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arXiv 1409.4586cond-mat.stat-mech
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遍历连续时间随机游动中平衡律附近的涨落

Fluctuations around equilibrium laws in ergodic continuous-time random walks

Johannes H. P. Schulz, Eli Barkai

摘要:

研究了遍历连续时间随机游动中的占有时间统计量。在热细致平衡条件下,平均占据时间由Boltzmann-Gibbs正则定律给出。但接近非遍历阶段,在这个平均值附近的有限时间波动是大的和非平凡的。它们表现出双重时间标度和分布律:大波动的无限密度补充了体波动的Lévy稳定密度。两者都不应该被解释为一个独立的极限定律,因为每一个都有自己的缺陷:无限密度有一个无限的范数(尽管粒子守恒),而稳定分布有一个无限的方差(尽管占据时间是有界的)。这些非物质的分歧是通过对两个公式的一致使用和解释来弥补的。有趣的是,虽然系统的正则平衡定律自然地决定了遍历运动的平均占据时间,但它们也控制了涨落的无穷大和列维稳定密度。稳定和无限密度的对偶性实际上在这些动力学中无处不在,因为它涉及一般物理观测量的时间平均。

英文摘要:

We study occupation time statistics in ergodic continuous-time random walks. Under thermal detailed balance conditions, the average occupation time is given by the Boltzmann-Gibbs canonical law. But close to the non-ergodic phase, the finite-time fluctuations around this mean are large and nontrivial. They exhibit dual time scaling and distribution laws: the infinite density of large fluctuations complements the Lévy-stable density of bulk fluctuations. Neither of the two should be interpreted as a stand-alone limiting law, as each has its own deficiency: the infinite density has an infinite norm (despite particle conservation), while the stable distribution has an infinite variance (although occupation times are bounded). These unphysical divergences are remedied by consistent use and interpretation of both formulas. Interestingly, while the system's canonical equilibrium laws naturally determine the mean occupation time of the ergodic motion, they also control the infinite and Lévy-stable densities of fluctuations. The duality of stable and infinite densities is in fact ubiquitous for these dynamics, as it concerns the time averages of general physical observables.

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