The status of determinism in noncontextual models of quantum theory

          @misc{ pirsa_PIRSA:10120065,
            doi = {10.48660/10120065},
            url = {https://pirsa.org/10120065},
            author = {Spekkens, Robert},
            keywords = {Quantum Foundations},
            language = {en},
            title = {The status of determinism in noncontextual models of quantum theory},
            publisher = {Perimeter Institute},
            year = {2010},
            month = {dec},
            note = {PIRSA:10120065 see, \url{https://pirsa.org}}
          }
          

Abstract

In an ontological model of quantum theory that is Bell-local, one can assume without loss of generality that the outcomes of measurements are determined deterministically by the ontic states (i.e. the values of the local hidden variables). The question I address in this talk is whether such determinism can always be assumed in a noncontextual ontological model of quantum theory, in particular whether it can be assumed for nonprojective measurements. While it is true that one can always represent a measurement by a deterministic response function by incorporating ancillary degrees of freedom into one's description (for instance those of the apparatus), I show that in moving to such a representation, one typically loses the warrant to apply the assumption of measurement noncontextuality. The implications for experimental tests of measurement noncontextuality will be discussed.