Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin-Squeezing and Light Entanglement in Coherent Population Trapping   We show that high squeezing and entanglement can be generated at the output
of a cavity containing atoms interacting with two fields in a Coherent
Population Trapping situation, on account of a non-linear Faraday effect
experienced by the fields close to a dark-state resonance in a cavity.
Moreover, the cavity provides a feedback mechanism allowing to reduce the
quantum fluctuations of the ground state spin, resulting in strong steady state
spin-squeezing.

12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th