Wed' Nov' 9th

1
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