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quantum coherence and non-Markovianity of an atom in a dissipative cavity under weak measurement

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Chinese Physics B 2018年第1期27卷 258-262页

作者：刘禹邹红梅方卯发 Key Laboratory of Low-dimensional quantum Structures and quantum Control of Ministry of Education College of Physics and Information Science Hunan Normal University

quantum coherence and non-Markovianity of an atom in a dissipative cavity under weak measurement are investigated in this work. We find that： the quantum coherence obviously depends on the initial atomic state, the strength of the weak measurement and its reversal, the atom-cavity coupling constant and the non-Markovian effect. It is obvious that the weak measurement effect protects the coherence better. The quantum coherence is preserved more efficiently for larger atom- cavity coupling. The stronger the non-Markovian effect is, the more slowly the coherence reduces. The quantum coherence can be effectively protected by means of controlling these physical parameters.

关键词： quantum coherence non-Markovianty dissipative cavity

Detecting coherence with respect to general quantum measurements

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Science China(Information Sciences) 2023年第8期66卷 52-60页

作者： Yu-Cheng CHEN Jiong CHENG Wen-Zhao ZHANG Cheng-Jie ZHANG School of Physical Science and Technology Ningbo University State Key Laboratory of Precision Spectroscopy School of Physics and Electronic Science East China Normal University

quantum coherence is crucial in quantum resource theory. Previous studies have mainly focused on standard coherence based on a complete orthogonal reference. Standard coherence has recently been extended to general positive-operator-valued measure(POVM)-based coherence, including block coherence as a special case. Therefore, it is necessary to construct block and POVM-based coherence witnesses to detect them. In this study, we present witnesses for block and POVM-based coherence and obtain the necessary and sufficient conditions for constructing these witnesses. We also discuss possible realizations of some block and POVM-based coherence witnesses in experiments and present examples of measuring block coherence witnesses based on real experimental data. Furthermore, we present an application of block coherence witnesses in a quantum-parameter estimation task with a degenerate Hamiltonian and estimate the unknown parameter by measuring the block coherence witnesses when the input state is block coherent.Finally, we prove that the quantum Fisher information of any block-incoherent state equals zero, which coincides with the result obtained from measuring block coherence witnesses.

关键词： coherence witness general quantum measurements block coherence POVM-based coherence quantum coherence

quantum coherence Quantifiers Based on Rényi α-Relative Entropy

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Communications in Theoretical Physics 2017年第6期67卷 631-636页

作者：邵连合李永明罗宇席政军 College of Computer Science Shaanxi Normal University

The resource theories of quantum coherence attract a lot of attention in recent years. Especially, the monotonicity property plays a crucial role here. In this paper we investigate the monotonicity property for the coherence measures induced by the Rényi α-relative entropy, which present in [Phys. Rev. A 94(2016) 052336]. We show that the Rényi α-relative entropy of coherence does not in general satisfy the monotonicity requirement under the subselection of measurements condition and it also does not satisfy the extension of monotonicity requirement, which presents in [Phys.Rev. A 93(2016) 032136]. Due to the Rényi α-relative entropy of coherence can act as a coherence monotone quantifier,we examine the trade-off relations between coherence and mixedness. Finally, some properties for the single qubit of Rényi 2-relative entropy of coherence are derived.

关键词： quantum coherence Rényi α-relative entropy monotonicity mixedness

quantum coherence and ground-state phase transition in a four-chain Bose–Hubbard model

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Communications in Theoretical Physics 2021年第8期73卷 182-188页

作者： Ji-Guo Wang Lin-Qi Guo Ya-Fei Song Department of Mathematics and Physics Shijiazhuang TieDao UniversityShijiazhuang 050043China Institute of Applied Physics Shijiazhuang TieDao UniversityShijiazhuang 050043China

We study the quantum coherence and ground-state phase transition of a four-chain Bose–Hubbard model with the long-range interaction. In a special four-chain Bose–Hubbard model,i.e., each chain only has one optical potential, four types of the ground-state phases are discovered. The effects of the disorder, the on-site interaction and the long-range interaction on the quantum coherence are studied. For the system without the long-range interaction, the quantum coherence changes from one periodic oscillation to two periodic oscillations as the onsite interaction increases. By considering the long-range interaction, the quantum coherence goes back to one periodic oscillation again. The on-site interaction itself suppresses the quantum coherence, both the on-site interaction and long-range interaction together enhance the quantum coherence with the weak disorder. If the disorder strength is increased beyond a critical value,they start to suppress the quantum coherence. In a regular four-chain Bose–Hubbard model, i.e.,each chain has many optical potentials, the ground-state phase transitions are obtained by using the cluster Gutzwiller mean-field method. Exotic ground-state phases are found, i.e., superfluid phase, integer Mott insulator phase, supersolid phase and loophole insulator phase. The combination of the loophole insulator phase and the supersolid phase expands the lobes with the half-integer filling per site for the small ratio β = t_(‖)/t_(⊥).

关键词： Bose-Hubbard model quantum coherence ground-state phase transition

quantum synchronization with correlated baths

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Chinese Physics B 2024年第2期33卷 152-157页

作者：李磊王春辉尹洪浩王如泉刘伍明 School of Physical Science and Technology Inner Mongolia UniversityHohhot 010021China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

We study quantum synchronization under the nonequilibrium reservoirs.We consider a two-qubit XXZ chain coupled independently to their own reservoirs modeled by the collisional model.Two reservoir particles,initially prepared in a thermal state or a state with coherence,are correlated through a unitary transformation and afterward interact locally with the two quantum subsystems.We study the quantum effect of reservoir on synchronous dynamics of system.By preparing different reservoir initial states or manipulating the reservoir particles coupling and the temperature gradient,we find that quantum entanglement of reservoir is the key to control quantum synchronization of system qubits.

关键词： quantum synchronization entanglement quantum coherence nonequilibrium reservoir

Spatial quantum coherent modulation with perfect hybrid vector vortex beam based on atomic medium

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Chinese Physics B 2024年第2期33卷 360-364页

作者：马燕杨欣常虹杨鑫琪曹明涛张晓斐高宏董瑞芳张首刚 Key Laboratory of Time Reference and Applications National Time Service CenterChinese Academy of SciencesXi’an 710600China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Shaanxi Key Laboratory of Quantum Information and Quantum Optoelectronic DevicesSchool of ScienceXi’an Jiaotong UniversityXi’an 710049China Department of Physics Shaanxi University of Science and TechnologyXi’an 710021China Hefei National Laboratory Hefei 230088China

The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we investigate the spatial quantum coherent modulation effect with PHVVB based on the atomic medium,and we observe the absorption characteristic of the PHVVB with different TCs under variant magnetic fields.We find that the transmission spectrum linewidth of PHVVB can be effectively maintained regardless of the TC.Still,the width of transmission peaks increases slightly as the beam size expands in hot atomic vapor.This distinctive quantum coherence phenomenon,demonstrated by the interaction of an atomic medium with a hybrid vector-structured beam,might be anticipated to open up new opportunities for quantum coherence modulation and accurate magnetic field measurement.

关键词： perfect hybrid vector vortex beam topological charge quantum coherence optical manipulation

Enhancement of charging performance of quantum battery via quantum coherence of bath

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Chinese Physics B 2023年第1期32卷 161-171页

作者：于文莉张允李海魏广芬韩丽萍田峰邹建 School of Computer Science and Technology Shandong Technology and Business UniversityYantai 264005China School of Information and Electronic Engineering Shandong Technology and Business UniversityYantai 264005China School of Science Tianjin University of TechnologyTianjin 300384China School of Physics Beijing Institute of TechnologyBeijing 100081China

An open quantum battery(QB)model of a single qubit system charging in a coherent auxiliary bath(CAB)consisting of a series of independent coherent ancillae is considered.According to the collision charging protocol we derive a quantum master equation and obtain the analytical solution of QB in a steady state.We find that the full charging capacity(or the maximal extractable work(MEW))of QB,in the weak QB-ancilla coupling limit,is positively correlated with the coherence magnitude of ancilla.Combining with the numerical simulations we compare with the charging properties of QB at finite coupling strength,such as the MEW,average charging power and the charging efficiency,when considering the bath to be a thermal auxiliary bath(TAB)and a CAB,respectively.We find that when the QB with CAB,in the weak coupling regime,is in fully charging,both its capacity and charging efficiency can go beyond its classical counterpart,and they increase with the increase of coherence magnitude of ancilla.In addition,the MEW of QB in the regime of relative strong coupling and strong coherent magnitude shows the oscillatory behavior with the charging time increasing,and the first peak value can even be larger than the full charging MEW of QB.This also leads to a much larger average charging power than that of QB with TAB in a short-time charging process.These features suggest that with the help of quantum coherence of CAB it becomes feasible to switch the charging schemes between the long-time slow charging protocol with large capacity and high efficiency and the short-time rapid charging protocol with highly charging power only by adjusting the coupling strength of QB-ancilla.This work clearly demonstrates that the quantum coherence of bath can not only serve as the role of“fuel”of QB to be utilized to improve the QB's charging performance but also provide an alternative way to integrate the different charging protocols into a single QB.

关键词： quantum battery quantum coherence maximal extractable work charging power

quantum coherence~ correlations and dynamics of ultracold atoms： From fundamental research to future technology

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Frontiers of physics 2012年第1期7卷 1-2页

作者： Chaohong Lee (1) Peter D. Drummond (2) Masahito Ueda (3) 1. State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and Engineering Sun Yat-Sen University Guangzhou 510275 China2. Centre for Atom Optics and Ultrafast Spectroscopy Swinburne University of Technology Melbourne 3122 Australia3. Department of Physics University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan

coherence and correlation are at. the heart of all quantum sciences The emerging quan- tum technologies crucially depend on exot, ic coherence and correlations that cannot, be found in classical systems, To realize qu... 详细信息

关键词： quantum coherence correlations future technology

The application of quantum coherence as a resource

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Chinese Physics B 2023年第11期32卷 1-15页

作者：刘思远范桁 Institute of Modern Physics Northwest UniversityXi’an 710127China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi’an 710127China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological quantum Computation University of Chinese Academy of SciencesBeijing 100190China Beijing Academy of quantum Information Sciences Beijing 100193China

quantum coherence is a basic concept in quantum mechanics, representing one of the most fundamental characteristics that distinguishes quantum mechanics from classical physics. quantum coherence is the basis for multi-particle interference and quantum entanglement. It is also the essential ingredient for various physical phenomena in quantum optics, quantum information, etc. In recent years, with the proposal of a quantum coherence measurement scheme based on a resource theory framework, quantum coherence as a quantum resource has been extensively investigated. This article reviews the resource theories of quantum coherence and introduces the important applications of quantum coherence in quantum computing,quantum information, and interdisciplinary fields, particularly in quantum thermodynamics and quantum biology. quantum coherence and its applications are still being explored and developed. We hope this review can provide inspiration for relevant research.

关键词： quantum coherence quantum computing quantum information quantum thermodynamics quan-tum biology