Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum effects in the collective light scattering by coherent atomic
  recoil in a Bose-Einstein condensate   We extend the semiclassical model of the collective atomic recoil laser
(CARL) to include the quantum mechanical description of the center-of-mass
motion of the atoms in a Bose-Einstein condensate (BEC). We show that when the
average atomic momentum is less than the recoil momentum $\hbar\vec q$, the
CARL equations reduce to the Maxwell-Bloch equations for two momentum levels.
In the conservative regime (no radiation losses), the quantum model depends on
a single collective parameter, $\rho$, that can be interpreted as the average
number of photons scattered per atom in the classical limit. When $\rho\gg 1$,
the semiclassical CARL regime is recovered, with many momentum levels populated
at saturation. On the contrary, when $\rho\le 1$, the average momentum
oscillates between zero and $\hbar\vec q$, and a periodic train of $2\pi$
hyperbolic secant pulses is emitted. In the dissipative regime (large radiation
losses) and in a suitable quantum limit, a sequential superfluorescence
scattering occurs, in which after each process atoms emit a $\pi$ hyperbolic
secant pulse and populate a lower momentum state. These results describe the
regular arrangement of the momentum pattern observed in recent experiments of
superradiant Rayleigh scattering from a BEC.

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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: physics
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The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: astro-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: ao-sci