DYNAMICS OF A 3-LEVEL ATOM IN A 2-MODE SQUEEZED VACUUM

In this paper we study the dynamics of a three-level atom interacting with a two-mode squeezed vacuum, a highly correlated state in which each mode contains the same number of quanta yet exhibits a thermal photon distribution. Under exact resonance, the Rabi oscillations exhibit an irregular behavior reminiscent of those in the thermal-state Jaynes-Cummings model. If the individual field modes are sufficiently detuned from the intermediate atomic level, the Rabi oscillations become quasiperiodic. The three-level system in this case reduces to an effective two-level system in which two-photon processes dominate. The times of revivals of the Rabi oscillations in this limit depend only on the atom-field coupling constants and the detuning. For comparison, we present a parallel study of the case in which the initial field is prepared in an uncorrelated two-mode state, such as a two-mode thermal state or a two-mode coherent state. Under the full resonance condition, the former leads to an irregular evolution of the Rabi oscillations, while the latter leads to the usual collapse and revival phenomena. If the individual modes are sufficiently detuned from the intermediate atomic level, we observe the same quasiperiodicity of the Rabi oscillations as in the case of the two-mode squeezed vacuum but with a doubling of revival times (for equal atom-field coupling constants). Whereas the two-mode squeezed vacuum and the two-mode thermal-state transition dynamics lead to correlation between the field modes, the two-mode coherent state leads to anticorrelation (when sufficiently detuned from the intermediate atomic level).