Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalous phase matching through inter sub-cycle interference   Providing efficient nonlinear optical frequency conversion is essential for
numerous applications. Fundamentally, dispersion limits the efficiency of such
processes through mismatch of the phase velocities and the group velocities of
the involved optical waves. We reveal a dispersion condition at which,
surprisingly, phase and group velocity mismatch act together to provide
efficient optical frequency conversion. We demonstrate this condition
numerically for the process of high-harmonic-generation. This finding could be
valuable to the theory and practice of nonlinear optical frequency conversion
in general.

2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas