Logical paradoxes in quantum computation

Abstract

The precise features of quantum theory enabling quantum computational power are unclear. Contextuality---the denial of a notion of classical physical reality---has emerged as a promising hypothesis: e.g. Howard et al. showed that the magic states needed to practically achieve quantum computation are contextual. Strong contextuality, as defined by Abramsky-Brandenburger, is an extremal form of contextuality describing systems that exhibit logically paradoxical behaviour. After introducing number-theoretic techniques for constructing exotic quantum paradoxes, we present large families of strongly contextual magic states that are computationally optimal in the sense that they enable universal quantum computation via deterministic injection of gates of the Clifford hierarchy. We thereby bolster a refinement of the resource theory of contextuality that emphasises the computational power of logical paradoxes.