Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Calculation of the nonlinear response functions of intra-exciton
  transitions in two-dimensional transition metal dichalcogenides   In this paper, we study the third-order nonlinear optical response due to
transitions between excitonic levels in two-dimensional transition metal
dichalcogeniedes. To accomplish this, we use methods not applied to the
description of excitons in two-dimensional materials so far and combined with a
variational approach to describe the $1s$ excitonic state. The aforementioned
transitions allow to probe dark states which are not revealed in absorption
experiments. We present general formulas capable of describing any third-order
process. The specific case of two-photon absorption in WSe2 is studied. The
case of the circular well is also studied as a benchmark of the theory.

25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex