We identify the multiparameter sensitivity of split nonclassical spin states, such as spin-squeezed and Dicke states spatially distributed into several addressable modes. Analytical expressions for the spin-squeezing matrix of a family of states that are accessible by current atomic experiments reveal the quantum gain in multiparameter metrology, as well as the optimal strategies to maximize the sensitivity. We further study the mode entanglement of these states by deriving a witness for genuine $k$-partite mode entanglement from the spin-squeezing matrix. Our results highlight the advantage of mode entanglement for distributed sensing, and outline optimal protocols for multiparameter estimation with nonclassical spatially-distributed spin ensembles.
Sensitivity Bounds of Multiparameter Metrology at Thermal Equilibrium
College of Electronics and Information Engineering, Tongji University（同济大学电子与信息工程学院）；Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University（同济大学上海智能自主系统研究院）
Quantum multiparameter metrology with generalized entangled coherent state
提出了一种广义纠缠相干态，并将其应用于多臂光干涉仪中，实现了多个相位的估计。我们得到的量子Cramer-Rao界限的线性和非线性参数化协议。通过分析，我们发现，利用同时估计，这种广义形式的ECS比广义NOON态[Phys. Rev. Lett. \textbf{111}，070403（2013）]。此外，与独立估计相比，线性和非线性协议具有相同的优势，在与参数的数量的关系。
Precision Limits of Multiparameter Markovian-Noise Metrology
Joint Center for Quantum Information and Computer Science, NIST/University of Maryland（量子信息与计算联合中心，美国国家标准与技术研究院/马里兰大学）；Joint Quantum Institute, NIST/University of Maryland（量子信息联合研究所，美国国家标准与技术研究院/马里兰大学）；Quantum and Condensed Matter Physics Group (T-4), Theoretical Division, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室理论部量子与凝聚态物理组（T-4））
A geometric criterion for optimal measurements in multiparameter quantum metrology
Zhejiang University（浙江大学）；Nordita, KTH Royal Institute of Technology and Stockholm University（诺迪塔，皇家理工学院和斯德哥尔摩大学）；University of Tsukuba（筑波大学）；Institute of Systems and Information Engineering, University of Tsukuba（筑波大学系统信息工程学院）；Center for Artificial Intelligence Research (C-AIR), University of Tsukuba（筑波大学人工智能研究中心）；Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO)（意大利国家光学研究所）；European Laboratory for Nonlinear Spectroscopy (LENS), University of Florence（欧洲非线性光谱学实验室，佛罗伦萨大学）
Hierarchy of saturation conditions for multiparameter quantum metrology bounds
Institute of Systems and Information Engineering, University of Tsukuba（筑波大学系统信息工程学院）；Center for Artificial Intelligence Research (C-AIR), University of Tsukuba（筑波大学人工智能研究中心）；Institute of Fundamental and Transdisciplinary Research, Institute of Quantum Sensing, and Institute for Advanced Study in Physics, Zhejiang University（浙江大学基础与跨学科研究院、量子传感研究所、物理高等研究院）；Nordita, KTH Royal Institute of Technology and Stockholm University（诺迪塔，皇家理工学院和斯德哥尔摩大学）；Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO)（意大利国家光学研究所（CNR-INO））；European Laboratory for Nonlinear Spectroscopy (LENS)（欧洲非线性光谱学实验室）
Quantum error correction for multiparameter metrology
Key Laboratory of Quantum Physics and Photonic Quantum Information, Ministry of Education, University of Electronic Science and Technology of China（电子科技大学量子与光子量子信息教育部重点实验室）；Shimmer Center, Tianfu Jiangxi Laboratory（天府江西实验室闪烁中心）
Geometric bounds on multiparameter Heisenberg scaling in optical metrology with limited squeezed resources
University of Portsmouth（朴茨茅斯大学）；Quantum Science and Technology Hub, University of Portsmouth（朴茨茅斯大学量子科学与技术中心）；Università di Bari（巴里大学）；INFN, Sezione di Bari（意大利国家核物理研究所巴里分部）；Institute of Cosmology and Gravitation, University of Portsmouth（朴茨茅斯大学宇宙学与引力研究所）
Control incompatibility in multiparameter quantum metrology
Pritzker School of Molecular Engineering, The University of Chicago（芝加哥大学普里茨克分子工程学院）；MIT-Harvard Center for Ultracold Atoms and Research Laboratory of Electronics, Massachusetts Institute of Technology（麻省理工学院哈佛-麻省中心超冷原子与电子学研究室）；Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong（香港中文大学机械与自动化工程系）；Department of Nuclear Science and Engineering, Massachusetts Institute of Technology（麻省理工学院核科学与工程系）；School of Physics, Xi’an Jiaotong University（西安交通大学物理学院）；International Center for Quantum Materials, School of Physics, Peking University（北京大学物理学院量子材料国际中心）
Dynamical, thermal, and ground-state multiparameter quantum metrology: Fundamental limits and their attainability in magnetometry
Universitat Autònoma de Barcelona（巴塞罗那自治大学）；Università di Bologna（博洛尼亚大学）；BITS Pilani KK Birla Goa Campus（比拉印度理工学院果阿校区）；Harish-Chandra Research Institute（哈里什-钱德拉研究所）；Institute for Quantum Optics and Quantum Information - IQOQI Vienna, Austrian Academy of Sciences（奥地利科学院维也纳量子光学与量子信息研究所）
