Quantum electrodynamics based on self-energy: Spontaneous emission in cavities

We extend a previously developed formulation of QED based on self-energy to include the effect of perfectly conducting boundaries on spontaneous emission. The method is quite general and applicable to any quantum system and many boundary geometries. In particular, we compute the spontaneous emission rate of an atom near a conducting plate, inside a spherical cavity, and between parallel plates. We give general formulas and predict both enhanced and inhibited rates, in agreement with recent experiments.