Gravity Mediated Entanglement between Oscillators as Quantum Superposition of Geometries

TL;DR

This paper investigates whether different experimental approaches to gravity-induced entanglement reveal the quantum nature of gravity, concluding that both methods are similarly valid and involve gravity in a superposition of geometries.

Contribution

The study uses a path-integral approach to analyze a setup combining superposition of delocalized states, showing both protocols are epistemologically equivalent in revealing quantum gravity features.

Findings

Both protocols are similarly relevant for understanding quantum gravity.

Entanglement arises from gravity being in a superposition of geometries.

Linearized quantum gravity predicts entanglement due to non-classical gravity states.

Abstract

Protocols for observing gravity induced entanglement typically comprise the interaction of two particles prepared either in a superposition of two discrete paths, or in a continuously delocalized (harmonic oscillator) state of motion. An important open question has been whether these two different approaches allow to draw the same conclusions on the quantum nature of gravity. To answer this question, we analyse using the path-integral approach a setup that contains both features: a superposition of two highly delocalized center of mass states. We conclude that the two usual protocols are of similar epistemological relevance. In both cases the appearance of entanglement, within linearised quantum gravity, is due to gravity being in a highly non-classical state: a superposition of distinct geometries.