Separable approximation for mixed states of composite quantum systems
arXiv:quant-ph/0104098 · doi:10.1103/PhysRevA.64.052302
Abstract
We describe a purely algebraic method for finding the best separable approximation to a mixed state of a composite 2x2 quantum system, consisting of a decomposition of the state into a linear combination of a mixed separable part and a pure entangled one. We prove that, in a generic case, the weight of the pure part in the decomposition equals the concurrence of the state.
13 pages, no figures; minor changes; accepted for publication in PRA
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