Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Plasmons in tunnel-coupled graphene layers: backward waves with quantum
  cascade gain
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga