Photon Scattering by the Statistical Atom.

M. S. Kim

Igor B. Mekhov, Christoph Maschler, Helmut Ritsch

We study off-resonant collective light scattering from ultracold atoms trapped in an optical lattice. Scattering from different atomic quantum states creates different quantum states of the scattered light, which can be distinguished by measurements of the spatial intensity distribution, quadrature variances, photon statistics, or spectral measurements. In particular, angle-resolved intensity measurements reflect global statistics of atoms (total number of radiating atoms) as well as local statistical quantities (single-site statistics even without optical access to a single site) and pair correlations between different sites. As a striking example we consider scattering from transversally illuminated atoms into an optical cavity mode. For the Mott-insulator state, similar to classical diffraction, the number of photons scattered into a cavity is zero due to destructive interference, while for the superfluid state it is nonzero and proportional to the number of atoms. Moreover, we demonstrate that light scattering into a standing-wave cavity has a nontrivial angle dependence, including the appearance of narrow features at angles, where classical diffraction predicts zero. The measurement procedure corresponds to the quantum nondemolition measurement of various atomic variables by observing light.

Jan Pefina

R. M. Evans

A laser spectroscopy system and the equipment needed for resonance-fluorescence studies with the photon-burst method in an extended interaction region were developed. To accommodate the long, variable transit times of thermal atoms across this extended region a resettable coincidence counter was used;The photon statistics of light scattered from the three-level 5535 A transition in barium were investigated. These statistics agreed well with theory developed in conjunction with this work. An atomic branching ratio of 375 (+OR-) 30 was obtained from the photon number distributions, establishing a new method for determining this quantity. The affect of radiation pressure upon the photon-burst lineshapes was observed. Because of the large number of photons scattered high sensitivity was obtained, allowing measurements with fluxes of less than one atom/sec. The results of this work are important for the study of the hyperfine structure of atoms with short-lived nuclei and in searches for long-lived but exotic nuclei.

N. A. Enaki, Marina Ţurcan

This paper is devoted to the study of the cooperative two-photon scattering processes between two resonator modes stimulated by an excited atomic beam. It has been proved that these collective scattering phenomena between the Stokes and anti-Stokes resonator modes are taking place due to the energy transfer between these fields. The statistical properties of the Stokes and anti-Stokes photons have been described using the photon correlation functions. The numerical solution of this equation describes the statistical transformation of n-Stokes photons into anti-Stokes photons.

K. T. Hecht