The resonant coupling between cesium Rydberg atoms and dielectric surfaces and cavity QED experiments with the blackbody field

H. Failache, Solomon M. Saltiel, M. Fichet +3 more

M. Tada, Yasuaki Kishimoto, K. Kominato +7 more

Edward A. Hinds, K. S. Lai, M. Schnell

Over the past ten years, our group has investigated the effects of confinement on atoms inside metallic micron–sized cavities in order to elucidate some basic phenomena in the field of cavity quantum electrodynamics (QED). The first of these was the inhibition of spontaneous emission from an atom inside a cavity. This was followed by a laser spectroscopic measurement of the van der Waals interaction between a single Rydberg atom and a gold cavity, which showed that a simple electrostatic model of the atom–cavity interaction is correct when the cavity is small enough. More recently, the retarded Casimir–Polder force was measured between a ground state sodium atom and a large cavity, demonstrating that the van der Waals potential fails at long enough range and that the vacuum fluctuations of the field then have an important role in the interaction of the atom with the cavity. Our group is now pushing forward these investigations to study cavities whose walls have losses and dispersion, where the theory of cavity QED is significantly more complicated. With real surfaces, we have to deal with the complex dielectric response ε(ω) of the material, which exhibits frequency–dependent absorption and dispersion. One particularly interesting case is when a downward transition in the atom is resonant with an excitation of the cavity walls. This opens a new branch for the atomic decay: as an alternative to creating a photon within the space surrounded by the cavity walls the atomic decay can now create an electromagnetic excitation of the walls themselves. Another novel feature of our experiments is that the Bohr frequencies of the atom are close to the kT/h, where T is room temperature. We therefore expect to be able to measure effects associated with QED at finite temperature; in other words, to study how the blackbody radiation affects our experiments. By conducting experiments with real surfaces, we hope to elucidate and perhaps simplify the theoretical models used to describe these systems.

P.R. Koch, H. Hieronymus, Anthony F. J. van Raan +1 more

Daniel Kleppner

H. Failache, A. Fischer, Solomon M. Saltiel +4 more

Summary form only given. The topic of quantum cavity electrodynamics is to describe the coupling between the fluctuations of an atomic system and the vacuum e.m. field, when special boundary conditions are imposed by a cavity to the vacuum field. A realistic description of these boundary conditions is hence of crucial importance. For such a purpose, the unavoidable dispersive spectral properties of any material cavity cannot be ignored when dealing with (temporal) fluctuations. For these reasons, we have embarked on an (experimental) analysis of the resonant long-range coupling between atomic excitation and the surface modes of a cavity (most often restricted to a simple wall, i.e. a flat open cavity). In our present investigations, we are concerned with the exploration of the dissipative counterpart of the resonant atom-surface van der Waals coupling.