Quantum versus classical statistical dynamics of an ultracold Bose gas
Quantum versus classical statistical dynamics of an ultracold Bose gas
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超冷玻色气体的量子与经典统计动力学
DOI：
10.1103/physreva.76.033604
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发表时间：
2007
影响因子：
2.9
通讯作者：
T. Gasenzer
中科院分区：
文献类型：
--
作者：
J. Berges;T. Gasenzer
我们研究了量子涨落与超冷玻色气体实验的定量解释相关的条件。这需要超越Gross-Pitaevskii和Hartree-Fock-Bogoliubov平均场理论的描述，这些平均场理论可以作为量子多体问题的经典(统计)场论近似。我们采用了基于两粒子不可约(2pi)有效作用量的泛函积分技术。在非微扰的2pi$1/数学{N}展开下，研究了量子涨落的作用。在这种精度水平下，记忆积分进入动态方程，对于量子统计描述和经典统计描述是不同的。这可以用来得到多体动力学的经典条件。我们通过研究钠原子一维玻色气体的非平衡演化来举例说明这一条件，并讨论了量子统计动力学与经典统计动力学的一些独特性质。
We investigate the conditions under which quantum fluctuations are relevant for the quantitative interpretation of experiments with ultracold Bose gases. This requires to go beyond the description in terms of the Gross-Pitaevskii and Hartree-Fock-Bogoliubov mean-field theories, which can be obtained as classical (statistical) field-theory approximations of the quantum many-body problem. We employ functional-integral techniques based on the two-particle irreducible (2PI) effective action. The role of quantum fluctuations is studied within the nonperturbative 2PI $1∕\mathcal{N}$ expansion to next-to-leading order. At this accuracy level memory integrals enter the dynamic equations, which differ for quantum and classical statistical descriptions. This can be used to obtain a classicality condition for the many-body dynamics. We exemplify this condition by studying the nonequilibrium evolution of a one-dimensional Bose gas of sodium atoms, and discuss some distinctive properties of quantum versus classical statistical dynamics.