Bell Nonlocality and the Reality of Quantum Wavefunction

TL;DR

This paper introduces a new $$-ontology theorem demonstrating that quantum nonlocality cannot be explained by models where the wavefunction is merely knowledge, strengthening the case for the wavefunction's reality.

Contribution

It presents a $$-ontology theorem that does not assume the absence of holistic properties, unlike previous theorems, and links Bell nonlocality to the reality of the wavefunction.

Findings

Quantum nonlocality cannot be explained by $$-epistemic models.

Derived a threshold bound on epistemicity compatible with quantum statistics.

Strengthened the argument for the ontic nature of the wavefunction.

Abstract

Status of quantum wavefunction is one of the most debated issues in quantum foundations -- whether it corresponds directly to the reality or just represents knowledge or information about some aspect of reality. In this letter we propose a {\it $\psi$-ontology} theorem that excludes a class of ontological explanations where quantum wavefunction is treated as mere information. Our result, unlike the acclaimed Pusey-Barrett-Rudolph's theorem, does not presume the absence of holistic ontological properties for product quantum preparations. At the core of our derivation we utilize the seminal no-go result by John S. Bell that rules out any local realistic world view for quantum theory. We show that the observed phenomenon of quantum nonlocality cannot be incorporated in a class of $\psi$-epistemic models. Using the well known Clauser-Horne-Shimony-Holt inequality we obtain a threshold bound on the degree of epistemicity above which the ontological models are not compatible with quantum statistics.