arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1004.3667cond-mat.stat-mech
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随机游走熵的各个方面

The various facets of random walk entropy

Z. Burda, J. Duda, J. M. Luck, B. Waclaw

摘要:

我们回顾了图上随机路的统计特性。路径统计和量子力学之间的关系导致了定义图上随机游动的两种规范方法,它们具有不同的统计,因此具有不同的熵。一般随机游走(GRW)是对应于场论的形式主义,而最大熵随机游走(MERW),我们在最近的工作中介绍,是出于费曼路径积分公式的QM。GRW在局部最大化熵(以相等的概率选择邻居),而MERW在全局最大化熵(所有给定长度和端点的路径都是相等的概率)。MERW的稳定分布由量子力学问题的基态给出,其中度小于平均值的节点充当排斥杂质。我们调查静态和动态性能GRW和MERW在各种例子中的一个和两个维度。最引人注目的区别出现在弱稀释晶格的情况下,其中执行MERW的粒子最终被困在最大的接近球形的区域中,该区域没有杂质。我们提出了一个定量的解释,这种本地化效应的一个经典的Lifshitz现象。

英文摘要:

We review various features of the statistics of random paths on graphs. The relationship between path statistics and Quantum Mechanics (QM) leads to two canonical ways of defining random walk on a graph, which have different statistics and hence different entropies. Generic random walk (GRW) is in correspondence with the field-theoretical formalism, whereas maximal entropy random walk (MERW), introduced by us in a recent work, is motivated by the Feynman path-integral formulation of QM. GRW maximizes entropy locally (neighbors are chosen with equal probabilities), in contrast to MERW which does so globally (all paths of given length and endpoints are equally probable). The stationary distribution for MERW is given by the ground state of a quantum-mechanical problem where nodes whose degree is smaller than average act as repulsive impurities. We investigate static and dynamical properties GRW and MERW in a variety of examples in one and two dimensions. The most spectacular difference arises in the case of weakly diluted lattices, where a particle performing MERW gets eventually trapped in the largest nearly spherical region which is free of impurities. We put forward a quantitative explanation of this localization effect in terms of a classical Lifshitz phenomenon.

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