On the Inequivalence of Weak-Localization and Coherent Backscattering

TL;DR

This paper demonstrates that weak localization effects in disordered systems are more complex than the coherent backscattering peak, involving additional diagrams that reduce the effect and have no semiclassical analogues, impacting theories of chaotic systems.

Contribution

The paper introduces a current-conserving approximation that reveals the non-equivalence of weak localization and coherent backscattering effects, highlighting additional contributing diagrams.

Findings

Weak localization is not solely due to the coherent backscattering diagram.

Additional diagrams reduce the weak localization correction.

Some contributing diagrams lack semiclassical analogues.

Abstract

We define a current-conserving approximation for the local conductivity tensor of a disordered system which includes the effects of weak localization. Using this approximation we show that the weak localization effect in conductance is not obtained simply from the diagram corresponding to the coherent back-scattering peak observed in optical experiments. Other diagrams contribute to the effect at the same order and decrease its value. These diagrams appear to have no semiclassical analogues, a fact which may have implications for the semiclassical theory of chaotic systems. The effects of discrete symmetries on weak localization in disordered conductors is evaluated and and compared to results from chaotic scatterers.