591 research outputs found
Coherent Backscattering with Nonlinear Atomic Scatterers
We study coherent backscattering of a quasi-monochromatic laser by a dilute
gas of cold two-level atoms. We consider the perturbative regime of weak
intensities, where nonlinear effects arise from {\em inelastic} two-photon
scattering processes. Here, coherent backscattering can be formed by
interference between {\em three} different scattering amplitudes. Consequently,
if elastically scattered photons are filtered out from the photodetection
signal by means of suitable frequency-selective detection, we find the
nonlinear backscattering enhancement factor to exceed the linear barrier two.Comment: 4 pages, 3 figure
Scattering laser light on cold atoms: multiple scattering signals from single-atom responses
We deduce the coherent backscattering signal from two distant laser-driven
atoms using single-atom equations. In contrast to the standard master equation
treatment, this new approach is suitable for the generalization to a large
number of atomic scatterers.Comment: 4 pages, 2 figure
Coherent Backscattering of Light with Nonlinear Atomic Scatterers
We study coherent backscattering of a monochromatic laser by a dilute gas of
cold two-level atoms in the weakly nonlinear regime. The nonlinear response of
the atoms results in a modification of both the average field propagation
(nonlinear refractive index) and the scattering events. Using a perturbative
approach, the nonlinear effects arise from inelastic two-photon scattering
processes. We present a detailed diagrammatic derivation of the elastic and
inelastic components of the backscattering signal both for scalar and vectorial
photons. Especially, we show that the coherent backscattering phenomenon
originates in some cases from the interference between three different
scattering amplitudes. This is in marked contrast with the linear regime where
it is due to the interference between two different scattering amplitudes. In
particular we show that, if elastically scattered photons are filtered out from
the photo-detection signal, the nonlinear backscattering enhancement factor
exceeds the linear barrier two, consistently with a three-amplitude
interference effect.Comment: 18 pages, 13 figures, submitted to Phys. Rev.
Inelastic Multiple Scattering of Interacting Bosons in Weak Random Potentials
We develop a diagrammatic scattering theory for interacting bosons in a
three-dimensional, weakly disordered potential. We show how collisional energy
transfer between the bosons induces the thermalization of the inelastic
single-particle current which, after only few collision events, dominates over
the elastic contribution described by the Gross-Pitaevskii ansatz.Comment: 5 pages, 3 figures, very close to published versio
Number-conserving master equation theory for a dilute Bose-Einstein condensate
We describe the transition of weakly interacting atoms into a
Bose-Einstein condensate within a number-conserving quantum master equation
theory. Based on the separation of time scales for condensate formation and
non-condensate thermalization, we derive a master equation for the condensate
subsystem in the presence of the non-condensate environment under the inclusion
of all two body interaction processes. We numerically monitor the condensate
particle number distribution during condensate formation, and derive a
condition under which the unique equilibrium steady state of a dilute, weakly
interacting Bose-Einstein condensate is given by a Gibbs-Boltzmann thermal
state of non-interacting atoms
A Narrow QRS Complex Tachycardia:
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73616/1/j.1540-8167.1999.tb00200.x.pd
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