Rabi flopping without resonance

A three-level atom interacting with laser fields of different frequencies out of resonance is studied. The corresponding theory of dressed states is applied and extended beyond the leading order to obtain the higher-order corrections. These higher-order corrections can be computed by a dual Dyson series. Rather than to apply perturbation theory, the equations for the probability amplitudes of the transformed Hamiltonian in the dual interaction picture are considered. This gives us the opportunity to study the resonance properties of the quantum dynamics of the three-level atom being driven out of resonance by the external laser fields. In this way, by different resonance conditions due both to the detunings and the couplings, one gets Rabi flopping without resonance of the external fields and the atom levels, with also the Rabi frequency originating both from the detunings and the couplings.