Anomalous Rabi Oscillations in Multilevel Quantum Systems

We show that the excitation probability of a state within a manifold of levels undergoes Rabi oscillations with the frequency determined by the energy difference between the states and not by the pulse area, for sufficiently strong pulses. The population and coherence remains in the two-level subsystem formed by the initial and target state even at Rabi frequencies exceeding the energy difference. The observed dynamics can be useful in nonlinear spectroscopy and quantum state preparation.