Third-order exciton-correlation and nonlinear cavity-polariton effects in semiconductor microcavities - art. no. 045316

We present a microscopic theory of the coherent third-order (chi ((3))) opt ical response of semiconductor quantum well microcavities, specialized to t he four-wave-mixing configuration in the spectral vicinity of the lowest ex citon frequency. The theory is that of a quantum-mechanical many-electron s ystem dipole coupled to a classical radiation field. The many-electron dyna mics is treated within the dynamics-controlled-truncation formalism restric ted to the Is-exciton subspace. Within this limitation, all Coulomb correla tion effects are included, resulting in an effective theory of (virtual) ex citon-polariton scattering. Good quantitative agreement of the theory is ob tained in comparison to the experiments reported by Gonokami et al., Phys. Rev. Lett. 79, 1341 (1997). This comparison reveals the signatures of both the bound biexciton and the exciton-exciton scattering (continuum) correlat ions. Furthermore. a proper calculation of the scattering correlations is s hown to be important; each of two common approximations, the Markov and the second Born, results in clear discrepancies from the data.