  Time-dependent nonequilibrium Green's functions (TDNEGF) are shown to provide
a flexible, effective tool for the description of quantum mechanical single
particle scattering on a spatially localized, time-dependent potential.
Focusing on numerical methods, arbitrary space and time dependence of the
potential can be treated, provided it is zero before an initial time instant.
In this case, appropriate version of the Dyson and Keldysh equations lead to a
transparent description with clear physical interpretation. The interaction of
a short laser pulse and an electron propagating initially in free space is
discussed as an example.
