Phase coherence times in the multiple scattering of photons by cold atoms

摘要

We present an analysis of the dephasing present in the multiple scattering ofphotons by atoms with a quantum internal structure. The corresponding phasecoherence times $\tau_{\phi}$ are obtained as a function of the Zeemandegeneracy of the atomic dipole transition and the polarization state of thephotons. These results allow for an explanation of the recent experiments oncoherent backscattering of photons from a gas of cold rubidium atoms where theheight of the backscattering cone depends on the atomic internal degrees offreedom coupled to the polarization of the photons. Some consequences of theseresults are presented, and analogies with the case of electronic systems arehighlighted.