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quantum fisher information of Entangled Coherent States in a Lossy Mach–Zehnder Interferometer

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Communications in Theoretical Physics 2014年第1期61卷 115-120页

作者：井晓幸刘京钟伟王晓光 Zhejiang Institute of Modern Physics Department of PhysicsZhejiang University

We give an analytical result for the quantum fisher information of entangled coherent states in a lossy Mach–Zehnder interferometer recently proposed by Joo et al.,[Phys.Rev.Lett.107(2011)083601].For small loss of photons,we find that the entangled coherent state can surpass the Heisenberg limit.Furthermore,the formalism developed here is applicable to the study of phase sensitivity of multipartite entangled coherent states.

关键词： quantum fisher information entangled coherent state Mach–Zehnder interferometer photon loss

quantum fisher information of a qubit-qutrit system in Garfinkle–Horowitz–Strominger dilation space–time

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Communications in Theoretical Physics 2021年第8期73卷 82-89页

作者： Yi-Jun Lian Jin-Ming Liu State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200241China

We investigate the quantum fisher information(QFI) of a qubit-qutrit system in the background of Garfinkle–Horowitz–Strominger dilation black hole. After deriving the analytical expression of the QFI, we examine its dynamics with respect to the dilation parameter D and the state parameter γ of the system. Our results show that the QFI for the estimation of γ is a fixed value,which is independent of the parameters D and γ. And the QFI for the estimation of D varies with the parameters D and γ. Additionally, we propose an effective strategy to steer the QFI by introducing weak measurement reversal. We find that the QFI can be remarkably enhanced by adjusting the appropriate reversing measurement strengths. Our findings might provide some useful insights for the study on parameter estimation of hybrid systems in the framework of relativity theory.

关键词： quantum fisher information Garfinkle-Horowitz-Strominger space-time weak measurement reversal

Modulating quantum fisher information of qubit in dissipative cavity by coupling strength

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Chinese Physics B 2018年第11期27卷 390-396页

作者：林丹萍刘禹邹红梅 Synergetic Innovation Center for quantum Effects and Application Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education School of Physics and Electronics Hunan Normal University

By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum fisher information（QFI） of an atom qubit system in a dissipation cavity. We obtain the formulae of QFI for two different initial states and analyze the effect of the atom–cavity coupling and the cavity–reservoir coupling on the QFI.The results show that the dynamic behavior of the QFI is obviously dependent on the initial atomic states, the atom–cavity coupling, and the cavity–reservoir coupling. The stronger the atom–cavity coupling, the quicker the QFI oscillates, and the slower the QFI decreases. In particular, the QFI will tend to be a stable value rather than zero if the atom–cavity coupling is large enough. On the other hand, the smaller the cavity–reservoir coupling, the stronger the non-Markovian effect, and the slower the QFI decays. In other words, choosing the best parameter can improve the accuracy of the parameter estimation.In addition, the physical explanation of the dynamic behavior of the QFI is given by means of the QFI flow.

关键词： quantum fisher information parameter estimation dissipative cavity

Chaos and quantum fisher information in the quantum kicked top

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Chinese Physics B 2011年第5期20卷 199-203页

作者：王晓茜马健张喜和王晓光 Department of Physics Changchun University of Science and Technology Zhejiang Institute of Modern Physics Department of PhysicsZhejiang University

quantum fisher information is related to the problem of parameter estimation. Recently, a criterion has been proposed for entanglement in multipartite systems based on quantum fisher information. This paper studies the behaviours of quantum fisher information in the quantum kicked top model, whose classical correspondence can be chaotic. It finds that, first, detected by quantum fisher information, the quantum kicked top is entangled whether the system is in chaotic or in regular case. Secondly, the quantum fisher information is larger in chaotic case than that in regular case, which means, the system is more sensitive in the chaotic case.

关键词： quantum information quantum kicked top quantum fisher information quantum chaos

Dynamics of quantum fisher information in a two-level system coupled to multiple bosonic reservoirs

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Chinese Physics B 2015年第11期24卷 255-259页

作者：王国友郭有能曾可 College of Science Hunan University of Technology Key Laboratory of Low-dimensional quantum Structures and quantum Control of Ministry of Education and Department of PhysicsHunan Normal University Department of Electronic and Communication Engineering Changsha University

We consider the optimal parameter estimation for a two-level system coupled to multiple bosonic reservoirs. By using quantum fisher information （QFI）, we investigate the effect of the Markovian reservoirs＇ number N on QFI in both weak and strong coupling regimes for a two-level system surrounded by N zero-temperature reservoirs of field modes initially in the vacua. The results show that the dynamics of QFI non-monotonically decays to zero with revival oscillations at some time in the weak coupling regime depending on the reservoirs＇ parameters. Furthermore, we also present the relations between the QFI flow, the flows of energy and information, and the sign of the decay rate to gain insight into the physical processes characterizing the dynamics.

关键词： quantum fisher information parameter estimation decay rate

Holevo bound independent of weight matrices for estimating two parameters of a qubit

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Chinese Physics B 2024年第2期33卷 137-143页

作者：牛畅郁司夏 Department of Modern Physics&Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Holevo bound plays an important role in quantum metrology as it sets the ultimate limit for multi-parameter estimations,which can be asymptotically achieved.Except for some trivial cases,the Holevo bound is implicitly defined and formulated with the help of weight matrices.Here we report the first instance of an intrinsic Holevo bound,namely,without any reference to weight matrices,in a nontrivial case.Specifically,we prove that the Holevo bound for estimating two parameters of a qubit is equivalent to the joint constraint imposed by two quantum Cramér–Rao bounds corresponding to symmetric and right logarithmic derivatives.This weightless form of Holevo bound enables us to determine the precise range of independent entries of the mean-square error matrix,i.e.,two variances and one covariance that quantify the precisions of the estimation,as illustrated by different estimation models.Our result sheds some new light on the relations between the Holevo bound and quantum Cramer–Rao bounds.Possible generalizations are discussed.

关键词： quantum metrology quantum fisher information Holevo bound quantum multi-parameter estimation

Parameter estimation in n-dimensional massless scalar field

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Chinese Physics B 2024年第3期33卷 231-237页

作者：杨颖荆继良 Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Educationand Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081Chin

quantum fisher information(QFI)associated with local metrology has been used to parameter estimation in open quantum systems.In this work,we calculated the QFI for a moving Unruh-DeWitt detector coupled with massless scalar fields in n-dimensional spacetime,and analyzed the behavior of QFI with various parameters,such as the dimension of spacetime,evolution time,and Unruh temperature.We discovered that the QFI of state parameter decreases monotonically from 1 to 0 over time.Additionally,we noted that the QFI for small evolution times is several orders of magnitude higher than the QFI for long evolution times.We also found that the value of QFI decreases at first and then stabilizes as the Unruh temperature increases.It was observed that the QFI depends on initial state parameterθ,and Fθis the maximum forθ=0 orθ=π,Fφis the maximum forθ=π/2.We also obtain that the maximum value of QFI for state parameters varies for different spacetime dimensions with the same evolution time.

关键词： quantum fisher information parameter estimation open quantum systems

Distribution of quantum fisher information in spin channel

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Distribution of quantum Fisher information in spin channel

Multi-channel quantum parameter estimation

第三十九届中国控制会议

作者： Hongting Song Qian Xuesen Laboratory of Space Technology China Academy of Space Technology

Towards the statistical distinguishability about parameters encoded in the bipartite quantum state, we mainly investigate the distribution and transformation of quantum fisher information over composite systems in spin channel. The relationship between the global quantum fisher information and the sum of the locally accessible quantum fisher information are studied,which can be subadditivity, additivity, or superadditivity. The transfer among them under the unitary operation is illustrated. We find that the quantum fisher information can not only flow between the reduced systems, but also between the different types of distribution.

关键词： quantum fisher information Spin channel

来源： cnki会议评论

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Science China(information Sciences) 2022年第10期65卷 53-65页

作者： Liying BAO Bo QI Yabo WANG Daoyi DONG Rebing WU Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences University of Chinese Academy of Sciences School of Engineering and information Technology University of New South Wales Department of Automation Tsinghua University

The aim of quantum metrology is to exploit quantum effects to improve the precision of parameter estimation beyond its classical limit. In this paper, we investigate the quantum parameter estimation problem with multiple channels. It is related but not limited to the following two important and practical quantum metrology problems:(i) quantum enhanced metrology with control, whose aim is to improve the precision of quantum sensing by utilizing feedback or open-loop control;(ii) Practical quantum metrology where the underlying evolution of quantum probes may change from a unitary dynamics to an open system dynamics,owing to the inevitable decoherence during the quantum sensing operation. For various kinds of quantum multiple channels, the corresponding quantum channel fisher information is derived. To demonstrate the results, some illustrative examples are given.

关键词： quantum metrology quantum parameter estimation multi-channel quantum fisher information