Non-locality, contextuality and graphs

Adan Cabello

Universidad de Sevilla

There is a curious connection between physics and graph theory: for some games and for any Bell and non-contextual inequality, the classical/local/non-contextual bound is given by the so-called independence number of the graph in which vertices represent propositions tested in the experiment and edges link propositions that cannot be simultaneously true. More interestingly, the maximum quantum value is given (or upper bounded) by the so-called Lovasz number of the graph, while the maximum value attainable under the assumption that the sum of probabilities of exclusive propositions cannot be larger than 1 is given by the so-called fractional packing number. We show how to use these connections to identify interesting experiments, and report some recent theoretical and experimental developments.

Date: 24 November 2011

Time: 14:30 h

Place: Dpto. Física Teórica I, 3rd floor Seminar Lecture room. Facultad de Ciencias Físicas UCM