Comparison of the biexciton and exciton coherent polarization lifetimes in ZnSe/(Zn,Cd)Se multiple quantum wells

We report the relative coherence lifetimes for the biexciton polarization and the exciton polarization following ultrafast resonant excitation in ZnSe/(Zn,Cd)Se multiple quantum wells. The excitonic and biexcitonic nature of the observed third-order polarization is demonstrated by selection rules and comparison with a theoretical treatment. We show the polarization coherence lifetimes to be related by a factor of two and discuss the origin of this relationship.