Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-order harmonic generation at high laser intensities beyond the
  tunnel regime   We present studies of high-order harmonic generation (HHG) at laser
intensities well above saturation. We use driving laser pulses which present a
particular electron dynamics in the turn-on stage. Our results predict an
increasing on the harmonic yield, after an initial dropping, when the laser
intensity is increased. This fact contradicts the general belief of a
progressive degradation of the harmonic emission at ultrahigh intensities. We
have identified a particular set of trajectories which emerges in the turn-on
stage of these singular laser pulses, responsible of the unexpected growth on
the harmonic efficiency at this high intensity regime. Our study combines two
complementary approaches: classical analysis and full quantum mechanical
calculations resulting from the numerical integration of the 3-dimensional
time-dependent Schr\"odinger equation complemented with the time-frequency
analysis.

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The categories of this paper are: solv-int
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The categories of this paper are: econ
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
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The categories of this paper are: eess
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg