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Steady and optimal entropy squeezing for three types of moving three-level atoms coupled with a single-mode coherent field

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Chinese Physics B 2021年第1期30卷 164-169页

作者： Wen-Jin Huang Mao-Fa Fang Synergetic Innovation Center for quantum Effects and Applications Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of EducationSchool of Physics and ElectronicsHunan Normal UniversityChangsha 410081China

The entropy squeezing properties of different types of moving three-level atoms coupled with a single-mode coherent field are studied. The influences of the moving velocity and initial states of the three-level atom on the entropy squeezing are discussed. The results show that, the entropy squeezing properties of the three-level atom depend on its initial state, moving velocity, and the type. A stationary three-level atom can not obtain a steady entropy squeezing whatever initial conditions are chosen, while a moving three-level atom can achieve a steady and optimal entropy squeezing through choosing higher velocity and appropriate initial state. Our result provides a simple method for preparing squeezing resources with ultra-low quantum noise of the three-level atomic system without additional any complex techniques.

关键词： entropy squeezing moving three-level atom single-mode coherent field

Entropy squeezing for a V-type three-level atom interacting with a single-mode field and passing through the amplitude damping channel with weak measurement

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Chinese Physics B 2021年第1期30卷 158-163页

作者： Cui-Yu Zhang Mao-Fa Fang Synergetic Innovation Center for quantum Effects and Applications Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of EducationSchool of Physics and ElectronicsHunan Normal UniversityChangsha 410081China

The entropy squeezing of a V-type three-level atom interacting with a single-mode field and passing through the amplitude damping channel is investigated in detail. Our results show that when coupled to the single-mode field, the atom in appropriate initial states can not only generate obvious entropy squeezing but also keep in the optimal squeezing state,while passing through the amplitude damping channel, the atom can generate entropy squeezing under the control of the weak measurement. Besides, it is proved again that as a measurement method for atomic squeezing, the entropy squeezing is precise and effective. Therefore our work is instructive for experiments in preparing three-level system information resource with ultra-low quantum noise.

关键词： entropy squeezing V-type three-level atom single-mode field weak measurement

Reduction of entropy uncertainty for qutrit system under non-Markov noisy environment

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Chinese Physics B 2020年第4期29卷 165-171页

作者： Xiong Xu Mao-Fa Fang Synergetic Innovation Center for quantum Effects and Applications Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of EducationSchool of Physics and ElectronicsHunan Normal UniversityChangsha 410081China

We explore the entropy uncertainty for qutrit system under non-Markov noisy environment and discuss the effects of the quantum memory system and the spontaneously generated interference(SGI)on the entropy uncertainty in *** results show that,the entropy uncertainty can be reduced by using the methods of quantum memory system and adjusting of ***,the entropy uncertainty can be decreased obviously when both the quantum memory system and the SGI are simultaneously applied.

关键词： entropy uncertainty relation non-Markov noisy qutrit and spontaneously generated interference

Generation of sustained optimal entropy squeezing of a two-level atom via non-Hermitian operation

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Chinese Physics B 2018年第11期27卷 506-511页

作者： Yan-Yi Wang Mao-Fa Fang Synergetic Innovation Center for quantum Effects and Application and Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education School of Physics and Electronics Hunan Normal University Changsha 410081 China

We investigate the entropy squeezing of a two-level atom in the Jaynes–Cummings model, and provide a scheme to generate the sustained optimal entropy squeezing of the atom via non-Hermitian operation. Our results show that the squeezing degree and the persistence time of entropy squeezing of atomic polarization components greatly depend on the non-Hermiticity intensity in non-Hermitian operation. Especially, under a proper choice of non-Hermiticity parameters, the sustained optimal entropy squeezing of the atom can be generated even though the atom is initially prepared in a no entropy squeezing state.

关键词： entropy squeezing non-Hermitian dynamics quantum optics Jaynes-Cummings model

Entropy squeezing for three-level atom interacting with a single-mode field

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Chinese Physics B 2019年第6期28卷 81-86页

作者： Fei-Fan Liu Mao-Fa Fang Xiong Xu Synergetic Innovation Center for quantum Effects and Application Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of EducationSchool of Physics and ElectronicsHunan Normal UniversityChangsha 410081China

The entropy squeezing for a three-level atom interacting with a single-model field is studied. A general definition of entropy squeezing for three-level atom is given according to entropic uncertainty relation of three-level system, and the calculation formalism of entropy is derived for a cascade three-level atom. By using numerical calculation, the entropy squeezing properties of a cascade three-level atom are examined. Our results show that, three-level atom can generate obvious entropy squeezing effect via choosing appropriate superposition state of three-level atom. Our results are meaningful for preparing three-level system information resources with ultra-low quantum noise.

关键词： variance squeezing entropy squeezing three-level atom

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： Danping Lin Yu Liu Hong-Mei Zou 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 China

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 *** 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 *** 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

quantum thermal discord in a two-spin-1/2 XXZ model

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Chinese Physics B 2010年第10期19卷 100-104页

作者：王琼廖洁桥曾浩生 key laboratory of low-dimensional quantum structures and quantum control of ministry of education and Department of Physics Hunan Normal University Institute of Theoretical Physics Chinese Academy of Sciences

We study the quantum discord in a two-spin-1/2 XXZ model in thermal equilibrium at temperature T in the presence of an external magnetic field B. Special attention is paid to the dependence of quantum discord on the temperature T and magnetic field B. It is found that quantum thermal discord is more robust than concurrence against temperature, in the sense that quantum thermal discord does not vanish at finite temperatures, but concurrence vanishes completely at a critical temperature.

关键词： quantum discord concurrence thermal equilibrium

Preparation of entangled states of atomic qubits via atom-cavity-laser interaction

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Chinese Optics Letters 2010年第5期8卷 529-532页

作者：郭裕刘桂云 Department of Physics and Electronic Science Changsha University of Science and Technology key laboratory of low-dimensional quantum structures and quantum control(Hunan Normal University) Ministry of Education

We propose a scheme to prepare the Bell states for atomic qubits trapped in separate optical cavities via atom-cavity-laser *** quantum information of each qubit is encoded on the degenerate ground states of the atom,so the entanglement between them is relatively stable against spontaneous *** proposed scheme consists of a Mach-Zehnder interferometer（MZI） with two arms,and each arm contains a cavity with an N-type atom in *** requires two classical fields and a single-photon source. By controlling the sequence and time of atom-cavity-laser interaction,the deterministic production of the atomic Bell states is *** also introduce the generalization of the present scheme to generate the 2N-atom Greenberger-Horne-Zeilinger state.

关键词： Bells Laser tissue interaction Plasma interactions quantum entanglement quantum optics

controllable cross-Kerr interaction between microwave photons in circuit quantum electrodynamics

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Chinese Physics B 2011年第3期20卷 227-232页

作者：吴琴琴廖洁桥匡乐满 laboratory of low-dimensional quantum structures and quantum control of ministry of education and Department of PhysicsHunan Normal University Department of Physics Hunan Institute of Science and Technology

We propose a scheme to enable a controllable cross-Kerr interaction between microwave photons in a circuit quantum electrodynamics （QED） system. In this scheme we use two transmission-line resonators （TLRs） and one superconducting quantum interference device （SQUID） type charge qubit, which acts as an artificial atom. It is shown that in the dispersive regime of the eircuit-QED system, a controllable cross-Kerr interaction can be obtained by properly preparing the initial state of the qubit, and a large cross-phase shift between two microwave fields in the two TLRs can then be reached. Based on this cross-Kerr interaction, we show how to create a macroscopic entangled state between the two TLRs.

关键词： cross-Kerr-like interaction circuit quantum electrodynamics macroscopic entangled state