Statistical Scattering of Waves in Disordered Waveguides: from Microscopic Potentials to Limiting Macroscopic Statistics

TL;DR

This paper develops a statistical framework for wave scattering in disordered waveguides, deriving a universal diffusion equation for transport properties that accounts for microscopic potentials and their macroscopic limits.

Contribution

It introduces a generalized central-limit theorem and a diffusion equation for transfer matrices, incorporating energy effects in disordered waveguide scattering analysis.

Findings

Universal dependence on mean free paths in dense-weak-scattering limit

Derivation of a diffusion equation for transfer matrices

Inclusion of incident particle energy in the analysis

Abstract

We study the statistical properties of wave scattering in a disordered waveguide. The statistical properties of a "building block" of length (delta)L are derived from a potential model and used to find the evolution with length of the expectation value of physical quantities. In the potential model the scattering units consist of thin potential slices, idealized as delta slices, perpendicular to the longitudinal direction of the waveguide; the variation of the potential in the transverse direction may be arbitrary. The sets of parameters defining a given slice are taken to be statistically independent from those of any other slice and identically distributed. In the dense-weak-scattering limit, in which the potential slices are very weak and their linear density is very large, so that the resulting mean free paths are fixed, the corresponding statistical properties of the full waveguide depend only on the mean free paths and on no other property of the slice distribution. The universality that arises demonstrates the existence of a generalized central-limit theorem. Our final result is a diffusion equation in the space of transfer matrices of our system, which describes the evolution with the length L of the disordered waveguide of the transport properties of interest. In contrast to earlier publications, in the present analysis the energy of the incident particle is fully taken into account.