Quantum kinetic exciton–LO-phonon interaction in CdSe

Oscillations with a period of $\sim 150$ fs are observed in the four-wave mixing (FWM) signal of bulk CdSe and interpreted in terms of non-Markovian exciton–LO-phonon scattering. The experiments show evidence of phonon quantum kinetics in semiconductors of strong polar coupling strength and high exciton binding energy. By comparison of the spectral and temporal response of the FWM signal in bulk CdSe and CdSe quantum dots, we demonstrate the influence of continuum states on the interference of electron-hole pair polarizations coupled via an LO phonon.