Non-local correlations as an information theoretic resource

J Barrett, N Linden, S Massar, S Pironio, S Popescu, DA Roberts

Research output: Contribution to journalArticle (Academic Journal)peer-review


It is well known that measurements performed on spatially separated entangled quantum systems can give rise to correlations that are nonlocal, in the sense that a Bell inequality is violated. They cannot, however, be used for superluminal signaling. It is also known that it is possible to write down sets of "superquantum" correlations that are more nonlocal than is allowed by quantum mechanics, yet are still nonsignaling. Viewed as an information-theoretic resource, superquantum correlations are very powerful at reducing the amount of communication needed for distributed computational tasks. An intriguing question is why quantum mechanics does not allow these more powerful correlations. We aim to shed light on the range of quantum possibilities by placing them within a wider context. With this in mind, we investigate the set of correlations that are constrained only by the no-signaling principle. These correlations form a polytope, which contains the quantum correlations as a (proper) subset. We determine the vertices of the no-signaling polytope in the case that two observers each choose from two possible measurements with d outcomes. We then consider how interconversions between different sorts of correlations may be achieved. Finally, we consider some multipartite examples.
Translated title of the contributionNon-local correlations as an information theoretic resource
Original languageEnglish
Article numberArt. No. 022101
JournalPhysical Review A: Atomic, Molecular and Optical Physics
Volume71 (2)
Publication statusPublished - Feb 2005

Bibliographical note

Publisher: American Physical Soc
Other identifier: IDS number 904GK


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