|
The quest for Anderson localization of light is at the center of many experimental and theoretical activities. Atomic vapors play a particular role in this research field, as they show a number of specific properties that make them quite different from other materials used to look for Anderson localization. The very narrow resonance of the atomic line, the mechanical effects of the light on the atoms and the potential for quantum features of these scatterers call for more detailed analysis of the behavior of light in large and dense samples of cold atoms. Photon propagation in a gas of N atoms is studied using an effective Hamiltonian describing photon-mediated atomic dipolar interactions. The density P(&Gamma) of photon escape rates is determined from the spectrum of the NxN random matrix. Varying disorder and system size, a scaling behavior is observed for the escape rates. Cooperative scattering of light by an extended object such as an atomic ensemble or a dielectric sphere is fundamentally different from scattering from many pointlike scatterers such as single atoms. Homogeneous distributions tend to scatter cooperatively, whereas fluctuations of the density distribution increase the disorder and suppress cooperativity. |
|