arXiv:1009.2344 · Physical Review A
QED with a spherical mirror
Gabriel Hetet, L. Slodička, A. Glätzle, Markus Hennrich, R. Blatt
Abstract
We investigate the quantum electrodynamic (QED) properties of an atomic electron close to the focus of a spherical mirror. We first show that the spontaneous emission and excited-state level shift of the atom can be fully suppressed with mirror-atom distances of many wavelengths. A three-dimensional theory predicts that the spectral density of vacuum fluctuations can indeed vanish within a volume ${\ensuremath{\lambda}}^{3}$ around the atom, with the use of a far-distant mirror covering only half of the atomic emission solid angle. The modification of these QED atomic properties is also computed as a function of the mirror size, and large effects are found for only moderate numerical apertures. We also evaluate the long-distance ground-state energy shift (Casimir-Polder shift) and find that it scales as $(\ensuremath{\lambda}/R){}^{2}$ at the focus of a hemispherical mirror of radius $R$, as opposed to the well-known $(\ensuremath{\lambda}/R){}^{4}$ scaling law for an atom at a distance $R$ from an infinite plane mirror. Our results are relevant for investigations of QED effects as well as free-space coupling to single atoms using high-numerical-aperture lenses.