Abstract
The interaction of a single atom with a single quantized field mode is one of the simplest quantum optical models of resonance, yet exhibits a wide variety of non-trivial fundamental features which depend for their existence on field quantization. We discuss such problems with special emphasis on reversible spontaneous emission and one-photon Rabi oscillations, photon statistical collapses and revivals of coherent evolution, and the existence of phase-dependent squeezed quantum noise.