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arXiv 2202.02504cond-mat.stat-mech
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布朗量子振子自由能的分解:耗散和磁场的影响

Partition of free energy for a Brownian quantum oscillator: Effect of dissipation and magnetic field

Jasleen Kaur, Aritra Ghosh, Malay Bandyopadhyay

摘要:

近年来,能量均分定理的量子对应定理引起了人们的广泛关注。受此启发,我们制定和调查的自由能的量子振荡器线性耦合到一个被动的热浴由无限多个独立的谐振子的类似的声明。我们明确地表明,布朗振荡器的自由能可以表示为$F(T) = \langle f(ω,T) \rangle $的形式,其中$f(ω,T)$是一个单独的浴振荡器的自由能。整个平均过程涉及两个不同的平均:第一个是在浴振荡器的正则系综上,而第二个表示在从零到无穷大的整个浴频谱上的平均。后者是在相关的概率分布函数$\mathcal{P}(ω)$上进行的,该概率分布函数可以从线性响应理论中遇到的广义磁化率的知识中导出。不同的耗散机制的效果也表现出来。我们发现我们的结果的两个显着的后果。首先,能量均分定理的量子对应物自然地从我们的分析中得出。我们得到的第二个推论是开放量子系统热力学第三定律的自然推导。最后,我们推广到三维空间的形式存在的外部磁场。

英文摘要:

Recently, the quantum counterpart of energy equipartition theorem has drawn considerable attention. Motivated by this, we formulate and investigate an analogous statement for the free energy of a quantum oscillator linearly coupled to a passive heat bath consisting of an infinite number of independent harmonic oscillators. We explicitly demonstrate that the free energy of the Brownian oscillator can be expressed in the form $F(T) = \langle f(ω,T) \rangle $ where $f(ω,T)$ is the free energy of an individual bath oscillator. The overall averaging process involves two distinct averages: the first one is over the canonical ensemble for the bath oscillators, whereas the second one signifies averaging over the entire bath spectrum of frequencies from zero to infinity. The latter is performed over a relevant probability distribution function $\mathcal{P}(ω)$ which can be derived from the knowledge of the generalized susceptibility encountered in linear response theory. The effect of different dissipation mechanisms is also exhibited. We find two remarkable consequences of our results. First, the quantum counterpart of energy equipartition theorem follows naturally from our analysis. The second corollary we obtain is a natural derivation of the third law of thermodynamics for open quantum systems. Finally, we generalize the formalism to three spatial dimensions in the presence of an external magnetic field.

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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