Memory effects in the momentum orientation relaxation of optically excited plasmas in semiconductors

In the study of memory effects in the momentum orientation relaxation, the theoretical basis of analysis are the equations of motion for the the full two-time one-particle Green's function g < (k^→, t₁, t₂) within the screened Hartree-Fock approximation. This Green's function reduces to the distribution function of the charge carriers as function of momentum k and time t in the equal time limit: f(k^→, t) = -iℏg < (qq, t, t). The numerical solution incorporates full correlation effects because it is based on an time integration in the two-dimensional t₁ - t₂ plane. Of course, one can apply certain additional approximations such as the Markov approximation to reduce the equation of motion to the conventional Boltzmann equation. The comparison of the results with and without such additional approximations yields important information about charge-carrier correlation contributions, memory effects, and nonkinetic energy preserving processes.