Quantum kinetics of exciton-folded acoustic phonon in GaAs multiple quantum wells

Oscillation behavior with periods of 0.56 and 0.88 ps has been observed by time-integrated four-wave-mixing measurements in GaAs multiple quantum wells. Temperature and excitation density dependence shows that the oscillations are caused by the quantum kinetic interactions between excitons and phonons. The energies of the phonons correspond exactly to those of the folded acoustic phonons calculated by the Rytov model.