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Nonlinear Waves in a Cigar-Shaped bose-einstein condensate with Dissipation

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Communications in Theoretical Physics 2008年第1期49卷 119-122页

作者： YANG Xiao-Xian SHI Yu-Ren DUAN Wen-Shan College of Physics and Electronic Engineering Northwest Normal University Lanzhou 730070 China

We discuss the possible nonlinear waves of atomic matter waves in a cigar-shaped bose-einstein condensatewith dissipation. The waves can be described by a KdV-type equation. The KdV-type equation has a solitary wave solution. The amplitude, speed, and width of the wave vary exponentially with time t. The dissipative term of ~/ plays an important role for the wave amplitude, speed, and width. Comparisons have been given between the analytical solutions and the numerical results. It is shown that both are in good agreement.

关键词： bose einstein condensate GP equation KdV-type equation

Spin-orbit coupling in bose-einstein condensate and degenerate Fermi gases

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Frontiers of physics 2014年第5期9卷 598-612页

作者： Peng-Jun Wang Jing Zhang State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-Electronics Shanxi University Taiyuan 030006 China

We review our recent experimental realization and investigation of a spin orbit （SO） coupled bose einstein condensate （BEC） and quantum degenerate Fermi gas. By using two counter-propagathlg Ranlan lasers and controlling the different frequency of two R,aman lasers to engineer the atom light interaction, we first study the SO coupling in BEC. Then we study SO coupling in Fermi gas. We, observe the spin dephasing in spin dynamics and momentum distribution asymmetry of the equilibrium state as halhnarks of SO coupling in a Fermi gas. To clearly reveal the, property of SO coupling Fermi gas, we also study the momentmn-resolved radio-frequency spectroscopy which characterizes the energy momentum dispersion and spin composition of the quantum states. We observe the change of errmion surfaces in different helieity branches with different atomic density, which indicates that a Lifshitz transition of the Fermi surface topology change can be found by further cooling the system. At last, we study the momentum-resolved Raman spectroscopy of an ultracoht Fermi gas.

关键词： spin-orbit coupling bose einstein condensate Fermi gases topological change momentum-resolved radio-frequency spectroscopy momentum-resolved Raman spectroscopy

Effects of Spatial Noncommutativity on Energy Spectrum of a Trapped bose-einstein condensate

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Communications in Theoretical Physics 2006年第6X期46卷 966-968页

作者： LUO You-Hua GE Zi-Ming Institute for Theoretical Physics and Department of Physics East China University of Science and Technology Shanghai 200237 China

In noncommutative space, we examine the problem of a noninteracting and harmonically trapped bose- einstein condensate, and derive a simple analytic expression for the effect of spatial noncommutatlvity on energy spectrum of the condensate, it indicates that the ground-state energy incorporating the spatial noncommutativity is reduced to a lower level, which depends upon the noncommutativity parameter 8. The gap between the noncommutative space and commutative one for the ground-state level of the condensate should be a signal of spatial noncommutativity.

关键词： spatial noncommutativity energy spectrum bose einstein condensate

Probability of Obtaining the Planck Constant, in a Universe Modeled as a Giant Black Hole by bose einstein condensates of Gravitons Using Hawking Argument and Scaling

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Journal of High Energy Physics, Gravitation and Cosmology 2023年第1期9卷 134-141页

作者： Andrew Walcott Beckwith Physics department Chongqing University Chongqing China

We use the methodology of A. D. Linde to model the probability of obtaining a cosmological constant which is in turn affected by scaling arguments for a bose einstein gravitational condensate as given by Chavanis, in 2015. The net result, is that the scaling argument so provided allows for a gravitational constant commensurate with the size of the Universe, using arguments which appear to be simple but which give, if one has the conditions for modeling the Universe as a “black hole” virtually 100 % chance for the cosmological constant arising.

关键词： Black Hole bose einstein condensate Planck Constant Massive Graviton Hubble Parameter

bose-einstein condensation on an atom chip

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Chinese Physics B 2009年第10期18卷 4259-4263页

作者：颜波程峰柯敏李晓林唐九耀王育竹 Key Laboratory for Quantum Optics Center for Cold Atom Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Department of Physics Zhejiang University

This paper reports an experiment of creating bose-einstein condensate （BEC） on an atom chip. The chip-based Z-wire current with a homogeneous bias magnetic field creates a tight magnetic trap, which allows for a fast production of BEC. After a 4.17-s forced radio frequency evaporative cooling, a condensate with about 3000 atoms appears. The transition temperature is about 300 nK. This compact system is quite robust, allowing for versatile extensions and further studying of BEC.

关键词： bose einstein condensate atom chip

Radio-frequency spectroscopic measurement for pairing gap in an ultracold Fermi gas

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Science China(Physics,Mechanics & Astronomy) 2013年第3期56卷 581-587页

作者： JIANG KaiJun LUO Hua LI Kai ZHANG DongFang GAO TianYou PENG ShiGuo State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsChinese Academy of Sciences

The study of ultracold Fermi gases has exploded a variety of experimental and theoretical research since the achievement of degenerate quantum gases in the lab,which expands the research range over atomic physics,condensed matter physics,astrophysics and particle *** the Feshbach resonance,one can tune the attractive two-body interaction from weak to strong and thereby make a smooth crossover from the BCS superfluid of cooper pairs to the bose einstein condensate of bound *** this crossover regime,the pairing effect plays a significant role in interpreting the interaction *** the localized or delocalized pairing occurs at sufficiently low temperature,the single-particle energy will shift with respect to free atoms,due to the two-body or many-body *** the pairing gap can improve the understanding of the thermodynamics and hydrodynamics of the phase transition from the pseudogap to the superfluid,which will make an analogue to the high-temperature superconductivity in condensed *** this work,we will give a brief introduction to a novel radio-frequency(RF) spectroscopic measurement for pairing gap in an ultracold Fermi gas,which is currently widely used on the ultracold atomic table in the *** different interaction regimes of the BEC-BCS crossover,ultracold atoms are excited with a RF pulse and the characteristic behavior can be extracted from the spectrum.

关键词： degenerate Fermi gas Feshbach resonance bose einstein condensate superfluid

Nonlinear quantum interferometry with bose condensed atoms

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Frontiers of physics 2012年第1期7卷 109-130页

作者： Chaohong Lee (1) Jiahao Huang (1) Haiming Deng (1) Hui Dai (1) Jun Xu (1) 1. State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and Engineering Sun Yat-Sen University Guangzhou 510275 China

In quantum interferometry, it is vital to control and utilize nonlinear interactions for the achievement of high-precision measurements. Due to their long coherence time and high controllability, ultracold atoms including bose condensed atoms have been widely used for quantum interferometry. Here, we review recent progress in theoretical studies of quantum interferometry with bose condensed atoms. In particular, we focus on nonlinear phenomena induced by atom-atom interactions, and how to control and utilize these nonlinear phenomena. With a mean-field description, due to atom-atom interactions, matter-wave solitons appear in the interference patterns, and macroscopic quantum self-trapping exists in bose-Josephson junctions. With a many-body description, atom-atom in- teractions can generate non-classical entanglement, which can be utilized to achieve high-precision measurements beyond the standard quantum limit.

关键词： nonlinear quantum interferometry bose einstein condensate bose-Josephson junction

Two-dimensional matter-wave solitons and vortices in competing cubic-quintic nonlinear lattices

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Frontiers of physics 2018年第1期13卷 153-161页

作者： Xuzhen Gao Jianhua Zeng State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics of CAS Xi'an 710119 China University of Chinese Academy of Sciences Beijing 100084China

The nonlinear lattice - a new and nonlinear class of periodic potentials - was recently introduced to generate various nonlinear localized modes. Several attempts failed to stabilize two-dimensional （2D） solitons against their intrinsic critical collapse in Kerr media. Here, we provide a possibility for supporting 2D matter-wave solitons and vortices in an extended setting - the cubic and quintic model - by introducing another nonlinear lattice whose period is controllable and can be different from its cubic counterpart, to its quintic nonlinearity, therefore making a fully ＂nonlinear quasi-crystal＂. A variational approximation based on Gaussian ansatz is developed for the fundamental solitons and in particular, their stability exactly follows the inverted Vakhitov-Kolokolov stability criterion, whereas the vortex solitons are only studied by means of numerical methods. Stability regions for two types of localized mode -- the fundamental and vortex solitons -- are provided. A noteworthy feature of the localized solutions is that the vortex solitons are stable only when the period of the quintic nonlinear lattice is the same as the cubic one or when the quintic nonlinearity is constant, while the stable fundamental solitons can be created under looser conditions. Our physical setting （cubic-quintic model） is in the framework of the Gross-Pitaevskii equation or nonlinear Schr6dinger equation, the predicted localized modes thus may be implemented in bose-einstein condensates and nonlinear optical media with tunable cubic and quintic nonlinearities.

关键词： soliton vortex bose einstein condensate periodic potential

Controlling the Collision Between Two Solitons in a Two-Component condensate by Interspecies Interactions

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Communications in Theoretical Physics 2011年第9期56卷 440-444页

作者：张志强王登龙罗晓清丁建文 Department of Physics the Key Laboratory of Quantum Engineering and Micro-Nano Energy Technology of the Education Bureau of Hunan ProvinceXiangtan University

We present a family of the solutions of two-component bose-einstein condensates with time-dependentscattering length by means of multiple-scale *** numerical calculations show that the collision properties (theposition,the time,and the frequency of the collision) between two solitons can be controlled by the time-dependentinterspecies scattering ***,we also find that the amplitude of the solitons is close related to the timedependentinterspecies scattering length.

关键词： bose einstein condensate soliton interspecies scattering length