Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structure and Parametrization of Stochastic Maps of Density Matrices   The generic linear evolution of the density matrix of a system with a
finite-dimensional state space is by stochastic maps which take a density
matrix linearly into the set of density matrices. These dynamical stochastic
maps form a linear convex set that may be viewed as supermatrices. The property
of hermiticity of density matrices renders an associated supermatrix hermitian
and hence diagonalizable; but the positivity of the density matrix does not
make this associated supermatrix positive. If it is positive, the map is called
completely positive and they have a simple parametrization. This is extended to
all positive (not completely positive) maps. A contraction of a norm-preserving
map of the combined system can be contracted to obtain all dynamical maps. The
reconstruction of the extended dynamics is given.

30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
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The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
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The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs