2002/06/18 by Carlton M. Caves, Christopher A. Fuchs, Ruediger Schack · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physreva.66.062111
published as Phys. Rev. A 66, 062111 (2002) · REVTEX 4, 19 pages, 1 postscript figure
arxiv created 2002/06/18 · arxiv updated 2009/12/01
Suppose N parties describe the state of a quantum system by N possibly different density operators. These N state assignments represent the beliefs of the parties about the system. We examine conditions for determining whether the N state assignments are compatible. We distinguish two kinds of procedures for assessing compatibility, the first based on the compatibility of the prior beliefs on which the N state assignments are based and the second based on the compatibility of predictive measurement probabilities they define. The first procedure leads to a compatibility criterion proposed by Brun, Finkelstein, and Mermin [BFM, Phys. Rev. A 65, 032315 (2002)]. The second procedure leads to a hierarchy of measurement-based compatibility criteria which is fundamentally different from the corresponding classical situation. Quantum mechanically none of the measurement-based compatibility criteria is equivalent to the BFM criterion.