Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Photon-photon gate via the interaction between two collective Rydberg
  excitations
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
2
The categories of this paper are: math
14
The categories of this paper are: math-ph