Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of Superfluorescence from a Spontaneous Coherence of
  Excitons in ZnTe Crystal: Evidence for Bose-Einstein Condensation of
  Excitons?   Superfluorescence (SF) is the emission from a dense coherent system in
population inversion, formed from an initially incoherent ensemble. This is
characterised by an induction time (t_D) for the spontaneous development of the
macroscopic quantum coherence. Here we report detailed observation of SF on
ultrafast timescale from a quantum ensemble of coherent excitons in highly
excited intrinsic bulk ZnTe single crystal at 5 K, showing a characteristic t_D
from 40 ps to 10 ps, quantum noise and fluctuations, and quantum beating and
ringing. From this clear observation of SF from a spontaneous coherence of
excitons we infer that this is indicative of the formation of BEC of excitons
on an ultrafast timescale.

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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys