NUMERICAL-ANALYSIS OF NON-MARKOVIAN EFFECTS IN CHARGE-CARRIER SCATTERING - ONE-TIME VERSUS 2-TIME KINETIC-EQUATIONS

The non-Markovian carrier-carrier scattering dynamics in a dense elect ron gas is investigated. Within the framework of quantum kinetic equat ions in the second Born approximation we study the relevance of retard ation (memory) effects, energy broadening and correlation build-up for femtosecond relaxation processes. Furthermore, the important issue of total energy conservation, within various well-established approximat ion schemes, is analysed. The most important non-Markovian effect is s hown to be the broadening of the energy delta function leading to an i ncrease of kinetic energy with time. Our numerical analysis includes b oth the single-time kinetic equation and the full two-time Kadanoff-Ba ym equations. Our results are expected to correctly reproduce qualitat ive features of non-Markovian dynamics in plasmas, fluids, nuclear mat ter and in the intraband relaxation of semiconductors. The comparison of the exact solutions for different approximations allows suggestions for simplifications that make this kind of calculation and their exte nsion, especially to realistic semiconductor situations, more feasible .