Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Natural capacity of a system of two two-level atoms as a quantum
  information channel   A system of two closely spaced atoms interacting through a vacuum
electromagnetic field is considered. It is demonstrated that radiative decay in
such a system resulting from photon exchange gives rise to a definite amount of
information related to interatomic communication. Joint distributions of
detection probabilities of atomic quanta and the corresponding amount of
communication information are calculated.

8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph