Heavy-hole and light-hole quantum beats in the polarization stateof coherent emission from quantum wells

摘要

Dual-channel spectral interferometry is used to measure thenvectorial dynamics of the the four-wave-mixing signal from a GaAs-AlGaAsnmultiple quantum well when both heavy-and light-hole excitons arenexcited. The ellipticity, the orientation, and the sense of rotation ofnthe polarization ellipse associated with this emission are observed tonoscillate dramatically at the heavy-hole-light-hole quantum beatnfrequency. The qualitative nature of the beating can be described by ansimple model based on the density matrix equations for two independentnthree-level systems without the inclusion of many body effects; however,nthese beats are superposed on a polarization that is dominated bynmany-body effects