Intensity correlations to probe light scattering in optically thick cold atomic cloud

Mathilde Fouché
Université Côte d'Azur, INPHYNI, CNRS, 1361 route des lucioles, 06560 Valbonne, France

The study of fluctuations and correlations often gives access to information not contained in averaged values. Among the many statistical properties of a fluctuating field, the intensity correlation function is largely used in a number of areas, from astronomy, to quantum optics, particle physics, and to mesoscopic optics. In the latter, it has been applied to the fluctuations of light scattered by a disordered medium. First used in the single-scattering regime with a technique known as dynamic light scattering or quasielastic light scattering, it was then extended to strong multiple-scattering regime.

In this talk, I will present different results obtained with intensity correlation measurements on light scattered by a cold atomic cloud. We first applied this technique to cold atoms under purely ballistic motion and we investigate the transition between the single and the multiple-scattering regime. When the atoms are driven by a strong laser field, one measures the well-known Mollow triplet, a fundamental signature of quantum optics. Finally, by coupling the intensity correlation to the beat note technique, one has access to the first and second order correlation functions, allowing in particular to test the validity of the Siegert relation in different configurations.