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Phys. Rev. Lett. 92, 067902 (2004) [4 pages]

Locking Classical Correlations in Quantum States

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David P. DiVincenzo1,2, Michał Horodecki3, Debbie W. Leung1,2,4, John A. Smolin1, and Barbara M. Terhal1,2
1IBM Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA
2Institute for Quantum Information, California Institute of Technology, Pasadena, California 91125-8100, USA
3Institute of Theoretical Physics and Astrophysics, University of Gdańsk, 80–952 Gdańsk, Poland
4Mathematical Science Research Institute, 1000 Centennial Drive, Berkeley, California 94720, USA

Received 13 March 2003; published 12 February 2004

We show that there exist bipartite quantum states which contain a large locked classical correlation that is 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. This phenomenon is impossible classically. However, states exhibiting this behavior need not be entangled. We study the range of states exhibiting this phenomenon and bound its magnitude.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.92.067902
DOI:
10.1103/PhysRevLett.92.067902
PACS:
03.67.–a
 
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