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arXiv 2205.00549cond-mat.stat-mech
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随机重置对具有随机扩散系数的布朗运动的影响

Effect of stochastic resetting on Brownian motion with stochastic diffusion coefficient

Ion Santra, Urna Basu, Sanjib Sabhapandit

摘要:

研究了扩散系数随机演化的布朗运动的动力学。我们首先在任意维度上研究这个过程,找到位置分布的标度形式和相应的标度函数。我们发现,分布的尾部有指数尾部的弹道标度。然后,我们介绍了重置动态,在一个恒定的速率,位置和扩散系数重置为零。这最终导致了一个非平衡定态,我们在任意维的研究。与重置条件下的普通布朗运动形成鲜明对比的是,一维定态位置分布在原点处具有对数发散。然而,对于更高的维度,发散消失,分布在原点处达到一个依赖于维度的常数值,这是我们精确计算的。该分布在所有维度上都有一个通用的拉伸指数尾。我们还研究了到达定态的方法,发现随着时间的增加,原点周围的一个内部核心区域达到定态,而外部区域仍然具有瞬态分布--这个内部定态区域增长$\sim t^2$,即,以恒定的加速度,比普通的布朗运动快得多。

英文摘要:

We study the dynamics of a Brownian motion with a diffusion coefficient which evolves stochastically. We first study this process in arbitrary dimensions and find the scaling form and the corresponding scaling function of the position distribution. We find that the tails of the distribution have exponential tails with a ballistic scaling. We then introduce the resetting dynamics where, at a constant rate, both the position and the diffusion coefficient are reset to zero. This eventually leads to a nonequilibrium stationary state, which we study in arbitrary dimensions. In stark contrast to ordinary Brownian motion under resetting, the stationary position distribution in one dimension has a logarithmic divergence at the origin. For higher dimensions, however, the divergence disappears and the distribution attains a dimension-dependent constant value at the origin, which we compute exactly. The distribution has a generic stretched exponential tail in all dimensions. We also study the approach to the stationary state and find that, as time increases, an inner core region around the origin attains the stationary state, while the outside region still has a transient distribution -- this inner stationary region grows $\sim t^2$, i.e., with a constant acceleration, much faster than ordinary Brownian motion.

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