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arXiv 1010.4673cond-mat.stat-mechmath-phmath.MPquant-ph
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传统微正则系综的一种替代方法

An alternative to the conventional micro-canonical ensemble

Boris V. Fine, Frank Hantschel

摘要:

量子统计物理学的基本方法是以传统的微正则系综为出发点,导出玻尔兹曼-吉布斯(BG)平衡。然而,它留下了一些概念和实际问题没有回答。在这里,我们讨论这些问题,从而激发了一个自然的替代称为量子微正则(QMC)系综的研究。我们提出了一个详细的数值研究的性质的QMC系综有限量子系统揭示了一个很好的协议与现有的分析结果的大量子系统。我们还提出了引入有限尺寸效应的分析修正的方法。经过上述修正后,分析结果与数值结果之间的一致性变得非常精确。QMC系综导致了一种非常规的平衡,这可能是在具有大量能级的小孤立量子系统中在强扰动后实现的。我们证明了能量涨落的方差可以用来区分QMC平衡和BG平衡。我们进一步指出,自然界中普遍存在BG平衡而不是QMC型平衡的原因与量子坍缩的概念有关。

英文摘要:

Usual approach to the foundations of quantum statistical physics is based on conventional micro-canonical ensemble as a starting point for deriving Boltzmann-Gibbs (BG) equilibrium. It leaves, however, a number of conceptual and practical questions unanswered. Here we discuss these questions, thereby motivating the study of a natural alternative known as Quantum Micro-Canonical (QMC) ensemble. We present a detailed numerical study of the properties of the QMC ensemble for finite quantum systems revealing a good agreement with the existing analytical results for large quantum systems. We also propose the way to introduce analytical corrections accounting for finite-size effects. With the above corrections, the agreement between the analytical and the numerical results becomes very accurate. The QMC ensemble leads to an unconventional kind of equilibrium, which may be realizable after strong perturbations in small isolated quantum systems having large number of levels. We demonstrate that the variance of energy fluctuations can be used to discriminate the QMC equilibrium from the BG equilibrium. We further suggest that the reason, why BG equilibrium commonly occurs in nature rather than the QMC-type equilibrium, has something to do with the notion of quantum collapse.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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