TY - JOUR

T1 - Maximum observable correlation for a bipartite quantum system

AU - Hall, Michael J.W.

AU - Andersson, Erika

AU - Brougham, Thomas

PY - 2006

Y1 - 2006

N2 - The maximum observable correlation between the two components of a bipartite quantum system is a property of the joint density operator, and is achieved by making particular measurements on the respective components. For pure states it corresponds to making measurements diagonal in a corresponding Schmidt basis. More generally, it is shown that the maximum correlation may be characterized in terms of a correlation basis for the joint density operator, which defines the corresponding (nondegenerate) optimal measurements. The maximum coincidence rate for spin measurements on two-qubit systems is determined to be (1+s)2, where s is the spectral norm of the spin correlation matrix, and upper bounds are obtained for n -valued measurements on general bipartite systems. It is shown that the maximum coincidence rate is never greater than the computable cross norm measure of entanglement, and a much tighter upper bound is conjectured. Connections with optimal state discrimination and entanglement bounds are briefly discussed.

AB - The maximum observable correlation between the two components of a bipartite quantum system is a property of the joint density operator, and is achieved by making particular measurements on the respective components. For pure states it corresponds to making measurements diagonal in a corresponding Schmidt basis. More generally, it is shown that the maximum correlation may be characterized in terms of a correlation basis for the joint density operator, which defines the corresponding (nondegenerate) optimal measurements. The maximum coincidence rate for spin measurements on two-qubit systems is determined to be (1+s)2, where s is the spectral norm of the spin correlation matrix, and upper bounds are obtained for n -valued measurements on general bipartite systems. It is shown that the maximum coincidence rate is never greater than the computable cross norm measure of entanglement, and a much tighter upper bound is conjectured. Connections with optimal state discrimination and entanglement bounds are briefly discussed.

UR - http://www.scopus.com/inward/record.url?scp=33845656921&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.74.062308

DO - 10.1103/PhysRevA.74.062308

M3 - Article

SN - 1050-2947

VL - 74

JO - Physical Review A - Atomic, Molecular, and Optical Physics

JF - Physical Review A - Atomic, Molecular, and Optical Physics

IS - 6

M1 - 062308

ER -