Abstract

This seminar is based on an essay written last year during part III of the mathematical tripos. The concept of non-locality in quantum mechanics is introduced with a brief description of the EPR -Bohm experiment and the CHSH inequality. Non-locality beyond quantum mechanics is presented in terms of correlation boxes. These are abstract hypothetical systems that can be separated by arbitrary large distances but that maintain some correlations. Bipartite and tripartite correlation boxes are described. Although quantum mechanics violates the CHSH inequality, it does not violate it to its maximum value. Some bipartite correlation boxes, the PR boxes, do violate the CHSH inequality to its maximum algebraical possible value. The usefulness of the PR boxes in key distribution is presented.