The exclusivity principle and the set of quantun correlations

Abstract

Quantum theory provides a set of rules to predict probabilities of different outcomes in different experimental settings. While it predicts probabilities which match, with extreme accuracy, the data from actually performed experiments, it has some peculiar properties which deviate from how we normally think about systems which have a probabilistic description. Two of the strange characteristics are contextuality and nonlocality. The former tells us that we cannot think about a measurement on a quantum system as revealing a property which is independent of the set of measurements we chose to make. The latter, describes how measurements made by spatially separated observers in a multipartite quantum system can exhibit extremely strong correlations. Contextuality and nonlocality are the most striking features of quantum theory. We believe that a complete understanding of these features may be the most important step towards understanding the whole theory.