INL – International Iberian Nanotechnology Institute, Portugal, rui.soaresbarbosa@inl.int
Vorob'ev’s theorem characterises those configurations of contexts (i.e. measurement scenarios) which are inherently classical in the sense that the no-signalling or no-disturbance condition is enough to ensure locality or non-contextuality. Even if at first glance these scenarios may look a bit boring from the point of view of contextuality, we will discuss how Vorob'ev’s result can be applied to provide an elegant structural explanation for two related phenomena: (1) monogamy of non-locality, which establishes a trade-off between strength of non-locality shared between a party and multiple others, and (2) locality of average macroscopic behaviour, regardless of the non-classicality present in the microscopic state of a system. Since Vorob'ev’s theorem depends solely on the compatibility structure of measurements, these results hold not just for quantum theory, but for any empirical behaviours satisfying only the no-signalling condition.