共查询到17条相似文献,搜索用时 171 毫秒
1.
李玉山 《原子与分子物理学报》2015,32(6)
基于Thomas-Fermi半经典近似方法研究了谐振子势阱约束下任意维理想玻色气体的玻色-爱因斯坦凝聚(BEC).导出了玻色气体的BEC转变温度、基态粒子占据比例、内能和热容量等物理量的解析表达式,讨论了空间维度和谐振子势阱的影响.以二维和三维玻色系统为例,数值计算了上述热力学量,并与解析结果进行了对比,二者获得了较好的吻合. 相似文献
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李玉山 《原子与分子物理学报》2014,31(4):683-686
基于Thomas-Fermi半经典近似研究了谐振子势阱约束下任意维理想玻色气体的玻色-爱因斯坦凝聚(BEC).导出了玻色气体的BEC转变温度、基态粒子占据比例、内能和热容量等物理量的解析表达式,讨论了空间维度和谐振子势阱的影响.以二维和三维玻色系统为例,数值计算了上述热力学量,并与解析结果进行了对比,二者获得了较好的吻合. 相似文献
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根据由赝势法得到的非理想玻色气体的自由能和状态方程,研究了相互作用对凝聚温度的影响.从热力学角度揭示了存在引力作用时定压热容量、等温压缩系数、定压膨胀系数的反常热力学特性.研究了引力作用下玻色气体系统的不稳定性,给出了不稳定性的温度判据和粒子数密度判据.
关键词:
相互作用
玻色气体
热力学性质
不稳定性判据 相似文献
4.
在定义特征长度的基础上,应用Euler–MacLaurin公式,研究了三维简谐势阱中有限理想Fermi气体的热力学性质.给出了具有有限尺度效应修正的化学势、内能、压强张量与状态方程和热容量的解析表达式,分别就强简并和弱简并的情况进行了讨论.揭示了简谐势阱中有限尺度效应的实质以及与处于D维容器中的不同,指出了简谐势阱中的有限尺度效应使得热力学量减小,压强的各向同性(或各向异性)取决于简谐势的各向同性(或各向异性),T=0K时费米能和基态内能在满足一定边界条件时分别存在一个极大值. 相似文献
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采用半经典近似方法,研究简谐势阱中二维理想带电玻色气体的磁性质.推导出了该体系的热力学势、相变温度、内能、比热、磁场强度和磁化率随外加磁场的变化关系,进而分析了约束势阱对理想带电玻色气体热力学性质的影响. 相似文献
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利用局域密度近似(LDA)导出了简谐势阱中存在弱相互作用的旋转玻色气体发生玻色-爱因斯坦凝聚时的粒子数、相变温度和基态粒子占据率的解析表达式,探讨了粒子间相互作用对相变温度和基态粒子占据率的影响.计算表明,当粒子间的相互作用消失时,所有解析结果均能够与无相互作用的旋转理想玻色气体获得很好的一致. 相似文献
10.
研究了玻色-费米超流混合体系中的相互作用调制隧穿动力学特性,其中玻色子位于对称双势阱中,费米子位于对称双势阱中心的简谐势阱中.采用双模近似方法得到描述双势阱玻色-爱因斯坦凝聚的动力学特性方程组,并将其与简谐势阱中分子玻色-爱因斯坦凝聚的Gross-Pitaevskii方程进行耦合.通过对不同参数下玻色-费米混合体系中的隧穿现象进行数值研究,发现简谐势阱中费米子与双势阱中玻色子的相互作用使双势阱玻色-爱因斯坦凝聚的隧穿动力学特性更加丰富.不但驱使双势阱中玻色-爱因斯坦凝聚从类约瑟夫森振荡转变为宏观量子自囚禁,而且宏观量子自囚禁表现为三种不同的形式:相位与时间呈负相关并随时间单调减小的自囚禁、相位随时间演化有界的自囚禁以及相位与时间呈正相关并随时间单调增大的自囚禁. 相似文献
11.
We present a theoretical study of Bose-Einstein condensation in highly anisotropic harmonic traps. The bosons are considered to be moving in an optical lattice in an overall anisotropic harmonic confining potential. We find that two-step condensation occurs for lattice bosons at much reduced harmonic potential anisotropy when compared to the case of an ideal Bose gas in an anisotropic harmonic confinement. We also show that when the bosons are in an isotropic harmonic confinement but with highly anisotropic hopping in the optical lattice, two-step condensation does not occur. We interpret some of our results using single boson density of energy states corresponding to the potentials faced by the bosons. 相似文献
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A simple and direct approach to handle summation is presented. With this approach, we analytically investigate Bose-Einstein condensation of ideal Bose gas trapped in an isotropic harmonic oscillator potential. We get the accurate expression of Tc which is very close to (0.43% larger than) the experimental data. We find the curve of internal energy of the system vs. temperature has a turning point which marks the beginning of a condensation. We also find that there exists specific heat jump at the transition temperature, no matter whether the system is macroscopic or finite. This phenomenon could be a manifestation of a phase transition in finite systems. 相似文献
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J.H. Wang J.Z. He 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(1):73-77
Based on the classification scheme of phase transitions, we study the phase transitions
for an ideal Bose gas with a finite number of particles confined in a three-dimensional
quartic trap. We show that the phase transition of an ideal Bose gas in the
three-dimensional quartic trap is of third order for finite particle numbers, quite
different from the fact that the phase transition is of first order in the thermodynamic
limit. We discuss the effects of finite particle numbers on the nature of the phase
transitions, and determine the dependence of transition temperature on particle number. 相似文献
14.
P.J. Forrester N.E. Frankel T.M. Garoni N.S. Witte 《Communications in Mathematical Physics》2003,238(1-2):257-285
The recent experimental realisation of a one-dimensional Bose gas of ultra cold alkali atoms has renewed attention on the
theoretical properties of the impenetrable Bose gas. Of primary concern is the ground state occupation of effective single
particle states in the finite system, and thus the tendency for Bose-Einstein condensation. This requires the computation
of the density matrix. For the impenetrable Bose gas on a circle we evaluate the density matrix in terms of a particular Painlevé
VI transcendent in Σ-form, and furthermore show that the density matrix satisfies a recurrence relation in the number of particles.
For the impenetrable Bose gas in a harmonic trap, and with Dirichlet or Neumann boundary conditions, we give a determinant
form for the density matrix, a form as an average over the eigenvalues of an ensemble of random matrices, and in special cases
an evaluation in terms of a transcendent related to Painlevé V and VI. We discuss how our results can be used to compute the
ground state occupations.
Received: 24 July 2002 / Accepted: 26 January 2003
Published online: 13 May 2003
Communicated by L. Takhtajan 相似文献
15.
本文从G-P平均势场理论出发,探讨了三维球对称非谐势阱中玻色-爱因斯坦凝聚(BEC)的G-P方程;用数值计算方法研究了三维球对称非谐势阱中原子间有相互作用的玻色-爱因斯坦凝聚气体的基态解;分析了非谐振势能项对玻色-爱因斯坦凝聚体的分布、能量和化学势的影响。 相似文献
16.
Effects of a finite number of particles on the thermodynamic properties of a harmonically trapped ideal charged Bose gas in a constant magnetic field 下载免费PDF全文
We investigate the thermodynamic properties of an ideal charged Bose gas confined in an anisotropic harmonic potential and a constant magnetic field. Using an accurate density of states, we calculate analytically the thermodynamic potential and consequently various intriguing thermodynamic properties, including the Bose–Einstein transition temperature, the specific heat, magnetization, and the corrections to these quantities due to the finite number of particles are also given explicitly. In contrast to the infinite number of particles scenarios, we show that those thermodynamic properties,particularly the Bose–Einstein transition temperature depends upon the strength of the magnetic field due to the finiteness of the particle numbers, and the collective effects of a finite number of particles become larger when the particle number decreases. Moreover, the magnetization varies with the temperature due to the finiteness of the particle number while it keeps invariant in the thermodynamic limit N →∞. 相似文献
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The ideal noninteracting Bose gases trapped in a generic power-law potential in an any-dimensional space are studied. We present theoretical results of the corrections of thermodynamic properties due to finite particle number effects. The calculation uses the Euler-Maclaurin approximation to simplify the condensate fraction, and it also uses the Maslov index to discuss the boundary effect. Recently BEC (Bose-Einstein Condensation) has also been observed in a microelectronic chip; therefore, with a similar microstructure, we can obtain the effects of a rigid wall in a trap that have never been found before.Received: 3 January 2003, Published online: 23 July 2003PACS:
05.30.-d Quantum statistical mechanics 相似文献