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.
Highlights
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
In particular, optical forces enable cooling and control of microscale mechanical oscillators that can be used for ultrasensitive detection of forces, fields and mass [7,8,9], quantum and classical information systems [10], and fundamental science [11,12]
We demonstrate an alternative photoconvective approach to optical forcing that allows an order-ofmagnitude stronger mechanical actuation than radiation pressure. This technique utilizes the convection in superfluids, whereby frictionless fluid flow is generated in response to a local heat source
Summary
We demonstrate an alternative photoconvective approach to optical forcing that allows an order-ofmagnitude stronger mechanical actuation than radiation pressure In our implementation, this technique utilizes the convection in superfluids, whereby frictionless fluid flow is generated in response to a local heat source. Due to the presence of superflow, superfluid helium-4 has the largest thermal conductivity of any known material This could be used to greatly reduce localized heating of the mechanical element, which often constrains the performance of cryogenic quantum optomechanics experiments [32]. Since the superfluid flow can be generated in a location remote from the mechanical element, superfluid photoconvective forces offer the prospects for remote actuation, a capability that is not available with any cryogenic actuation technique and could be used, for instance, to apply torques at microscale
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