Probing the link between contextuality and quantum coherences using the quantum Cheshire cat paradox

We analyse the quantum Cheshire cat using contextuality theory, to see if this can tell us anything about how best to interpret this paradox. We show that this scenario can be analysed using the relation between three different measurements, which seem to result in a logical contradiction. We discuss how this contextual behaviour links to weak values, and coherences between states prohibited by either the pre-selection or the postselection. Rather than showing a property of the particle is disembodied, the quantum Cheshire cat instead demonstrates the effects of these coherences, which are typically found in pre- and postselected systems. Our results shed a surprising new light on the relation between weak values and contextuality, a key resource for quantum computing. (This talk is based on the published paper, Contextuality, Coherences, and Quantum Cheshire Cats (Jonte R Hance et al 2023 New J. Phys. 25 113028)).