Non-linear optomechanical measurement of mechanical motion

TL;DR

This paper demonstrates the first observation of non-linear mechanical motion in a micro-resonator using radiation pressure, enabling new quantum state preparations and advancing quantum measurement techniques.

Contribution

It reports the measurement of displacement-squared thermal motion via intrinsic non-linearity in cavity optomechanics, a significant step beyond linear interactions.

Findings

Observation of displacement-squared thermal motion

Generation of bimodal mechanical states below 100 pm

Potential for quantum superposition state preparation

Abstract

Precision measurement of non-linear observables is an important goal in all facets of quantum optics. This allows measurement-based non-classical state preparation, which has been applied to great success in various physical systems, and provides a route for quantum information processing with otherwise linear interactions. In cavity optomechanics much progress has been made using linear interactions and measurement, but observation of non-linear mechanical degrees-of-freedom remains outstanding. Here we report the observation of displacement-squared thermal motion of a micro-mechanical resonator by exploiting the intrinsic non-linearity of the radiation pressure interaction. Using this measurement we generate bimodal mechanical states of motion with separations and feature sizes well below 100~pm. Future improvements to this approach will allow the preparation of quantum superposition states, which can be used to experimentally explore collapse models of the wavefunction and the potential for mechanical-resonator-based quantum information and metrology applications.