Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Propagation-induced limits to high harmonic generation in 3D Dirac
  semimetals   3D Dirac semimetals (DSMs) are promising materials for terahertz high
harmonic generation (HHG). We show that 3D DSMs' high nonlinearity opens up a
regime of nonlinear optics where extreme subwavelength current density features
develop within nanoscale propagation distances of the driving field. Our
results reveal orders-of-magnitude enhancement in HHG intensity with thicker 3D
DSM films, and show that these subwavelength features fundamentally limit HHG
enhancement beyond an optimal film thickness. This decrease in HHG intensity
beyond the optimal thickness constitutes an effective propagation-induced
dephasing. Our findings highlight the importance of propagation dynamics in
nanofilms of extreme optical nonlinearity.

13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio