177 research outputs found
Numerical Simulation of Radiative Transfer of Electromagnetic Angular Momentum
We present numerical simulations of light emitted by a source and scattered
by surrounding electric dipoles with Zeeman splitting. We calculate the leakage
of electromagnetic angular momentum to infinity.Comment: submitted to Acta Physica Polonica A: Conference Proceedings of 11th
Workshop on Quantum Chaos and Localisation Phenomena, May 202
Radiation of Optical Angular Momentum from a Dipole Source in a Magneto-birefringent Environment
We investigate the radiation of optical angular momentum by a dipole gas
under uniform magnetic field with an unpolarized source at its center.
Conservation of angular momentum implies that the radiation of angular momentum
results in a torque on both the source and the surrounding environment.
Moreover, we study the spin and orbital contributions to the radiated angular
momentum
Superfluidity versus Anderson localization in a dilute Bose gas
We consider the motion of a quasi one dimensional beam of Bose-Einstein
condensed particles in a disordered region of finite extent. Interaction
effects lead to the appearance of two distinct regions of stationary flow. One
is subsonic and corresponds to superfluid motion. The other one is supersonic,
dissipative and shows Anderson localization. We compute analytically the
interaction-dependent localization length. We also explain the disappearance of
the supersonic stationary flow for large disordered samples.Comment: 4 pages, 3 figures, final published versio
Quasi Two-dimensional Transfer of Elastic Waves
A theory for multiple scattering of elastic waves is presented in a random
medium bounded by two ideal free surfaces, whose horizontal size is infinite
and whose transverse size is smaller than the mean free path of the waves. This
geometry is relevant for seismic wave propagation in the Earth crust. We derive
a time-dependent, quasi-2D radiative transfer equation, that describes the
coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and
Lamb waves). Expressions are found that relate the small-scale fluctuations to
the life time of the modes and to their coupling rates. We discuss a diffusion
approximation that simplifies the mathematics of this model significantly, and
which should apply at large lapse times. Finally, coherent backscattering is
studied within the quasi-2D radiative transfer equation for different source
and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.
Mesoscopic Correlation with Polarization of Electromagnetic Waves
Mesoscopic correlations are observed in the polarization of microwave
radiation transmitted through a random waveguide. These measurements, supported
by diagrammatic theory, permit the unambiguous identification of short, long,
and infinite range components in the intensity correlation function, as well as
an additional frequency-independent component.Comment: 4+ RevTex pages, 4 figure
Diffusion and Localization of Cold Atoms in 3D Optical Speckle
In this work we re-formulate and solve the self-consistent theory for
localization to a Bose-Einstein condensate expanding in a 3D optical speckle.
The long-range nature of the fluctuations in the potential energy, treated in
the self-consistent Born approximation, make the scattering strongly velocity
dependent, and its consequences for mobility edge and fraction of localized
atoms have been investigated numerically.Comment: 8 pages, 11 figure
Saturation induced coherence loss in coherent backscattering of light
We use coherent backscattering (CBS) of light by cold Strontium atoms to
study the mutual coherence of light waves in the multiple scattering regime. As
the probe light intensity is increased, the atomic optical transition starts to
be saturated. Nonlinearities and inelastic scattering then occur. In our
experiment, we observe a strongly reduced enhancement factor of the coherent
backscattering cone when the intensity of the probe laser is increased,
indicating a partial loss of coherence in multiple scattering
Observation of coherent backscattering of light by cold atoms
Coherent backscattering (CBS) of light waves by a random medium is a
signature of interference effects in multiple scattering. This effect has been
studied in many systems ranging from white paint to biological tissues.
Recently, we have observed CBS from a sample of laser-cooled atoms, a
scattering medium with interesting new properties. In this paper we discuss
various effects, which have to be taken into account for a quantitative study
of coherent backscattering of light by cold atoms.Comment: 25 pages LaTex2e, 17 figures, submitted to J. Opt. B: Quant. Semicl.
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