Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A 5.7 THz GaN/AlGaN quantum cascade detector based on polar step quantum
  wells
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph