Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Invariant states of quantum birth and death chains   A sufficient condition is given for a class of quantum birth and death chains
on the non-negative integers to possess invariant states. The result is applied
to generalised one-atom masers and to the Jaynes-Cummings one-atom maser with
random interaction time and not necessarily diagonal atomic states.

19
The categories of this paper are: eess
1
The categories of this paper are: cs
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas