QED level shifts of atoms between two mirrors

Abstract

We calculate the QED energy-level shifts of an atom between two perfectly conducting mirrors in perturbation theory. We separate the contributions of vacuum fluctuation and self-radiation reaction to the shifts between two mirrors. This provides unambiguous assignment of each effect on the cavity-induced shifts, and allows reinterpretation of previously derived results. In particular, we are able to identify the Casimir interaction as a pure effect of vacuum fluctuation.