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

Dual-channel spectral interferometry is used to measure the vectorial dynam ics of the the four-wave-mixing signal from a GaAs-AlGaAs multiple quantum well when both heavy-and light-hole excitons are excited. The ellipticity, the orientation, and the sense of rotation of the polarization ellipse asso ciated with this emission are observed to oscillate dramatically at the hea vy-hole-light-hole quantum beat frequency, The qualitative nature of the be ating can be described by a simple model based on the density matrix equati ons for two independent three-level systems without the inclusion of many b ody effects; however, these beats are superposed on a polarization that is dominated by many-body effects.