Cavity quantum electrodynamics inside a hollow spherical cavity

We present a general formalism for studying the cavity quantum electrodynamics for an atom or a radiating dipole inside a hollow spherical cavity. The atomic-energy-level shifts and the modified dipolar decay rates are calculated in specific cases. In particular, the energy shifts for an atom located at the center of an empty sphere (radius a) vary as 1/${\mathit{a}}^4$ for large ka and 1/${\mathit{a}}^2$ for small ka, where k is the wave number. We attribute these variations to the retarded Casimir-Polder interaction and the state-independent vacuum-field contribution, respectively. © 1996 The American Physical Society.