title: Unified framework for correlations in terms of local quantum observables.
abstract: We provide a unified framework for nonsignalling quantum and classical multipartite correlations, allowing all to be written as the trace of some local (quantum) measurements multiplied by an operator. The properties of this operator define the corresponding set of correlations. We then show that if the theory is such that all local quantum measurements are possible, one obtains the correlations corresponding to the extension of Gleason's Theorem to multipartite systems. Such correlations coincide with the quantum ones for one and two parties, but we prove the existence of a gap for three or more parties.
authors.affiliation: ICFO-Institut de Ciències Fotòniques, E-08860 Castelldefels, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Acín
authors.forename: R
authors.initials: R
authors.lastname: Augusiak
authors.forename: D
authors.initials: D
authors.lastname: Cavalcanti
authors.forename: C
authors.initials: C
authors.lastname: Hadley
authors.forename: J K
authors.initials: JK
authors.lastname: Korbicz
authors.forename: M
authors.initials: M
authors.lastname: Lewenstein
authors.forename: Ll
authors.initials: L
authors.lastname: Masanes
authors.forename: M
authors.initials: M
authors.lastname: Piani