Intensity correlations and mesoscopic fluctuations of diffusing photons in cold atoms

TL;DR

This paper investigates mesoscopic intensity fluctuations in speckle patterns from cold atomic clouds, revealing enhanced correlations due to atom-photon interactions, distinct from classical scatterers, with theoretical expressions for experimental comparison.

Contribution

It introduces a new mesoscopic interference effect specific to atom-photon interactions, expanding understanding beyond classical scattering systems.

Findings

Correlation function exceeds Rayleigh law predictions

Large intensity fluctuations are observed in cold atom scattering

Theoretical expressions enable quantitative experimental comparison

Abstract

We study the angular correlation function of speckle patterns that result from multiple scattering of photons by cold atomic clouds. We show that this correlation function becomes larger than the value given by Rayleigh law for classical scatterers. These large intensity fluctuations constitute a new mesoscopic interference effect specific to atom-photon interactions, that could not be observed in other systems such as weakly disordered metals. We provide a complete description of this behavior and expressions that allow for a quantitative comparison with experiments.