Spin flip of excitons in GaAs quantum wells

We report measurements of the rates of conversion from J=2 excitons to J=1 excitons, as well as conversion from right-handed J=1 excitons to left-handed J=1 excitons, and measurement of the intrinsic radiative lifetime of J=1 excitons, in very-high-quality GaAs quantum wells. Since the experiments are performed at very low temperature and with resonant excitation, the effects of energy relaxation are absent.