Angular correlation of photons emitted from an excited quantum well

We study the angular correlation of single photons emitted from excited semiconductor quantum wells. The considered physical system is described in terms of two subsystems, the electronic part constituting the bath and the photonic part constituting the bathed subsystem, both being coupled by the light-matter interaction. From the master equations describing the coarse-grained Markovian evolution of the photonic subsystem, we derive the corresponding equations of motion for the photonic angular correlation functions. These equations are solved in the stationary, low-density limit. Experimentally, the angular correlations can be assessed by studying the interference of light emitted in different directions. In agreement with recent experimental results, we find that for ordered quantum wells angular correlations exist only in emission directions for which the projections of the photon momenta onto the plane of the quantum well are equal. This feature is a direct consequence of the Bloch character of the electronic states in an ordered quantum well. Thus the experimental study of the angular correlations of emitted photons may provide an interesting diagnostic tool to reveal the presence of disorder in semiconductor heterostructures and to characterize its influence on the electronic states near the band edges.