Vacuum fluctuations and moving atoms/detectors: from the Casimir–Polder to the Unruh–Davies–DeWitt–Fulling effect

Abstract

In this note we report on some new results \cite{SHP} on corrections to the Casimir-Polder \cite{caspol} retardation force due to atomic motion and present a preliminary (unpublished) critique on one recently proposed cavity QED detection scheme of Unruh effect \cite{Unr76}. These two well-known effects arise from the interaction between a moving atom or detector with a quantum field under some boundary conditions introduced by a conducting mirror/cavity or dielectric wall. The Casimir-Polder force is a retardation force on the atom due to the dressing of the atomic ground state by the vacuum electromagnetic field in the presence of a conducting mirror or dielectric wall. We have recently provided an improved calculation by treating the mutual influence of the atom and the (constrained) field in a self-consistent way. For an atom moving adiabatically, perpendicular to a mirror, our result finds a coherent retardation correction up to twice the stationary value. Unruh effect refers loosely to the fact that a uniformly accelerated detector feels hot. Two prior schemes have been proposed for the detection of `Unruh radiation', based on charged particles in linear accelerators and storage rings. Here we are interested in a third scheme proposed recently by Scully {\it et al} \cite{Scully03} involving the injection of accelerated atoms into a microwave or optical cavity. We analyze two main factors instrumental to the purported success in this scheme, the cavity factor and the sudden switch-on factor. We conclude that the effects engendered from these factors are unrelated to the Unruh effect.