Mesoscopic physics of photons

Abstract

We review the general features of coherent multiple scattering of electromagnetic waves in random media. In particular, coherent backscattering and angular correlation functions of speckle patterns are studied in some detail. We present a general formalism based on a physically intuitive description that also permits us to derive quantitative expressions. Then, the notion of phase boxes describing the quantum crossings of diffusons is discussed. This notion permits us to understand the long-range correlations that are at the origin of most of the mesoscopic effects either for electrons or photons. Then, we turn to the problem of decoherence, namely, the washing out of interference effects. We use as an example the effect of a nondeterministic motion of the scatterers. We discuss some applications of these ideas to diffusive wave spectroscopy, including calculations of the intensity–time correlation function in the presence of quantum crossings.