Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dark-time decay of the retrieval efficiency of light stored as a Rydberg
  excitation in a noninteracting ultracold gas   We study the dark-time decay of the retrieval efficiency for light stored in
a Rydberg state in an ultracold gas of $^{87}$Rb atoms based on
electromagnetically induced transparency (EIT). Using low atomic density to
avoid dephasing caused by atom-atom interactions, we measure a $1/e$ time of 30
$\mu$s for the $80S$ state in free expansion. One of the dominant limitations
is the combination of photon recoil and thermal atomic motion at 0.2 $\mu$K. If
the 1064-nm dipole trap is left on, then the $1/e$ time is reduced to 13
$\mu$s, in agreement with a model taking differential light shifts and
gravitational sag into account. To characterize how coherent the retrieved
light is, we overlap it with reference light and measure the visibility $V$ of
the resulting interference pattern, obtaining $V> 90\%$ for short dark time.
Our experimental work is accompanied by a detailed model for the dark-time
decay of the retrieval efficiency of light stored in atomic ensembles. The
model is generally applicable for photon storage in Dicke states, such as in
EIT with $\Lambda$-type or ladder-type level schemes and in
Duan-Lukin-Cirac-Zoller single-photon sources. The model includes a treatment
of the dephasing caused by thermal atomic motion combined with net photon
recoil, as well as the influence of trapping potentials. It takes into account
that the signal light field is typically not a plane wave. The model maps the
retrieval efficiency to single-atom properties and shows that the retrieval
efficiency is related to the decay of fringe visibility in Ramsey spectroscopy
and to the spatial first-order coherence function of the gas.

31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin