Nonequilibrium Langevin Approach to Quantum Optics in Semiconductor   Microcavities
  Recently the possibility of generating nonclassical polariton states by means of parametric scattering has been demonstrated. Excitonic polaritons propagate in a complex interacting environment and contain real electronic excitations subject to scattering events and noise affecting quantum coherence and entanglement. Here we present a general theoretical framework for the realistic investigation of polariton quantum correlations in the presence of coherent and incoherent interaction processes. The proposed theoretical approach is based on the {\em nonequilibrium quantum Langevin approach for open systems} applied to interacting-electron complexes described within the dynamics controlled truncation scheme. It provides an easy recipe to calculate multi-time correlation functions which are key-quantities in quantum optics. As a first application, we analyze the build-up of polariton parametric emission in semiconductor microcavities including the influence of noise originating from phonon induced scattering. 
S. Portolan (1,3), O. Di Stefano (2), S. Savasta (2), F. Rossi (3), R.   Girlanda (2), ((1) Institute of Theoretical Physics...