Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Long-lived nanosecond spin coherence in high-mobility 2DEGs confined in
  double and triple quantum wells
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph