of using existing industrial semiconductor fabrication techniques and infrastructure for up-scaling and reproducibility makes silicon based spin qubits one of the most promising platforms to achieve this goal. The implementation of the up to now largest semiconductor based quantum processor was realised in a silicon/silicon-germanium heterostructure known for its low charge noise, long qubit coherence times and fast driving speeds, but the high structural complexity creates challenges for industrial implementations. Here we demonstrate quantum dots hosted in a natural Si/SiGe heterostructure fully fabricated by an industrial 300 mm semiconductor wafer process line from heterostructure growth to Co micromagnet monolithic integration. We report charge noise values below 2 μeV/(sqrt{{rm{Hz}}}), spin relaxation times exceeding 1 s, and coherence times ({T}_{2}^{* }) and ({T}_{2}^{H}) of 1 μs and 50 μs respectively, for quantum wells grown using natural silicon. Further, we achieve Rabi frequencies up to 5 MHz and single qubit gate fidelities above 99%. In addition to scalability, the high reproducibility of the 300 mm processes enables the deterministic study of qubit metric dependencies on process parameters, which is essential for optimising qubit quality.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"70 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782629","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-enhanced imaging for characterizing anisotropic material 表征各向异性材料的量子增强成像

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-04 DOI: 10.1038/s41534-025-01014-z

Meng-Yu Xie, Su-Jian Niu, Zhao-Qi-Zhi Han, Yin-Hai Li, Ren-Hui Chen, Xiao-Hua Wang, Ming-Yuan Gao, Li Chen, Yue-Wei Song, Zhi-Yuan Zhou, Bao-Sen Shi

{"title":"Quantum-enhanced imaging for characterizing anisotropic material","authors":"Meng-Yu Xie, Su-Jian Niu, Zhao-Qi-Zhi Han, Yin-Hai Li, Ren-Hui Chen, Xiao-Hua Wang, Ming-Yuan Gao, Li Chen, Yue-Wei Song, Zhi-Yuan Zhou, Bao-Sen Shi","doi":"10.1038/s41534-025-01014-z","DOIUrl":"https://doi.org/10.1038/s41534-025-01014-z","url":null,"abstract":"Polarimetric imaging, a technique that captures the invisible polarization-related properties of given materials, has broad applications from fundamental physics to advanced fields such as target recognition, stress detection, biomedical diagnosis and remote sensing. The introduction of quantum sources into classical imaging systems has demonstrated distinct advantages, yet few studies have explored their combination with polarimetric imaging. In this study, we present a quantum polarimetric imaging system that integrates polarization-entangled photon pairs into a polarizer-sample-compensator-analyzer-typed polarimeter. Our system visualizes the birefringence properties of a periodical-distributed anisotropic material under decreasing illumination levels and diverse disturbing light sources. Compared to the classical system, the quantum approach reveals the superior sensitivity and robustness in low-light conditions, particularly useful in biomedical studies where the low illumination and non-destructive detection are urgently needed. The study also highlights the nonlocality of entangled photons in birefringence measurement, indicating the potential of quantum polarimetric system in the remote sensing domain.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"37 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143775659","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

Unified framework for calculating convex roof resource measures 凸顶板资源测度计算的统一框架

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-04 DOI: 10.1038/s41534-025-01012-1

Xuanran Zhu, Chao Zhang, Zheng An, Bei Zeng

{"title":"Unified framework for calculating convex roof resource measures","authors":"Xuanran Zhu, Chao Zhang, Zheng An, Bei Zeng","doi":"10.1038/s41534-025-01012-1","DOIUrl":"https://doi.org/10.1038/s41534-025-01012-1","url":null,"abstract":"Quantum resource theories (QRTs) provide a comprehensive and practical framework for the analysis of diverse quantum phenomena. A fundamental task within QRTs is the quantification of resources inherent in a given quantum state. In this work, we introduce a unified computational framework for a class of widely utilized quantum resource measures, derived from convex roof extensions. We establish that the computation of these convex roof resource measures can be reformulated as an optimization problem over a Stiefel manifold, which can be further unconstrained through polar projection. Compared to existing methods employing semi-definite programming (SDP), gradient-based techniques or seesaw strategy, our approach not only demonstrates satisfying computational efficiency but also maintains applicability across various scenarios within a unified framework. We substantiate the efficacy of our method by applying it to several key quantum resources, including entanglement, coherence, and magic states. Moreover, our methodology can be readily extended to other convex roof quantities beyond the domain of resource theories, suggesting broad applicability in the realm of quantum information theory.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"79 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143775660","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 simulations of chemistry in first quantization with any basis set 具有任意基集的第一量子化化学量子模拟

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-04-01 DOI: 10.1038/s41534-025-00987-1

Timothy N. Georges, Marius Bothe, Christoph Sünderhauf, Bjorn K. Berntson, Róbert Izsák, Aleksei V. Ivanov

{"title":"Quantum simulations of chemistry in first quantization with any basis set","authors":"Timothy N. Georges, Marius Bothe, Christoph Sünderhauf, Bjorn K. Berntson, Róbert Izsák, Aleksei V. Ivanov","doi":"10.1038/s41534-025-00987-1","DOIUrl":"https://doi.org/10.1038/s41534-025-00987-1","url":null,"abstract":"Quantum computation of the energy of molecules and materials is one of the most promising applications of fault-tolerant quantum computers. Practical applications require development of quantum algorithms with reduced resource requirements. Previous work has mainly focused on quantum algorithms where the Hamiltonian is represented in second quantization with compact basis sets while existing methods in first quantization are limited to a grid-based basis. In this work, we present a new method to solve the generic ground-state chemistry problem in first quantization using any basis set. We achieve asymptotic speedup in Toffoli count for molecular orbitals, and orders of magnitude improvement using dual plane waves as compared to the second quantization counterparts. In some instances, our approach provides similar or even lower resources compared to previous first quantization plane wave algorithms that, unlike our approach, avoids the loading of the classical data. The developed methodology can be applied to variety of applications, where the matrix elements of a first quantized Hamiltonian lack simple circuit representation.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"42 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745684","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 causal inference with extremely light touch 极轻触摸的量子因果推理

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-03-29 DOI: 10.1038/s41534-024-00956-0

Xiangjing Liu, Yixian Qiu, Oscar Dahlsten, Vlatko Vedral

引用次数: 0

Free-space continuous-variable quantum key distribution under high background noise 高背景噪声下自由空间连续变量量子密钥分布

IF 7.6 1区物理与天体物理

npj Quantum Information Pub Date : 2025-03-27 DOI: 10.1038/s41534-025-01009-w

Xue-Tao Zheng, Qi-Fa Zhang, Jie Ling, Guang-Can Guo, Zheng-Fu Han

引用次数: 0

Networking quantum networks with minimum cost aggregation 用最低成本聚合技术实现量子网络联网