Weak localization of waves

Abstract

The weak localization of waves is formulated in terms of coherent multiple scattering theory. This leads, in the backscattering direction, to an enhancement of the differential cross-section. It manifests itself macroscopically by the doubling of the backscattering intensity in a narrow cone of width Φ c = λ/l . θ(Ω)/τ, where θ(Ω) is the residence time around the incident direction. The corrections to transport coefficients are then derived both in two and three dimensions in terms of Φc. An ε-expansion around the lower critical dimension dc = 2 is then performed and leads to a wave localization threshold for d > 2 around which the critical behaviour is studied. Different kinds of experimental situations leading to the observation of this backscattering cone and critical exponents are then discussed