Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Concepts of a quantum information theory of many letters   A theoretical framework is presented allowing the treatment of quantum
messages with components of variable length. To this aim a many-letter space,
similiar to the Fock space, is constructed, generalizing the standard quantum
information theory of block messages of fixed length. In the many-letter space
a length operator can be defined measuring the length of a quantum message,
whose eigenspaces are the block Hilbert spaces used in the standard theory.

26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
2
The categories of this paper are: math
18
The categories of this paper are: econ
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th