3,514 research outputs found
Radiation 'damping' in atomic photonic crystals
The force exerted on a material by an incident beam of light is dependent
upon the material's velocity in the laboratory frame of reference. This
velocity dependence is known to be diffcult to measure, as it is proportional
to the incident optical power multiplied by the ratio of the material velocity
to the speed of light. Here we show that this typically tiny effect is greatly
amplified in multilayer systems composed of resonantly absorbing atoms (e.g.
optically trapped 87Rb), which may exhibit ultra-narrow photonic band gaps. The
amplification of the effect is shown to be three orders of magnitude greater
than previous estimates for conventional photonic-band-gap materials, and
significant for material velocities of a few ms/s.Comment: 5 pages, 3 figure
Collapse of quasi-two-dimensional wet granular columns
This paper deals with the experimental characterization of the collapse of
wet granular columns in the pendular state, with the purpose of collecting data
on triggering and jamming phenomena in wet granular media. The final deposit
shape and the runout dynamics were studied for samples of glass beads, varying
particle diameter, liquid surface tension, and liquid amount. We show how the
runout distance decreases with increasing water amount (reaching a plateau for
) and increases with increasing Bond number, while the top and toe
angles and the final deposit height increase with increasing water amount and
decrease with decreasing Bond number. Dimensional analysis allowed to discuss
possible scalings for the runout length and the top and toe angles: a
satisfying scaling was found, based on the combination of Bond number and
liquid amount.Comment: 8 pages, 14 figure
Quantum theory of a polarization phase-gate in an atomic tripod configuration
We present the quantum theory of a polarization phase-gate that can be
realized in a sample of ultracold rubidium atoms driven into a tripod
configuration. The main advantages of this scheme are in its relative
simplicity and inherent symmetry. It is shown that the conditional phase shifts
of order can be attained.Comment: X International Conference on Quantum Optics, Minsk, Belaru
Commissioning of the ATLAS Muon Trigger System with early data
An overview of the early results on commissioning and performance of the ATLAS Muon Trigger System is shown. The ATLAS Muon Trigger has been designed to cope with the high interaction rate expected at the LHC. The presented
performance studies have been obtained using both cosmic-ray and 900GeV collision data
Transverse Fresnel-Fizeau drag effects in strongly dispersive media
A light beam normally incident upon an uniformly moving dielectric medium is
in general subject to bendings due to a transverse Fresnel-Fizeau light drag
effect. In conventional dielectrics, the magnitude of this bending effect is
very small and hard to detect. Yet, it can be dramatically enhanced in strongly
dispersive media where slow group velocities in the m/s range have been
recently observed taking advantage of the electromagnetically induced
transparency (EIT) effect. In addition to the usual downstream drag that takes
place for positive group velocities, we predict a significant anomalous
upstream drag to occur for small and negative group velocities. Furthermore,
for sufficiently fast speeds of the medium, higher order dispersion terms are
found to play an important role and to be responsible for peculiar effects such
as light propagation along curved paths and the restoration of the spatial
coherence of an incident noisy beam. The physics underlying this new class of
slow-light effects is thoroughly discussed
Coherent perfect absorption in one-sided reflectionless media
In optical experiments one-sided reflectionless (ORL) and coherent perfect absorption (CPA) are unusual scattering properties yet fascinating for their fundamental aspects and for their practical interest. Although these two concepts have so far remained separated from each other, we prove that the two phenomena are indeed strictly connected. We show that a CPA-ORL connection exists between pairs of points lying along lines close to each other in the 3D space-parameters of a realistic lossy atomic photonic crystal. The connection is expected to be a generic feature of wave scattering in non-Hermitian optical media encompassing, as a particular case, wave scattering in parity-time (PT) symmetric media
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