On the possibility of laboratory evidence for quantum superposition of geometries

TL;DR

This paper discusses the potential for laboratory experiments to provide evidence of quantum superpositions of spacetime geometries through gravitationally entangled particles, offering a covariant description and addressing previous objections.

Contribution

It provides a covariant framework for understanding quantum superpositions of spacetime and argues that laboratory measurements could confirm such phenomena.

Findings

Quantum superposition of proper times can be measured experimentally.

The proposed effect offers evidence for quantum superpositions of spacetime geometries.

The effect relates to the Planck mass and is likely a real physical phenomenon.

Abstract

We analyze the recent proposal of measuring a quantum gravity phenomenon in the lab by entangling two particles gravitationally. We give a generally covariant description of this phenomenon, where the relevant effect turns out to be a quantum superposition of proper times. We point out that measurement of this effect would count as evidence for quantum superposition of spacetime geometries. This interpretation addresses objections appeared in the literature. We observe that the effect sheds light on the Planck mass, and argue that it is very plausibly a real effect.