Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of a Cooperative Radiation Force in the Presence of Disorder   Cooperative scattering of light by an extended object such as an atomic
ensemble or a dielectric sphere is fundamentally different from scattering from
many point-like scatterers such as single atoms. Homogeneous distributions tend
to scatter cooperatively, whereas fluctuations of the density distribution
increase the disorder and suppress cooperativity. In an atomic cloud, the
amount of disorder can be tuned via the optical thickness, and its role can be
studied via the radiation force exerted by the light on the atomic cloud.
Monitoring cold $^{87}\text{Rb}$ atoms released from a magneto-optical trap, we
present the first experimental signatures of radiation force reduction due to
cooperative scattering. The results are in agreement with an analytical
expression interpolating between the disorder and the cooperativity-dominated
regimes.

20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
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The categories of this paper are: stat
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex