On the Significance of Interferometric Revivals for the Fundamental Description of Gravity

TL;DR

This paper investigates whether interferometric revivals can serve as a fundamental test of gravity's quantum nature, challenging previous claims and exploring implications for black hole physics.

Contribution

It provides a counterexample to prior claims that such signatures are exclusive to quantum channels, and discusses the fundamental implications of LOCC models of gravity.

Findings

LOCC channels can produce signatures previously thought to indicate quantum gravity

The proof by Carney et al. does not hold in certain measurement-feedback models

LOCC models of gravity have implications for black hole physics

Abstract

We show that an interaction between a harmonic oscillator and a two-level test mass (TLTM) mediated by an LOCC channel produces a signature that in [D. Carney et al., PRX Quantum 2, 030330 (2021)] is claimed to be exclusively reserved for channels that can transmit quantum information. We provide an explicit example based on a measurement-and-feedback channel, explain where the proof of Carney et al. fails, discuss to what degree setups of this type can test the nature of the gravitational interaction and remark on some fundamental implications that an LOCC model of gravity may have in black hole physics.