An Epistemic model of Quantum State with Ontic Probability Amplitude

Abstract

We first prove that ontological models of the quantum state which are capable of reproducing the Born probability rule and fall in the class of $\psi$-epistemic models are inconsistent with the Sch{\"o}dinger time evolution. We then model the ontic state space as a complex projective Hilbert space that embeds the projective Hilbert space of quantum mechanics and define a minimalist epistemic state as an average over a set of "hidden states" in the larger space. We show that such a model incorporates probability amplitudes and admits an epistemic interpretation of quantum states. Finally, we prove a second theorem to show that such a model is compatible with locality but ontic models are not.