218 research outputs found
Dynamics of matter-wave and optical fields in superradiant scattering from Bose-Einstein condensates
We study superradiant scattering off Bose-Einstein condensates by solving the
semiclassical Maxwell-Schroedinger equations describing the coupled dynamics of
matter-wave and optical fields. Taking the spatial dependence of these fields
along the condensate axis into account, we are able to reproduce and explain
many of the characteristic features observed in the experiments of Inouye et
al. [Science 285, 571 (1999)] and Schneble et al. [Science 300, 475 (2003)],
such as the shape of the atomic side-mode distributions for forward and
backward scattering, the spatial asymmetry between forward and backward side
modes, and the depletion of the condensate center observed for forward
scattering.Comment: 4 pages, 2 figure
The impact of the 1996 Summer Olympic Games on employment and wages in Georgia
Using the standard differences-in-differences (DD) technique and a modified DD technique in the slopes, this paper determines that hosting the 1996 Summer Olympic Games boosted employment by 17% in the counties of Georgia affiliated with and close to Olympic activity, relative to employment increases in other counties in Georgia (the rate of growth increased by 0.002 percentage points per quarter). Estimation of a random-growth model confirms a positive impact of the Olympics on employment. In addition, the employment impact is shown not to be merely a "metropolitan statistical area (MSA) effect"; employment in the northern Olympic venue areas was found to increase 11% more post- versus pre-Olympics than it did in other, similar southern MSAs. The evidence of an Olympic impact on wages is weak
Correlated directional atomic clouds via four-heterowave mixing
We investigate the coherence properties of pairs of counter-propagating
atomic clouds, produced in superradiant Rayleigh scattering off atomic
condensates. It is shown that these clouds exhibit long-range spatial coherence
and strong nonclassical density cross-correlations, which make this scheme a
promising candidate for the production of highly directional nonclassically
correlated atomic pulses.Comment: 12 pages, 3 figure
Condensation temperature of interacting Bose gases with and without disorder
The momentum-shell renormalization group (RG) is used to study the
condensation of interacting Bose gases without and with disorder. First of all,
for the homogeneous disorder-free Bose gas the interaction-induced shifts in
the critical temperature and chemical potential are determined up to second
order in the scattering length. The approach does not make use of dimensional
reduction and is thus independent of previous derivations. Secondly, the RG is
used together with the replica method to study the interacting Bose gas with
delta-correlated disorder. The flow equations are derived and found to reduce,
in the high-temperature limit, to the RG equations of the classical
Landau-Ginzburg model with random-exchange defects. The random fixed point is
used to calculate the condensation temperature under the combined influence of
particle interactions and disorder.Comment: 7 pages, 2 figure
Spatial effects in superradiant Rayleigh scattering from Bose-Einstein condensates
We present a detailed theoretical analysis of superradiant Rayleigh
scattering from atomic Bose-Einstein condensates. A thorough investigation of
the spatially resolved time-evolution of optical and matter-wave fields is
performed in the framework of the semiclassical Maxwell-Schroedinger equations.
Our theory is not only able to explain many of the known experimental
observations, e.g., the behavior of the atomic side-mode distributions, but
also provides further detailed insights into the coupled dynamics of optical
and matter-wave fields. To work out the significance of propagation effects, we
compare our results to other theoretical models in which these effects are
neglected.Comment: 14 pages, 13 figure
Early Stage of Superradiance from Bose-Einstein Condensates
We investigate the dynamics of matter and optical waves at the early stage of
superradiant Rayleigh scattering from Bose-Einstein Condensates. Our analysis
is within a spatially dependent quantum model which is capable of providing
analytic solutions for the operators of interest. The predictions of the
present model are compared to the predictions of a closely related mean field
model, and we provide a procedure that allows one to calculate quantum
expectation values by averaging over semiclassical solutions. The coherence
properties of the outgoing scattered light are also analyzed, and it is shown
that the corresponding correlation functions may provide detailed information
about the internal dynamics of the system.Comment: 27 pages, 8 figure
Passage-time statistics of superradiant light pulses from Bose-Einstein condensates
We discuss the passage-time statistics of superradiant light pulses generated
during the scattering of laser light from an elongated atomic Bose-Einstein
condensate. Focusing on the early-stage of the phenomenon, we analyze the
corresponding probability distributions and their scaling behaviour with
respect to the threshold photon number and the coupling strength. With respect
to these parameters, we find quantities which only vary significantly during
the transition between the Kapitza Dirac and the Bragg regimes. A possible
connection of the present observations to Brownian motion is also discussed.Comment: Close to the version published in J. Phys.
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