Squeezing and rabi oscillations in the Dicke model within and without rotating-wave approximation

The Dicke model is investigated within and without rotating-wave approximation in the case of a lossless resonant cavity. Numerical results for the time evolution of the atomic population inversion, dipole moment and atomic and field squeezing parameters for an initial field are presented for different numbers of atoms. The significant influence of the counter-rotating terms on the squeezing and collapse (revival) phenomena is pointed out.