Reconciling the ontic and epistemic views in quantum contextuality

Abstract

The classic debate between Einstein and Bohr over a realistic interpretation of quantum mechanics can be cast in terms of the measurement problem: Is there an underlying ontic state prior to measurement which maps deterministically to the measured outcome? According to the Kochen-Specker theorem, such a view is patently inconsistent with quantum theory, leading to the paradox of quantum contextuality. This result, however, relies upon the (arguably unwarranted) assumption that the ontic state remains unchanged through the process of measurement and attendant interaction with the measuring device. By relaxing this assumption, it will be shown that one is able to maintain a realistic view of a pre-existing ontic state, as Einstein insisted, while allowing for changes in that ontic state relative to the chosen measurement, in accordance with Bohr. In this view, the wavefunction respresents an epistemic ensemble of ontological states, corresponding to, say, a particular preparation procedure, and its collapse is a selection of and dynamical process on one member of that ensemble. The specific case of the Mermin-Peres square will be considered, both for its simplicity and its connection to recent experimental tests of quantum contextuality.