Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Terahertz sensing by beryllium and silicon delta-doped GaAs/AlAs quantum
  wells
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys