Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum cryptography based on photon ``frequency'' states: example of a
  possible realization   A quantum cryptosystem is proposed using single-photon states with different
frequency spectra as information carriers. A possible experimental
implementation of the cryptosystem is discussed.

25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg