Dynamical Backaction of Microwave Fields on a Nanomechanical Oscillator

TL;DR

This paper demonstrates how microwave fields can exert dynamical backaction on a nanomechanical oscillator, achieving significant cooling and strong coupling in a superconducting microwave cavity system.

Contribution

It reports the first measurement of radiation-pressure backaction cooling of a high-Q nanomechanical oscillator in the resolved-sideband regime.

Findings

Mechanical mode cooled by a factor of 5 below thermal equilibrium

Achieved phonon occupancy of 140 quanta

Strong microwave-mechanical coupling observed

Abstract

We measure the response and thermal motion of a high-Q nanomechanical oscillator coupled to a superconducting microwave cavity in the resolved-sideband regime where the oscillator's resonance frequency exceeds the cavity's linewidth. The coupling between the microwave field and mechanical motion is strong enough for radiation pressure to overwhelm the intrinsic mechanical damping. This radiation-pressure damping cools the fundamental mechanical mode by a factor of 5 below the thermal equilibrium temperature in a dilution refrigerator to a phonon occupancy of 140 quanta.