The Fundamental Sharpness of Measurements Limits Contextuality in Arbitrary Physical Theories

Abstract

Quantum theory is contextual, but is not the most contextual point in the space of all conceivable theories. A natural question is what physical principles, if any, are responsible for the exact amount of contextuality that we observe in nature. I propose that quantum contextuality may arise from the balance between two desiderata: the requirement that every measurement can be realized from a repeatable and minimally disturbing measurement and the requirement that every state can be generated from a pure state. Both requirements are incarnations of the same overarching principle, namely that empirical observations must be compatible with a deeper level of description characterized by maximal knowledge. References for this talk: G. Chiribella and X. Yuan, Measurement sharpness cuts nonlocality and contextuality in every physical theory, https://arxiv.org/abs/1404.3348; G. Chiribella and X. Yuan, Bridging the gap between general probabilistic theories and the device-independent framework for nonlocality and contextuality, Information and Computation 250, 15 (2016).