  Through a quantitative analysis of an atomic transition driven strongly by
quantized electromagnetic fields of various quantum states, we explore the role
of quantum fluctuations on the behavior of the system. The emphasis is on
fields with super-Poissonian statistics manifested in photon bunching, with the
case of squeezed vacuum radiation serving as a prototype of superbuching. When
combined with non-linearly coupling of the resonant states, bunching and
superbunching lead to counter-intuitive behavior. The connection to recent
progress in squeezed vacuum sources and the opportunity for experimental
investigation, as well as challenging open theoretical problems are also
outlined.
