Phenomenological-operator approach to dissipation in cavity quantum electrodynamics - art. no. 033815

We present a phenomenological-operator approach to describe energy dissipat ion in cavity QED phenomena. This approach, developed for an absolute-zero and a thermal environment, considerably simplifies the introduction of the inevitable errors due to the environmental degrees of freedom when describi ng processes involving dispersive atom-field interactions. The main result in the present work consists in furnishing a straightforward technique to e stimate the fidelity resulting from dispersive atom-field interactions, pre cluding the necessity of performing the usually extensive ab initio calcula tions. Furthermore, we expect that the present work can help us account for dissipation in resonant atom-field interactions and even help us achieve a general phenomenological approach to estimate the effects of dissipation i n whichever system. To illustrate the universal applicability of the presen t technique, we calculate the fidelity of a mesoscopic quantum superpositio n state engineered in a lossy cavity, considering also the excited-state sp ontaneous decay of the required atom. For the case of a stable atomic excit ed state, the fidelity computed here is in agreement with a recently announ ced exact calculation.