Beyond Entanglement: Diagnosing quantum mediator dynamics in gravitationally mediated experiments

TL;DR

This paper proposes using dynamical fidelity susceptibility as a sensitive method to distinguish different quantum mediator regimes in gravitationally inspired experiments, offering new ways to test quantum gravity beyond entanglement measures.

Contribution

It introduces dynamical fidelity susceptibility as a novel diagnostic tool to differentiate mediator regimes in quantum gravity experiments, extending beyond entanglement-based approaches.

Findings

Dynamical fidelity susceptibility effectively distinguishes mediator regimes.

Different regimes induce qualitatively distinct entanglement dynamics.

Provides testable signatures for optomechanical and trapped-ion platforms.

Abstract

No experimental test to date has provided conclusive evidence on the quantum nature of gravity. Recent proposals, such as the BMV experiment, suggest that generating entanglement could serve as a direct test. Motivated by these proposals, we study a system of three-harmonic oscillator system, with the mediator oscillator operating in two distinct parameter regimes: a heavy mediator regime and a light mediator regime. These regimes induce qualitatively different entanglement dynamics between the terminal oscillators. Crucially, distinguishing these regimes experimentally remains challenging when relying solely on entanglement measures. We demonstrate that the dynamical fidelity susceptibility offers a viable and sensitive probe to contrast the regimes in practice. Our results provide testable signatures for optomechanical and trapped-ion platforms simulating gravitational interactions, and provide new avenues to characterize quantum-gravity-inspired systems beyond entanglement-based protocols.