Effect of collision dephasing on atomic evolutions in a high-Qcavity

The decoherence mechanism of a single atom inside a high-Q cavity is studied, and the results are compared with experimental observations reported by M. Brune et al. [Phys. Rev. Lett. 76, 1800 (1996)]. Collision dephasing and cavity leakage are considered as the major sources giving rise to the decoherence effect. In particular, we show that the experimental data can be fitted very well by assuming suitable values of the collision Stark shifts and dark count rate in the detector.