Atomic, Molecular, and Optical Physics Seminar
Electromagnetic Wave Dynamics in Ultracold, High-Density Rb Vapor
Department of Physics
Old Dominion University
Recent experiments and theoretical results on Anderson localization of light in condensed samples show that diffusive transport is strongly suppressed and that a regime of anomalous diffusion develops dynamically. Proximity of the light localization threshold can be detected through time evolution of either forward or diffusely scattered light. In this presentation I will first discuss light scattering in ultracold atomic rubidium samples in the weak localization regime. In this lower-density limit, far from the Anderson localization threshold, light transport in a finite sample can be thought of as consisting of individual time-reversed chains of scattering and propagation steps. Results on time-dependent scattering, including the spectral and polarization variations, will be discussed. We have recently done experiments at much higher densities, in the vicinity of the localization transition. Measurements are made of the intensity and time-dependence of light scattering in the spectral vicinity of the F=1 → F'=0 optical transition. For these ultracold atomic 87Rb samples, formed in an optical dipole trap, the density is ~ 1014atoms/cm3. At this density, the Ioffe-Regel criterion kl ~ 0.8, indicating that localization, effects should be evident. Here k is the wave vector of the light in the medium, and l is the mean free path for light scattering in the sample. Theoretical results on spectral variations of the total scattering cross section in the strong localization regime will also be presented.
This research is supported by the National Science Foundation.
Monday, February 26, 2007
Gant Science Complex