Transcript Fall 2005 Physics Seminar Physics Mesoscopic Electromagnetic Dynamics in Atomic Gases Mark Havey Physics Department Old Dominion University Abstract: Light scattering has a long and interesting history.

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Fall 2005 Physics Seminar
Physics
Mesoscopic Electromagnetic
Dynamics in Atomic Gases
Mark Havey
Physics Department
Old Dominion University
Abstract: Light scattering has a long and interesting history in science, with some of
the earliest written records on natural philosophy concerned with the nature of vision and
light itself. The quantitative study of light, which began in earnest in the 18th century,
culminated in the classic paper by Lord Rayleigh on the well-known light scattering
process that bears his name. Although modern descriptions of the quantized
electromagnetic field go far beyond those early efforts, it may be surprising that there are
remarkable optical effects being discovered today. Some of these are associated with
light scattering in common materials such as milk, white paint, turbid liquids, or biological
samples. In the past, propagation of light in diffusive media was thought to be not very
interesting, and in reality something to be avoided. However, in the past two decades, a
wide range of remarkable phenomena associated with coherent radiative transport has
been observed in solids and liquids. First detailed observations of coherent effects in light
scattering were made in 1985 of coherent backscattering, an effect in which light incident
on a sample follows reciprocal (time reversed) paths through the material. Identical phase
accumulation for these paths results in constructive interference for light scattered into a
narrow cone in the backward direction. In this presentation, the coherent backscattering
effect, and more general mesoscopic phenomena occurring in multiple scattering media
will be described. These include radiation transport and correlation effects appearing in
the weak localization regime. The strong scattering limit in an atomic gas, when light
transport is suppressed by the disordered spatial distribution of atoms, will also be
discussed. Such strong localization is a type of phase transition and is closely related to
an idealized Anderson localization transition driven by disorder.
Wed. Nov. 9th