Bragg scattering from a random potential

TL;DR

This paper demonstrates that a two-dimensional wave propagating through a randomly constructed potential exhibits sharp Bragg diffraction patterns, similar to powder diffraction, despite the absence of periodicity.

Contribution

It introduces a novel random potential model that produces observable Bragg scattering, challenging the assumption that such diffraction requires periodic structures.

Findings

Sharp Bragg diffraction observed in random potentials

Diffraction pattern analogous to powder diffraction

Phenomenon is partially resonant, not explained by Fermi's golden rule

Abstract

A potential for propagation of a wave in two dimensions is constructed from a random superposition of plane waves around all propagation angles. Surprisingly, despite the lack of periodic structure, sharp Bragg diffraction of the wave is observed, analogous to a powder diffraction pattern. The scattering is partially resonant, so Fermi's golden rule does not apply. This phenomenon would be experimentally observable by sending an atomic beam into a chaotic cavity populated by a single mode laser.