Observation of modified radiative properties of cold atoms in vacuum near a dielectric surface

Abstract

We have observed a distance-dependent absorption linewidth of cold 87 Rb atoms close to a dielectric-vacuum interface. This is the first observation of modified radiative properties in vacuum near a dielectric surface. A cloud of cold atoms was created using a magneto-optical trap (MOT) and optical molasses cooling. Evanescent waves (EW) were used to observe the behavior of the atoms near the surface. We observed an increase of the absorption linewidth with up to 25% with respect to the free-space value. Approximately half the broadening can be explained by cavity-quantum electrodynamics (CQED) as an increase of the natural linewidth and inhomogeneous broadening. The remainder we attribute to local Stark shifts near the surface. By varying the characteristic EW length we have observed a distance dependence characteristic for CQED.

Cold-Atom Physics Using Ultrathin Optical Fibers: Light-Induced Dipole Forces and Surface Interactions

“…In particular, this includes the mechanical and spectral effects of the van der Waals (vdW) interaction and a significant enhancement of the spontaneous emission rate of the atoms due to a modification of the vacuum modes by the fiber. An enhanced spontaneous emission of atoms in vacuo coupled to a continuous set of evanescent modes has already been observed in evanescent wave spectroscopy on a plane dielectric surface [11]. In our case, however, the ultra-thin fiber only sustains a single mode at the atomic wavelength.…”

Atomic decay near a quantized medium of absorbing scatterers

“…Interference fringes in emission processes due to reflection at an ideal mirror have been observed experimentally [29]. The modification of radiative properties near a dielectric medium has been determined experimentally a few years ago as well [22].…”

Anticrossing-mediated entanglement of adsorbed polar molecules

“…If the molecules are placed close to a dielectric surface, the lifetime τ c is modified to be lower than τ c . In analogy to the atomic systems [34][35][36], the surface-induced effect is related to the refractive index. For silica, the ratio τ c /τ g is obtained at approximately 10 10 .…”