Signatures of a gravitational quantum vacuum on dynamics of massive particles

TL;DR

This paper investigates how different definitions of position affect the dynamics of massive particles interacting with a quantized gravitational vacuum, revealing subtle observable consequences at the quantum-gravity interface.

Contribution

It compares frame-dependent and frame-independent position observables in quantum gravity, showing their distinct effects on particle dynamics and dissipation.

Findings

Frame-dependent position leads to unitary dynamics for free particles.

Frame-independent position results in dissipative behavior.

Different observables cause distinct cut-off dependences in frequency shifts.

Abstract

We study the interaction of two massive particles with a quantised gravitational field in its vacuum state using two different position observables: (i) a frame-dependent coordinate separation and (ii) a frame-independent geodesic separation. For free particles, (i) leads to purely unitary dynamics but (ii) leads to dissipation. For two particles coupled through a linear spring, (i) and (ii) lead to different cut-off dependences in the frequency shift harmonic ladder of the differential motional mode. Our findings highlight the subtle consequences of different position observables at the interface of quantum mechanics and gravity.