Finite de Finetti theorem for conditional probability ...
Posted by ~Ray @ 2008-03-16 00:23:42
Finite de Finetti theorem for conditional probability distributions describing physical theories
Centre for Quantum Computation. DAMTP. University of Cambridge. Cambridge CB3 0WA. UKInstitute for Quantum Information. California initiate of Technology. Pasadena CA 91125. USACentrum voor Wiskunde en Informatica. Kruislaan 413. 1098 SJ Amsterdam. The Netherlands
consider. We work in a general framework where the state of a physical system is defined by its behaviour under measurement and the relation between different systems is constrained by a no-signalling principle. We characterize symmetric states in such theories showing that their marginals can be approximated by convex combinations of independent and identical conditional probability distributions. This generalizes the classical finite de Finetti theorem of Diaconis and Freedman. Our results have application to the foundations of physics quantum cryptography and the study of classical channels. In particular they bear on to correlations obtained from quantum states change surface when there is no move on the local dimension so that known finite quantum de Finetti theorems cannot be used. [ADVERTHERE]Related article:
http://eprintweb.org/S/article/quant-ph/0712.0916
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