Influence of two-pair continuum correlations following resonant excitationof excitons

The memory structure induced by coherent transitions to the exciton-exciton scattering continum is shown to have significant influence on spectrally r esolved four-wave-mixing signals even under selective excitation of Is exci tons. Comparisons between experiments and calculations that account nonpert urbatively for these quantum kinetic Coulomb correlations demonstrate large compensations between mean-field contributions and transitions to the two- pair continuum. Experiments with different polarizations of the laser pulse s show that two-pair continuum correlations are responsible for delay-time dependent shifts of the excitonic emission as well as for substantial defor mations of the line shape.