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Nonautonomous deformed solitons in a Bose-Einstein condensate

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Chinese Physics B 2013年第9期22卷 335-341页

作者：李泽军海文华邓艳 Department of Physics and key laboratory of low-dimensional quantum Structure and quantum control of ministry of education Hunan Normal University

We study exact single-soliton solutions of an attractive Bose-Einstein condensate governed by a one-dimensional nonautonomous Gross-Pitaevskii system. For several different forms of time-dependent atom-atom interaction and external parabolic potential which satisfy the exact integrability scenario, we construct a set of new analytical nonautonomous deformed-soliton solutions, including the macroscopic wave function and the position of soliton＇s center of mass. The soliton characteristics are modulated by the external field parameters and deformation factors related to the number of the condensed atoms and the initial conditions. The results suggest a simple and effective method for experimentally generating matter-wave deformed solitons and manipulating their motions.

关键词： Bose-Einstein condensate nonautonomous system deformed soliton

Nonlinear Dicke quantum Phase Transition and Its quantum Witness in a Cavity-Bose–Einstein-Condensate System

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Chinese Physics Letters 2018年第11期35卷 61-65页

作者： Wang-Jun Lu Zhen Li Le-Man Kuang key laboratory of low-dimensional quantum structures and quantum control(ministry of education) Department of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal University

We investigate nonlinear Dicke quantum phase transition(QPT)induced by inter-atomic nonlinear interaction and its quantum witness in a cavity-Bose–Einstein-condensate(BEC)*** is shown that inter-atomic nonlinear interaction in a cavity BEC system can induce first-order Dicke *** is found that this nonlinear Dicke QPT can happen in an arbitrary coupling regime of the cavity and *** is demonstrated that the quantum speed limit time can witness the Dicke QPT through its sudden change at the critical point of the QPT.

关键词： Atoms

quantum speed limit time of a two-level atom under different quantum feedback control

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Chinese Physics B 2018年第1期27卷 253-257页

作者：余敏方卯发邹红梅 Department of Physics Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Educationand Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University

We investigate the quantum speed limit time （QSLT） of a two-level atom under quantum-jump-based feedback control or homodyne-based feedback control. Our results show that the two different feedback control schemes have different influences on the evolutionary speed. By adjusting the feedback parameters, the quantum-jump-based feedback control can induce speedup of the atomic evolution from an excited state, but the homodyne-based feedback control cannot change the evolutionary speed. Additionally, the QSLT for the whole dynamical process is explored. Under the quantum-jump-based feedback control, the QSLT displays oscillatory behaviors, which implies multiple speed-up and speed-down processes during the evolution. While, the homodyne-based feedback control can accelerate the speed-up process and improve the uniform speed in the uniform evolution process.

关键词： quantum speed limit time quantum feedback control speedup

Confined states and spin polarization on a topological insulator thin film modulated by an electric potential

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Chinese Physics B 2013年第7期22卷 478-483页

作者：刘一曼邵怀华周小英周光辉 Department of Physics and key laboratory for low-dimensional structures and quantum Manipulation (ministry of education) Hunan Normal University

We study the electronic structure and spin polarization of the surface states of a three-dimensional topological insulator thin film modulated by an electrical potential well. By routinely solving the low-energy surface Dirac equation for the system, we demonstrate that confined surface states exist, in which the electron density is almost localized inside the well and exponentially decayed outside in real space, and that their subband dispersions are quasilinear with respect to the propagating wavevector. Interestingly, the top and bottom surface confined states with the same density distribution have opposite spin polarizations due to the hybridization between the two surfaces. Along with the mathematical analysis, we provide an intuitive, topological understanding of the effect.

关键词： topological insulator thin film electronic structure spin polarization electric potential

Electron states scattering off line edges on the surface of topological insulator

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Chinese Physics B 2014年第10期23卷 477-482页

作者：邵怀华刘一曼周小英周光辉 Department of Physics and key laboratory for low-dimensional structures and quantum Manipulation (ministry of education) Hunan Normal University

We study the local density of states （LDOS） for electrons scattering off the line edge of an atomic step defect on the surface of a three-dimensional （3D） topological insulator （TI） and the line edge of a finite 3D TI, where the front surface and side surface meet with different Fermi velocities, respectively. By using a S-function potential to model the edges, we find that the bound states existed along the step line edge significantly contribute to the LDOS near the edge, but do not modify the exponential behavior away from it. In addition, the power-law decaying behavior for LDOS oscillation away from the step is understood from the spin rotation for surface states scattering off the step defect with magnitude depending on the strength of the potential. Furthermore, the electron refraction and total reflection analogous to optics occurred at the line edge where two surfaces meet with different Fermi velocities, which leads to the LDOS decaying behavior in the greater Fermi velocity side similar to that for a step line edge. However, in the smaller velocity side the LDOS shows a different decaying behavior as x-1/2, and the wavevector of LDOS oscillation is no longer equal to the diameter of the constant energy contour of surface band, but is sensitively dependent on the ratio of the two Fermi velocities. These effects may be verified by STM measurement with high precision.

关键词： topological insulator line defects local density of states

Possibilities for synthesis of new neutron-deficient isotopes of superheavy nuclei

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Chinese Physics C 2019年第5期43卷 70-80页

作者： Xiao-Jun Bao Department of Physics Collaborative Innovation Center for Quantum Effects and Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education Hunan Normal University

This study investigates the optimal projectile/target combination for the production of new neutron-deficient isotopes of superheavy nuclei(SHN). To this end, the dependence of the evaporation residue cross-section(ERCS) used to synthesize SHN on the mass asymmetry and the isospin of colliding nuclei are analyzed within the dinuclear system(DNS) concept. The predicted ERCSs for the production of new neutron-deficient isotopes of SHN were found to be quite large with the ^(36) S projectile, and the cross-section of SHN decreases slowly with the charge of compound nuclei owing to the increase in their survival probability,. Wsur is not canceled by the decreasing probability, PCN, that the system will evolve from a touching configuration to the compound nucleus in competition with the quasifission process.

关键词： new neutron deficient isotopes superheavy nuclei optimal projectile-target combination isospin effects

Enhanced Deflection of Light Ray by Atomic Ensemble on Coherent Population Oscillation

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Communications in Theoretical Physics 2009年第1期51卷 139-144页

作者： LU Jing ZHOU Lan KUANG Le-Man key laboratory of low-dimensional quantum structures and quantum control of ministry of education and Department of Physics Hunan Normal University Changsha 410081 China

In recent experiments [e.g., Nature Physics 2 （2006） 332], the enhanced light deflection in an atomic ensemble due to inhomogeneous fields is demonstrated by the electromagneticaJly induced transparency （EIT） based mechanism. In this paper, we explore a different mechanism for the similar phenomenon of the enhanced light deflection. This mechanism is based on the coherent population oscillation, which leads to the hole burning in the absorption spectrum. The medium causing the deflection of probe light is an ensemble of two-level atoms manipulated by a strong controlled field on the two photon resonances. In the large detuning condition, the response of the medium to the pump field and signal field is obtained with steady state approximation. And it is found that after the probe field travels across the medium, the signal ray bends due to the spatial-dependent profile of the control beam.

关键词： coherent population oscillation atomic response large detuning

Generation of three-mode W-type entangled coherent states in free-travelling optical fields

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Chinese Optics Letters 2008年第4期6卷 303-306页

作者：郭裕匡乐满 key laboratory of low-dimensional quantum structures and quantum control of ministry of education and Department of Physics Hunan Normal UniversityChangsha 410081 Department of Physics and Electronic ScienceChangsha University of Science and TechnologyChangsha 410076 key laboratory of low-dimensional quantum structures and quantum control of ministry of education and Department of Physics Hunan Normal UniversityChangsha 410081

We propose a scheme for generation of three-mode W-type entangled coherent states （ECSs） in freetravelling optical fields by using a single-photon source, coherent state sources, beam splitters, photodetectors, and three-mode cross-Kerr media. The scheme consists of a Mach-Zehnder interferometer （MZI） in which each arm contains a cross-Kerr medium. We calculate the success probability of the generated W-type ECSs, and the total success probability is unity under the ideal conditions.

关键词： Mach Zehnder interferometers Optical beam splitters Photodetectors quantum entanglement

Thermodynamic effects of Bardeen black hole surrounded by perfect fluid dark matter under general uncertainty principle

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Chinese Physics B 2022年第5期31卷 180-188页

作者： Zhenxiong Nie Yun Liu Juhua Chen Yongjiu Wang 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 410081China

The thermodynamics of Bardeen black hole surrounded by perfect fluid dark matter is *** calculate the analytical expresses of corresponding thermodynamic variables,e.g.,the Hawking temperature,entropy of the black *** addition,we derive the heat capacity to analyze the thermal stability of the black *** also compute the rate of emission in terms of photons through *** numerical method,an obvious phase transition behavior is ***,according to the general uncertainty principle,we study the quantum corrections to these thermodynamic quantities and obtain the quantum-corrected entropy containing the logarithmic ***,we investigate the effects of the magnetic charge g,the dark matter parameter k and the generalized uncertainty principle parameterαon the thermodynamics of Bardeen black hole surrounded by perfect fluid dark matter under general uncertainty principle.

关键词： general uncertainty principle quantum-corrected entropy phase transition