Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-subband system in quantizing magnetic field: Probing many-body gap
  by non-equilibrium phonons   We study the many-body effects in a two-subband quasi-two-dimensional
electron system in a quantizing magnetic field at filling factor three. A
manifestation of these effects in the phonon absorption spectroscopy is
discussed. The electron system is mapped onto a two-level system with the
separation between levels determined by the intersubband splitting and the
cyclotron energy. The electron-electron interaction enhances the excitation
gap, which exists at all values of the interlevel splitting. This results in a
single-peak structure of the phonon absorption rate as a function of magnetic
field, instead of the double-peak structure for non-interacting electrons.

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The categories of this paper are: alg-geom
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph