Limited preparation contextuality in quantum theory and its relation to the Cirel'son bound

The Kochen-Specker (KS) theorem lies at the heart of the foundations of quantum mechanics. It establishes the impossibility of explaining predictions of quantum theory by any noncontextual ontological model. Spekkens generalized the notion of KS contextuality in [Phys. Rev. A 71, 052108 (2005)PLRAAN1050-294710.1103/PhysRevA.71.052108] for arbitrary experimental procedures (preparation, measurement, and transformation procedures). Interestingly, later on it was shown that preparation contextuality powers parity-oblivious multiplexing [Phys. Rev. Lett. 102, 010401 (2009)PRLTAO0031-900710.1103/PhysRevLett.102.010401], a two-party information theoretic game. Thus, using resources of a given operational theory, the maximum success probability achievable in such a game suffices as a bona fide measure of preparation contextuality for the underlying theory. In this work we show that preparation contextuality in quantum theory is more restricted compared to a general operational theory known as box world. Moreover, we find that this limitation of quantum theory implies the quantitative bound on quantum nonlocality as depicted by the Cirel'son bound.