Comment on Classical-Gravity--Quantum-Matter Claims About Gravity-Mediated Entanglement

TL;DR

This paper critiques claims that classical gravity can mediate entanglement between quantum masses, clarifying the conditions under which such entanglement can or cannot be generated, and reaffirming the significance of gravity-mediated entanglement as evidence of quantum gravity.

Contribution

It provides a model-independent channel theoretic reformulation of the critique on gravity-mediated entanglement claims and clarifies the distinction between activating existing entanglement and genuine mediation.

Findings

In the nonrelativistic limit, the interaction is ultra local and does not generate entanglement.

The critique is reformulated in a model-independent channel theoretic framework.

Observation of gravity-mediated entanglement remains a strong indicator of nonclassical gravitational degrees of freedom.

Abstract

A recent paper by Aziz and Howl (Nature 2025) argues that, once quantum matter is described at the level of quantum field theory and coupled to a classical gravitational field, higher order processes can generate entanglement between two spatially separated masses. A contemporaneous critical note (Marletto, Oppenheim, Vedral, Wilson, arXiv:2511.07348v1) shows that, in the actual nonrelativistic limit employed there, the interaction becomes ultra local, the total unitary factorizes, and no entanglement is generated from a product input. In this comment we (i) restate the core point of that critique, (ii) give a channel theoretic reformulation that makes the conclusion model independent, and (iii) clarify the distinction between activation of entanglement in already quantum matter and genuine mediation of entanglement by a classical field. Once these clarifications are in place, the standard BMV inference that observation of gravity mediated entanglement strongly indicates nonclassical gravitational degrees of freedom remains intact.