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 o ptical pumping in a quantum well in the presence of a weak disorder potenti al. The excitonic collective state is a Glauber coherent stair, closely rel ated 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 e xcitons in GaAs quantum wells. Tn particular, we consider coherent control of the exciton density and spin, resonant Rayleigh scattering and scatterin g coherent control. Our quantum mechanical approach for light emission show s that excitonic secondary emission has a coherent component, in agreement with experiments.