Optomechanical measurement of a millimeter-sized mechanical oscillator near the quantum limit

TL;DR

This paper demonstrates near-quantum limited optomechanical measurements on a millimeter-sized quartz oscillator, revealing quantum behavior in a macroscopic system and enabling future macroscopic quantum experiments.

Contribution

It introduces a novel macroscopic optomechanical system coupling a quartz disk to a charge qubit, achieving near-quantum limited measurements in a large mechanical oscillator.

Findings

Measured thermal motion down to 35 mK, near the quantum ground state.

Achieved effective radiation-pressure interaction in a 20mg oscillator.

Opened pathways for macroscopic quantum experiments.

Abstract

Cavity optomechanics is a tool to study the interaction between light and micromechanical motion. Here we observe near-quantum limited optomechanical physics in a truly macroscopic oscillator. As the mechanical system, we use a mm-sized piezoelectric quartz disk oscillator. Its motion is coupled to a charge qubit which translates the piezo-induced charge into an effective radiation-pressure interaction between the disk and a microwave cavity. We measure the thermal motion of the lowest mechanical shear mode at 7MHz down to 35 mK, corresponding to roughly 100 quanta in a 20mg oscillator. The work opens up opportunities for macroscopic quantum experiments.