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Locking classical correlation in quantum states

David DiVincenzo·Michal Horodecki·Debbie Leung·John Smolin·Barbara Terhal
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Abstract

We show that there exist bipartite quantum states which contain large hidden classical correlation that can be unlocked by a disproportionately small amount of classical communication. In particular, there are $(2n+1)$-qubit states for which a one bit message doubles the optimal classical mutual information between measurement results on the subsystems, from $n/2$ bits to $n$ bits. States exhibiting this behavior need not be entangled. We study the range of states exhibiting this phenomenon and bound its magnitude.

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David DiVincenzo, Michal Horodecki, Debbie Leung, John Smolin, Barbara Terhal. 2003-03-14. Locking classical correlation in quantum states. https://doi.org/10.1103/physrevlett.92.067902

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