Flux conservation in coherent backscattering and weak localisation of light

TL;DR

This paper addresses flux conservation issues in coherent backscattering and weak localisation of light, proposing a unified framework that ensures flux conservation and corrects previous theoretical inconsistencies.

Contribution

It introduces a unified approach to treat coherent backscattering and weak localisation, restoring flux conservation in the theoretical description.

Findings

Flux conservation is explicitly demonstrated in leading order.

Including a single additional scattering event does not restore flux conservation.

A unified framework successfully enforces flux conservation.

Abstract

The standard theoretical description of coherent backscattering, accord- ing to which maximally crossed diagrams accounting for interference between counter- propagating path amplitudes are added on top of the incoherent background, violates the fundamental condition of flux conservation. In contrast to predictions of previous theories, we show that including maximally crossed diagrams with one additional scat- tering event does not restore flux conservation. Instead, we propose that the latter is recovered when treating the effects of coherent backscattering and weak localisation in a unified framework. On the basis of this framework, we demonstrate explicitly flux conservation in leading order of the weak disorder parameter 1/(kl).