Multiple scattering of light in cold atomic clouds with a magnetic field

TL;DR

This paper develops a microscopic theory for light scattering in cold atomic clouds under magnetic fields, revealing how magnetic fields can enhance coherent backscattering contrast, validated by experimental data.

Contribution

It introduces a non-perturbative theoretical framework for magneto-optical effects in cold atomic clouds, including the impact of magnetic fields on multiple scattering and CBS contrast.

Findings

Magnetic fields can increase CBS interference contrast in atomic clouds.

Theoretical results match experimental observations quantitatively.

Magnetic effects induce optical anisotropy in the scattering process.

Abstract

Starting from a microscopic theory for atomic scatterers, we describe the scattering of light by a single atom and study the coherent propagation of light in a cold atomic cloud in the presence of a magnetic field B in the mesoscopic regime. Non-pertubative expressions in B are given for the magneto-optical effects and optical anisotropy. We then consider the multiple scattering regime and address the fate of the coherent backscattering (CBS) effect. We show that, for atoms with nonzero spin in their ground state, the CBS interference contrast can be increased compared to its value when B=0, a result at variance with classical samples. We validate our theoretical results by a quantitative comparison with experimental data.