Microscopic theory of exciton coherent control and Rayleigh scattering in semiconductor quantum wells

We present a bosonic description of excitons created by means of resonant optical pumping in a quantum well in the presence of a weak disorder potential. The excitonic collective state is a Glauber coherent state, closely related to that of photons but substantially different from that of few-level models. The theory, applying to the low-density regime, is used to explain various transient linear optical experiments involving resonantly excited excitons in GaAs quantum wells. In particular, we consider coherent control of the exciton density and spin, resonant Rayleigh scattering and scattering coherent control. Our quantum mechanical approach for light emission shows that excitonic secondary emission has a coherent component, in agreement with experiments.