Quantum Kinetic Equations: Correlation Dynamics and Selfenergy

The derivation of non—Markovian quantum kinetic equations is reconsidered in the framework of density operators. Conventional derivations use for the decoupling of the BBGKY‐hierarchy the assumption of vanishing three—particle correlations g123 = 0. This yields non—Markovian kinetic equations with infinite memory depth. We discuss a different closure relation to the hierarchy, which overcomes this difficulty without assumptions on weakening of initial correlations and in fact corresponds to the inclusion of selfenergy effects (beyond Hartree—Fock).