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arXiv 1001.0841cond-mat.dis-nn
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无序多通道系统中的反常扩散

Anomalous diffusion in disordered multi-channel systems

R. Juhász, F. Iglói

摘要:

我们研究了粒子在由K个平行通道组成的系统中的扩散,其中通道内的跃迁速率是猝灭的随机变量,而通道间的跃迁速率v是均匀的。强无序重整化群方法和蒙特卡罗模拟的一个变种。通常,我们观察到反常扩散,其中粒子的平均行进距离[<x(t)>]_{av}具有幂律时间依赖性[<x(t)>]_{av} ~ t^{μ_K(v)},扩散指数为0 \le μ_K(v)\le 1。在随机速率分布存在左右对称性的情况下,多通道系统的回归点与K无关,扩散指数随K增大而随v减小。在不存在这种对称性的情况下,回归点可以随K移动,通过改变换道速率v可以使电流反向。

英文摘要:

We study diffusion of a particle in a system composed of K parallel channels, where the transition rates within the channels are quenched random variables whereas the inter-channel transition rate v is homogeneous. A variant of the strong disorder renormalization group method and Monte Carlo simulations are used. Generally, we observe anomalous diffusion, where the average distance travelled by the particle, [<x(t)>]_{av}, has a power-law time-dependence [<x(t)>]_{av} ~ t^{μ_K(v)}, with a diffusion exponent 0 \le μ_K(v) \le 1. In the presence of left-right symmetry of the distribution of random rates, the recurrent point of the multi-channel system is independent of K, and the diffusion exponent is found to increase with K and decrease with v. In the absence of this symmetry, the recurrent point may be shifted with K and the current can be reversed by varying the lane change rate v.

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