Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Spectrally pure single photons at telecommunications wavelengths using
  commercial birefringent optical fiber
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
2
The categories of this paper are: math
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org