Full inversion of a two-level atom with a single-photon pulse in one-dimensional geometries

We analyze a system comprising a one-dimensional single-mode waveguide (a) coupled directly to a two-level atom (b) side-coupled to a cavity containing a two-level atom and show that in both cases it is possible to invert the atom with a single-photon pulse. In contrast to the semiclassical pi pulse, the inverting single-photon pulse is unique.