Quantum Fisher information affected by fluctuating vacuum electromagnetic field with a boundary
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THE EUROPEAN PHYSICAL JOURNAL D
Regular Article
Quantum Fisher information affected by fluctuating vacuum electromagnetic field with a boundary Zhiming Huang1 and Zhimin He2,3,a 1 2 3
School of Economics and Management, Wuyi University, Jiangmen 529020, P.R. China School of Electronic and Information Engineering, Foshan University, Foshan 528000, P.R. China Center for Quantum Computing, Peng Cheng Laboratory, Shenzhen 518055, P.R. China Received 11 March 2020 / Received in final form 12 May 2020 Published online 18 June 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. We study the behaviors of quantum Fisher information (QFI) for an accelerated atom interacted with fluctuating electromagnetic vacuum near a perfectly reflecting boundary. The master equation that governs the atom evolution is firstly derived. In the case without boundary, the fluctuation and acceleration of electromagnetic vacuum always attenuate the QFI. Nevertheless, in the presence of a boundary, the degradation, oscillation, and maintaining of QFI are dependent on the atom-boundary distance, acceleration and polarization direction of atom. The boundary can efficiently shield QFI from the impact of the fluctuating electromagnetic vacuum and acceleration in some certain conditions and let us have more freedom of manipulating the precision of parameter estimation.
1 Introduction Quantum Fisher information (QFI) provides the precision bound of the parameter estimation in quantum metrology, which is called quantum Cram´er–Rao inequality [1,2]. QFI plays significant role in quantum estimation theory and quantum information theory, such as optimal estimation of phases [3,4], characterizing non-Markovianity [5], measuring coherence and entanglement [6,7], quantum phase transition [8,9], quantum clone [10,11], and so on. A greater QFI denotes that the parameter can be estimated with a higher precision. Thus, improving QFI is an important problem in parameter quantum estimation in real system. However, in reality, quantum system inevitably interacts with the environment, which may cause the system fluctuation and decoherence, and decrease the estimation precision. Therefore, it is important to investigate the dynamics of QFI in open system [12–16], as we do in discussing quantum entanglement [17,18], quantum correlation [19–21], and quantum coherence [22,23] in open quantum system. No system can be isolated from the environment of quantum fluctuation in quantum sense, which is the appearance of energetic particles in an empty space. On the other hand, a conductor boundary can profoundly modify quantum fluctuation [24–27]. Accelerated object in vacuum can induce Unruh thermal effect [28]. In general, a parameter estimation problem needs three steps [29]: the preparation of a probe system, its interaction with a
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the dynamic system in which the estimated parameters are involved, and the measurement of the modified probe system after the evolution. To expl
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