Structure and parametrization of stochastic maps of density matrices

Sudarshan, E. C. G. ; Shaji, Anil (2003) Structure and parametrization of stochastic maps of density matrices Journal of Physics A: Mathematical and General, 36 (18). pp. 5073-5081. ISSN 0305-4470

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Official URL: http://iopscience.iop.org/0305-4470/36/18/312

Related URL: http://dx.doi.org/10.1088/0305-4470/36/18/312

Abstract

The most general evolution of the density matrix of a quantum 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. The positivity of the density matrix does not make the associated supermatrix positive though. If the map itself is positive, it is called completely positive and it has a simple parametrization. This is extended to all positive (not completely positive) maps. A general dynamical map that does not preserve the norm of the density matrices it acts on can be thought of as the contraction of a norm-preserving map of an extended system. The reconstruction of such extended dynamics is also given.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
ID Code:50975
Deposited On:27 Jul 2011 13:02
Last Modified:18 May 2016 05:05

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