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Separable approximation for mixed states of composite quantum systems

Thomas Wellens·Marek Kus
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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.

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Thomas Wellens, Marek Kus. 2001-07-23. Separable approximation for mixed states of composite quantum systems. https://doi.org/10.1103/physreva.64.052302

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