LKB - Complex Quantum Systems


Coherent backscattering, Slow light, Dispersion forces

Light scattering from cold atoms


Light_scattering_from_cold_atomsLight propagating in a cold atomic gas can undergo multiple scattering. The peculiarity of such a system is the strongly quantum and resonant nature of the scatterers (the atoms), which gives rise to original physical phenomena like diffusive transport at low velocity, fast coherent light emission or cooperative scattering [1].
Under certain conditions, the light excitation can also saturate atomic transitions, which induces a nonlinear dynamics that can dramatically affect interference effects in disorder. A few years ago, we developed pioneering theoretical approaches allowing to account for the interplay between disorder and nonlinearity in these systems, in particular in the description of coherent backscattering.
Last, but not least, in dense clouds the propagating light can induce dipole atomic interactions. In turn, those can affect significantly the light transport [2], leading to the emergence of collective phenomena that can even challenge the very existence of Anderson localization.