Photon statistics in Jaynes-Cummings model without the rotating-wave approximation

The expectation value of the number operator and the total energy are evaluated in a system of single two-level atom interacting with a single-mode quantized radiation field without the rotating-wave approximation (RWA) using the coherent state propagator for the system. First order corrections are obtained to the RWA results. Certain aspects of photon statistics, e.g. photon anti-bunching are discussed and it is shown that the energy of the atom-field system exhibits periodic collapse and revival alongwith rapid oscillations.