COULOMB QUANTUM KINETICS AND OPTICAL DEPHASING ON THE FEMTOSECOND TIME-SCALE

Quantum kinetic equations with memory are formulated and solved for th e femtosecond Coulomb kinetics of an optically excited electron-hole p lasma. In a time interval smaller than the inverse plasma frequency sc reening and energy conservation are still absent. The resulting decay of the optical interband polarization is shown to be nonexponential an d is in qualitative agreement with the results of the quasiclassical t heory of Gurevich et al.