A demonstration that classical gravity does not produce entanglement

TL;DR

This paper argues that classical gravity cannot produce entanglement between particles, clarifying misconceptions in quantum gravity experiments and emphasizing the need for non-classical explanations if entanglement is observed.

Contribution

It provides a Newton-Cartan analysis demonstrating that classical gravity cannot mediate entanglement, clarifying the interpretation of quantum gravity experiments.

Findings

Classical gravity cannot produce entanglement.

Observed entanglement implies non-classical effects.

Clarifies interpretation of gravitationally induced entanglement experiments.

Abstract

Once again, dispute has arisen over the interpretation of proposed quantum information theory experiments to probe the quantum nature of gravity by testing for gravitationally induced entanglement (GIE) between two spatially separated massive particles ([2] vs. [16, 17]; further contributions in [11, 13]). The confusion appears to reside in interpreting applications of a Hamiltonian formalism. But classical gravity cannot mediate entanglement on independent grounds. A Newton-Cartan analysis shows that if gravity is classical, a mediator, and entanglement is observed as an outcome of performing a GIE experiment, something other than gravity must have supplied the (virtual) force needed during the experiment to produce the effect.