Squeezed-vacuum effects in the quasienergy structure of atoms in a laser field

摘要

A theory is developed of nonlinear optical processes involving isolated atomic systems in a strong external field and in a squeezed vacuum. The theory is based on transitions between quasienergy states of the system considered. For three systems—a two-level atom in a monochromatic field and in a bichromatic field, and a three-level atom under conditions of two-photon excitation—quantum phase-dependent effects are found in the transition probabilities between quasienergy states under the influence of the squeezed-vacuum field. It is shown that for certain parameters of the fields, these probabilities can be strongly suppressed. This circumstance is also manifested in the stationary interaction regime in our calculations of the resonance fluorescence spectra and in the populations of the atomic levels. It is shown that squeezed-vacuum effects lead to anomalous behavior of the atomic populations and to the possibility of their complete inversion for a three-level atom.