Maximally epistemic interpretations of the quantum state and contextuality

Understand

We examine the relationship between quantum contextuality (in both the standard Kochen-Specker sense and in the generalised sense proposed by Spekkens) and models of quantum theory in which the quantum state is maximally epistemic.

• We find that preparation noncontextual models must be maximally epistemic, and these in turn must be Kochen-Specker noncontextual.
• This implies that the Kochen-Specker theorem is sufficient to establish both the impossibility of maximally epistemic models and the impossibility of preparation noncontextual models.
• The implication from preparation noncontextual to maximally epistemic then also yields a proof of Bell's theorem from an EPR-like argument.