Interaction between two-level atoms and a squeezed vacuum in a cavity: Effect on the mean photon number

The interaction between a squeezed vacuum and a two-level atom coupled to a cavity mode is studied via its influence on the intracavity photon number, the simplest measurable quantity. When the system is driven by a coherent field a remarkable sensitivity to the relative phase between the driving field and the squeezed vacuum appears. The effect is very sensible to the excess of two-photon correlation between a squeezed vacuum and a maximally correlated classical field. The possibility of an experimental demonstration of the effect is established by means of numerical calculations corresponding to a slight modification of an experiment previously reported in the literature.