  In this contribution we investigate quantum electrodynamical many-mode
aspects by exploring the simplest possible situation in this context, namely
the interaction of a single atom, modeled by a simple two-level system, with
many-mode one-photon quantum states of the electromagnetic field. In
particular, we concentrate on the question how the engineering of
electromagnetic field modes influences the atom-field interaction. An
interesting problem in this context is the engineering of ideal one-photon
multi-mode quantum states which may excite a single atom perfectly [M.
Stobi\'nska, G. Alber, and G. Leuchs, EPL {\bf 86}, 14007 (2009)]. For purposes
of quantum information processing such one-photon multi-mode states are
particularly well suited for transmitting quantum information and for storing
it in a material memory again.
