Dynamics of the Jaynes-Cummings and Rabi models: old wine in new bottles

By using a wavepacket approach, this paper reviews the Jaynes-Cummings model with and without the rotating wave approximation ( RWA) in a non-standard way. This gives new insight, not only of the two models themselves, but of the RWA as well. Expressing the models by field quadrature operators, instead of the typically used boson ladder operators, wavepacket simulations are presented. Several known phenomena of these systems, such as collapse-revivals, Rabi oscillation, squeezing and entanglement, are reviewed and explained in this new picture, either in an adiabatic or diabatic frame. The harmonic shape of the potential curves that the wavepackets evolve on and the existence of a level crossing make these results interesting in a broader sense not only for models in quantum optics, but especially in atomic and molecular physics.