  We present a quantum kinetic approach for the time-resolved description of
many-body effects in photoionization processes in atoms. The method is based on
the non-equilibrium Green functions formalism and solves the
Keldysh/Kadanoff-Baym equations in second Born approximation. An approximation
scheme is introduced and discussed, which provides a complete single-particle
description of the continuum, while the atom is treated fully correlated.
