A comparative study of hyperbunching in the fluorescence from a bichromatically driven atom

Recently, Miranowicz et al compared three different definitions of antibunc hing in non-stationary fields and found that they are by no means equivalen t. In particular, they may lead to contradictory predictions of the photon antibunching. We consider another violation of the Cauchy-Schwarz inequalit y in non-classical and non-stationary fields which we term as hyperbunching . Similarly, this leads to three different definitions of hyperbunching in non-stationary fields which, again, are by no means equivalent and may lead to contradictory predictions of this phenomenon. We analyse these differen t concepts of anti- and hyperbunching in the non-stationary resonance fluor escence from a bichromatically driven two-level atom.