Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Carrier heating and high-order harmonics generation in doped graphene by
  a strong ac electric field   The nonlinear response of electrons (holes) in doped graphene on ac pumping
is considered theoretically for the frequency region above the energy
relaxation rate but below the momentum and carrier-carrier scattering rates.
Temporally-dependent heating of electrons by a strong ac field, which is
described within the energy balance approach, leads to an effective generation
of high-order harmonics. The efficiency of up-conversion of the 1 mm radiation
into the third harmonic by a single-layer graphene is about 10^{-7} at pumping
level ~100 kW/cm^2, room temperature, and concentration ~5 x 10^{11} cm^{-2}.

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The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
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The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
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The categories of this paper are: chem-ph