Near-field cavity optomechanics with nanomechanical oscillators

TL;DR

This paper demonstrates dispersive coupling of nanomechanical oscillators to an optical microresonator, achieving quantum-limited displacement sensitivity and observing radiation-pressure backaction, advancing room-temperature quantum optomechanics.

Contribution

It extends cavity optomechanics to nanomechanical oscillators using near-field coupling, enabling quantum-limited measurements and backaction effects at room temperature.

Findings

Achieved sub-femtometer displacement sensitivity at the standard quantum limit.

Observed radiation-pressure mediated dynamical backaction leading to coherent oscillations.

Demonstrated dispersive coupling of nanomechanical oscillators to an ultra-high finesse optical microresonator.

Abstract

Cavity-enhanced radiation pressure coupling between optical and mechanical degrees of freedom allows quantum-limited position measurements and gives rise to dynamical backaction enabling amplification and cooling of mechanical motion. Here we demonstrate purely dispersive coupling of high Q nanomechanical oscillators to an ultra-high finesse optical microresonator via its evanescent field, extending cavity optomechanics to nanomechanical oscillators. Dynamical backaction mediated by the optical dipole force is observed, leading to laser-like coherent nanomechanical oscillations solely due to radiation pressure. Moreover, sub-fm/Hz^(1/2) displacement sensitivity is achieved, with a measurement imprecision equal to the standard quantum limit (SQL), which coincides with the nanomechanical oscillator's zero-point fluctuations. The achievement of an imprecision at the SQL and radiation-pressure dynamical backaction for nanomechanical oscillators may have implications not only for detecting quantum phenomena in mechanical systems, but also for a variety of other precision experiments. Owing to the flexibility of the near-field coupling approach, it can be readily extended to a diverse set of nanomechanical oscillators and particularly provides a route to experiments where radiation pressure quantum backaction dominates at room temperature, enabling ponderomotive squeezing or QND measurements.