Influence of a virtual photon field on the statistic properties of photonsin a system of two-mode squeezed vaccum field interacting with atoms

The statistic properties of photons in a system of two-mode squeezed vacuum field interacting with a two-level atom are studied without the rotating-w ave approximation by means of quantum theory, and the influence of the virt ual-photon process on the statistic properties of photons is discussed emph atically. The results obtained using a numerical method indicate that the i nfluence of the virtual-photon process on the statistic properties of photo ns qives rise to quantum chaos, that is related to the initial state parame ters of the system.