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arXiv · 1501.06855

Hierarchy of efficiently computable and faithful lower bounds to quantum discord

Marco Piani
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Abstract

Quantum discord expresses a fundamental non-classicality of correlations more general than quantum entanglement. We combine the no-local-broadcasting theorem, semidefinite-programming characterizations of quantum fidelity and quantum separability, and a recent breakthrough result of Fawzi and Renner about quantum Markov chains to provide a hierarchy of computationally efficient lower bounds to quantum discord. Such a hierarchy converges to the surprisal of measurement recoverability introduced by Seshadreesan and Wilde, and provides a faithful lower bound to quantum discord already at the lowest non-trivial level. Furthermore, the latter constitutes by itself a valid discord-like measure of the quantumness of correlations.

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Marco Piani. 2015-01-27. Hierarchy of efficiently computable and faithful lower bounds to quantum discord. https://doi.org/10.1103/physrevlett.117.080401

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