S. Savasta et R. Girlanda, Signatures of the electromagnetic field quantization in the nonlinear optical response of excitons, J PHYS-COND, 11(31), 1999, pp. 6045-6059
We present a fully quantum mechanical theory for an interacting system of p
hotons and Coulomb correlated electrons and holes in a semiconductor, using
a pertubation series in the exciting laser field. The theory provides micr
oscopic descriptions of nonlinear optical processes in semiconductors relat
ed to the electromagnetic field quantization. As an application of the theo
ry we show that it is possible to transfer the exciton-exciton Coulomb corr
elation to photons, thus producing pairs of near-gap photons with a high de
gree of quantum entanglement. The photon pairs emerge from the spontaneous
optical decay of biexcitons into two polaritons. The pair intensity correla
tions, calculated in the low density limit for a CuCl slab and for semicond
uctor microcavities, exhibit quantum features which can be observed by coin
cidence detection.