Protecting Quantum Coherence and Quantum Fisher Information in Ohmic Reservoir
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Protecting Quantum Coherence and Quantum Fisher Information in Ohmic Reservoir Xiao-Zhi Liu1 · Dan Long2 · Hong-Mei Zou2
· Rongfang Liu2 · Jianhe Yang2
Received: 8 June 2020 / Accepted: 29 September 2020 / © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Quantum coherence(QC) and quantum Fisher information(QFI) are investigated for the atom in Jaynes-Cummings model coupling with the Ohmic reservoir at zero temperature when the total excitation number N = 1. We discuss in detail the influence of the atomcavity coupling and the reservoir parameters on QC and QFI. The results show that QC and QFI of the atom can be effectively controlled by the atom-cavity coupling and the reservoir parameters. Namely, the larger atom-cavity coupling and the appropriate reservoir parameters can effectively protect QC and QFI. Moreover, QC can improve QFI. Last, we provide a physical explanation using the decoherence rate. Keywords Quantum coherence · Quantum fisher information · Ohmic reservoir
1 Introduction Quantum coherence(QC) is a fundamental aspect of quantum physics, which describes the capability of a quantum state to exhibit quantum interference phenomena. It constitutes powerful resources for quantum metrology [1, 2] and entanglement creation [3, 4], and is widely used in quantum optics [5–8], quantum information [9]. Recently, various topics of quantum coherence have been drawing a great deal of attention due to the development of quantum information science, such as the relations between quantum coherence and quantum correlations [10, 11], the freezing phenomenon of coherence [12, 13], and the coherent exciton dynamics [14], the optimal distillation of quantum coherence [15] and the l1 -norm coherence of assistance [16].
Xiao-Zhi Liu and Dan Long contributed equally to this article. Hong-Mei Zou
[email protected]; [email protected] 1
School of Electronic Information and Electrical Engineering, Changsha University, Changsha, 410003, People’s Republic of China
2
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, Changsha, 410081, People’s Republic of China
International Journal of Theoretical Physics
Quantum Fisher information(QFI) is one of the most important quantities in quantum estimation theory and quantum information theory, which effectively characterizes the statistical distinguishability about parameters encoded in quantum states and gives the ultimate precision bound on the estimation of parameters, called the Cram´er-Rao inequality [17–20]. QFI has been investigated and applied in quantum metrology, such as the quantum detectors [21, 22], the optimal estimation of phases [23–25], magnetic fields [26, 27], squeezing parameters [28, 29], temperature [30–32], space-time parameters [33, 34]. For an open quantum system, QC and QFI are inevitably destroyed by the surrounding environment. At present, th
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