Anomalously Fast Decay of the LH-HH Exciton Raman Coherence
C N. Borca, A G. VanEngen Spivey, Steven T. Cundiff
We perform a three-pulse transient four-wave-mixing experiment on a weakly disordered GaAs/AlGaAs multiple quantum well. This allows us to measure both the decay of the Raman coherence between the heave-hole and light -hole excitons in a semiconductor multiple quantum well and the decay of the respective optical coherences. We observe that the decay rate of the Raman coherence can be greater than the sum of decay rates of the optical coherences. This cannot happen within a Markovian approximation for the scattering processes, as verified by simulations. The simulations show that such behavior can occur only in the presence of anti-correlated scattering processes in a non-Markovian regime.