Experimental evidence for correlated polaritonic emission from a semiconductor microcavity

In this contribution, a novel geometry is investigated that eliminates the asymmetry between the signal and idler fields,using a nonlinear process that produces signal and idler polaritons with opposite wave vectors, hence the same photon content and the same linewidth, which allows maximal correlations between the signal and idler beams. It is studied theoretically in the Heisenberg-Langevin formalism and is found that perfect quantum correlations can be achieved for the polariton fields. The experimental observation of such nonlinear process is reported. A correlation of about 0.6 between the beams emitted with opposite planar wave vectors us measured. The measured correlations are classical, meaning that the intensity difference between the signal and idler beam is not squeezed. However, these results are very promising in view of the generation of quantum correlated polariton modes.