Locking classical correlations in quantum States.
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.
IBM Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA.
David P
DP
DiVincenzo
Michał
M
Horodecki
Debbie W
DW
Leung
John A
JA
Smolin
Barbara M
BM
Terhal