A Quantum Electrodynamic Investigation of the Jaynes-Crisp-Stroud Approach to Spontaneous Emission

Abstract

Motivated by the work of Jaynes and co-workers, [1] the old problem of atomic level shifts and widths has recently begun to be re-examined. While QED is a highly successful theory (indeed the only workable field theory we have), it is still beset with self-energy infinities ultimately associated with the point-like nature of the electron. These are removed from the public view by the process of renormalization, in the hope that eventually some high frequency cut-off will be found to make the renormalization constants finite: such modifications proposed usually imply a radius to the electron. In the usual approach to QED, perturbation theory is used. Jaynes, prompted by the great progress made in theory and experiments on atoms interacting with electromagnetic fields, has re-investigated the problem of spontaneous emission by solving the relevant semi-classical equations of motion for the interacting field-atom system directly. An interesting product of such an approach (other than the novel time-dependence) is the non-appearance of divergences: the finite size of the atomic charge distribution removes the point like singularity when retardation is taken into account.

Research partially supported by the U.S. Army Research Office (Durham) and the U.S. Atomic Energy Commission