1 Rabi flopping and Schrödinger cat states

A two-level atom interacting with a single radiation mode is considered, without the rotating-wave approximation, in the strong coupling regime. It is shown that, in agreement with the recent results on Rabi flopping in a Josephson junction (Y. Nakamura, Yu. A. Pashkin and J. S. Tsai, to appear in Phys. Rev. Lett.), the Rabi frequency is indeed proportional to first kind integer order Bessel functions in the limit of a large number of photons and the dressed states are Schrödinger cat states. To approach this problem analytically use is made of the dual Dyson series and the rotating-wave approximation. PACS: 42.50.Ct, 42.50.Hz, 74.50.+r, 85.25.Cp Typeset using REVTEX