Microphotonic Forces From Superfluid Flow

TL;DR

This paper introduces a novel optical forcing method using superfluid flow and evaporation, achieving stronger forces than radiation pressure and enabling effective feedback cooling of a cryogenic microtoroid.

Contribution

It demonstrates a new superfluid-based optical force that surpasses radiation pressure and enables high-bandwidth control and cooling of mechanical resonators at cryogenic temperatures.

Findings

Optical forcing force of 1.46 nN exceeds radiation pressure by tenfold.

Microtoroid motion cooled to 137 mK using this force.

Superfluid photoconvective forces enable efficient energy transfer.

Abstract

In cavity optomechanics, radiation pressure and photothermal forces are widely utilized to cool and control micromechanical motion, with applications ranging from precision sensing and quantum information to fundamental science. Here, we realize an alternative approach to optical forcing based on superfluid flow and evaporation in response to optical heating. We demonstrate optical forcing of the motion of a cryogenic microtoroidal resonator at a level of 1.46 nN, roughly one order of magnitude larger than the radiation pressure force. We use this force to feedback cool the motion of a microtoroid mechanical mode to 137 mK. The photoconvective forces demonstrated here provide a new tool for high bandwidth control of mechanical motion in cryogenic conditions, and have the potential to allow efficient transfer of electromagnetic energy to motional kinetic energy.