QUANTUM EFFECTS IN 2-LEVEL ATOM SQUEEZED VACUUM INTERACTIONS FOR LARGE PHASE DIFFERENCES

Many unusual features in the interaction between driven two-level atom atoms and the squeezed vacuum have been reported recently. These effe cts are usually most pronounced when the phase difference Phi between the driving field phase and the squeezed vacuum phase is small, and te nd to disappear as Phi --> pi. In this paper, we show that a range of unusual features arise when Phi is close to pi. In the present treatme nt, it is essential not to make the secular approximation. The effects described include population trapping of a dressed state, disappearan ce of peaks in the resonance fluorescence spectrum, amplification of a probe beam and a large peak in the coherently scattered amplitude. Th ese features disappear when the two-photon correlations in the squeeze d vacuum are reduced to the classical level, and their existence must be attributed to the quantum nature of the squeezed vacuum. (C) 1998 E lsevier Science B.V.