Quantum correlations of light due to a room temperature mechanical oscillator for force metrology

TL;DR

This paper demonstrates the detection of quantum correlations in light caused by a room temperature nanomechanical oscillator, enabling quantum-enhanced force measurement at ambient conditions.

Contribution

It shows room temperature quantum correlations in optomechanical systems using a novel measurement approach, expanding quantum metrology applications beyond cryogenic environments.

Findings

Quantum correlations detected at room temperature.

Enhanced force estimation using quantum correlations.

Effective measurement of quantum back-action force.

Abstract

The coupling of laser light to a mechanical oscillator via radiation pressure leads to the emergence of quantum mechanical correlations between the amplitude and phase quadrature of the laser beam. These correlations form a generic non-classical resource which can be employed for quantum-enhanced force metrology, and give rise to ponderomotive squeezing in the limit of strong correlations. To date, this resource has only been observed in a handful of cryogenic cavity optomechanical experiments. Here, we demonstrate the ability to efficiently resolve optomechanical quantum correlations imprinted on an optical laser field interacting with a room temperature nanomechanical oscillator. Direct measurement of the optical field in a detuned homodyne detector ("variational measurement") at frequencies far from the resonance frequency of the oscillator reveal quantum correlations at the few percent level. We demonstrate how the absolute visibility of these correlations can be used for a quantum-enhanced estimation of the quantum back-action force acting on the oscillator, and provides for an enhancement in the relative signal-to-noise ratio for the estimation of an off-resonant external force, even at room temperature.