Radiative level shifts of an accelerated hydrogen atom and the Unruh effect in quantum electrodynamics

Abstract

The contribution of vacuum fluctuations and the radiation reaction to the energy-level shifts of a hydrogen atom, moving with uniform acceleration and interacting with the electromagnetic field, is considered. It is found that the reaction field contribution is not affected by the acceleration, whereas the vacuum fluctuations' contribution depends on the acceleration. The differences with previous results for an accelerated two-level atom interacting with a scalar field are discussed in detail; in particular, it is shown that the effect of electromagnetic vacuum fluctuations on atomic level shifts, contrarily to the scalar field case, is not totally equivalent to that of a thermal field. It is argued that this lack of equivalence should be observable.