Enhanced Gravitational Entanglement via Modulated Optomechanics

TL;DR

This paper demonstrates that modulating optomechanical coupling can significantly enhance gravity-mediated entanglement between systems, but decoherence effects and measurement constraints pose substantial challenges for experimental realization.

Contribution

It introduces a method to increase gravitational entanglement via optomechanical modulation and analyzes the associated decoherence and measurement limitations.

Findings

Modulation can boost entanglement rates by several orders of magnitude.

Decoherence effects increase proportionally with entanglement improvements.

Measurement sensitivity requirements are comparable for entanglement verification and superposition probing.

Abstract

The role of entanglement in determining the non-classicality of a given interaction has gained significant traction over the last few years. In particular, as the basis for new experimental proposals to test the quantum nature of the gravitational field. Here we show that the rate of gravity mediated entanglement between two otherwise isolated optomechanical systems can be significantly increased by modulating the optomechanical coupling. This is most pronounced for low mass, high frequency systems - convenient for reaching the quantum regime - and can lead to improvements of several orders of magnitude, as well as a broadening of the measurement window. Nevertheless, significant obstacles still remain. In particular, we find that modulations increase decoherence effects at the same rate as the entanglement improvements. This adds to the growing evidence that the constraint on noise (acting on the position d.o.f) depends only on the particle mass, separation, and temperature of the environment and cannot be improved by novel quantum control. Finally, we highlight the close connection between the observation of quantum correlations and the limits of measurement precision derived via the Cram\'er-Rao Bound. An immediate consequence is that probing superpositions of the gravitational field places similar demands on detector sensitivity as entanglement verification.