Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-perturbative generation of above-threshold harmonics from
  pre-excited argon atoms in intense mid-infrared laser fields   We experimentally investigate the generation of above-threshold harmonics
completely from argon atoms on an excited state using mid-infrared femtosecond
laser pulses. The highly nonlinear dependences of the observed signal on the
pulse energy and polarization of the driver laser pulses indicate its
non-perturbative characteristic.

16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
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The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ