A.B. Klimov, J.L. Romero and C. Saavedra
PHYSICAL REVIEW A 64, 6 (2001)
We consider the interaction of an arbitrary quantum system with a single field cavity mode without the Rotating-Wave Approximation (RWA). The cavity mode is damped by coupling to a reservoir at zero temperature. We show that the system evolution is governed by an effective Linblad-type master equation with nonzero temperature terms leading to a nonzero stationary state, even without an external driven field. The system evolution under the RWA is also considered. Two particular cases of atom-field and field-field interaction are discussed.