We report direct, time-resolved observations of single-photon superradiance in a highly extended, elliptical sample of cold 87 Rb atoms. The observed rapid decay rate is accompanied by its counterpart, the cooperative Lamb shift. The rate of the strongly directional decay, and the associated shift, scale linearly with the number of atoms, demonstrating the collective nature of the observed quantities.

We demonstrate that a cold, dense sample of Rb87 atoms can exhibit a micron-scale lensing effect, much like that associated with a macroscopically sized lens. The experiment is carried out in the fashion of traditional z-scan measurements but in much weaker fields and where close attention is paid to the detuning dependence of the transmitted light. The results are interpreted using numerical simulations and by modeling the sample as a thin lens with a spherical focal length.

We report investigation of near-resonance light scattering from a cold and dense atomic gas of 87 Rb atoms. Measurements are made for probe frequencies tuned near the F = 2 → F ′ = 3 nearly closed hyperfine transition, with particular attention paid to the dependence of the scattered light intensity on detuning from resonance, the number of atoms in the sample, and atomic sample size. We find that, over a wide range of experimental variables, the optical depth of the atomic sample serves as an effective single scaling parameter which describes well all the experimental data.

A brief perspective on light scattering in dense and cold atomic rubidium is presented. We particularly focus on the influence of auxiliary applied fields on the system response to a weak and nearly resonant probe field. Auxiliary fields can strongly disturb light propagation; in addition to the steady state case, dynamically interesting effects appear clearly in both the time domain, and in the optical polarization dependence of the processes. Following a general introduction, two examples of features found in such studies are presented. These include nonlinear optical effects in (a) comparative studies of forward- and fluorescence-configuration scattering under combined excitation of a control and probe field, and (b) manipulation of the spatial structure of the optical response due to a light shifting strong applied field

The phenomenon of electronic wave localization through disorder was introduced by Anderson in 1958 in the context of electron transport in solids. It remains an important area of fundamental and applied research. Localization of all wave phenomena, including light, is thought to exist in a restricted one dimensional geometry. We present here a series of experiments which illustrate, using a simple experimental arrangement and approach, localization of light in a quasi one dimensional physical system. In the experiments, reflected and transmitted light from a stack of glass slides of varying thickness reveals an Ohm's Law type behavior for small thicknesses, and evolution to exponential decay of the transmitted power for thicker slide stacks. Light absorption is negligible in our realization of the experiment. For larger stacks of slides, weak departure from a one dimensional behavior is also observed. The experiment and analysis of the results, then showing many of the essential features of wave localization, is relatively straightforward, economical, and suitable for laboratory experiments at an undergraduate level.