Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum key distribution over 30km of standard fiber using energy-time
  entangled photon pairs: a comparison of two chromatic dispersion reduction
  methods
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat