Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The role of the stress trap in polariton quasiequilibrium condensation
  in GaAs microcavities   Recent experiments have shown several effects indicative of Bose-Einstein
condensation in polaritons in GaAs-based microcavity structures when a harmonic
potential trap for the two-dimensional polaritons is created by applied stress.
These effects include both real-space and momentum-space narrowing, first-order
coherence, and onset of linear polarization above a particle density threshold.
Similar effects have been seen in systems without traps, raising the question
of how important the role of the trap is in these experiments. In this paper we
present results for both trapped conditions and resonant, non-trapped
conditions in the same sample. We find that the results are qualitatively
different, with two distinct types of transitions. At low density in the trap,
the polaritons remain in the strong-coupling regime while going through the
threshold for onset of coherence; at higher density, there is a different
threshold behavior which occurs with weak coupling and can be identified with
lasing; this transition occurs both with and without a trap.

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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
1
The categories of this paper are: cs