Is gravitational entanglement evidence for the quantization of spacetime?

TL;DR

Experiments testing gravitationally induced entanglement aim to determine if gravity must be quantized, but this paper presents a model showing classical spacetime can also generate entanglement, challenging previous assumptions.

Contribution

The paper introduces a parametrized model based on de Broglie-Bohm theory demonstrating that classical spacetime can produce entanglement, countering claims that only quantum gravity can do so.

Findings

Classical spacetime models can generate entanglement.

Counterexample to the claim that entanglement implies quantum gravity.

Challenges the interpretation of gravitational entanglement as evidence for quantization.

Abstract

Experiments witnessing the entanglement between two particles interacting only via the gravitational field have been proposed as a test whether gravity must be quantized. In the language of quantum information, a non-quantum gravitational force would be modeled by local operations with classical communication (LOCC), which cannot generate entanglement in an initially unentangled state. This idea is criticized as too constraining on possible alternatives to quantum gravity. We present a parametrized model for the gravitational interaction of quantum matter on a classical spacetime, inspired by the de Broglie-Bohm formulation of quantum mechanics, which results in entanglement and thereby provides an explicit counterexample to the claim that only a quantized gravitational field possesses this capability.