Optomechanical feedback cooling of a 5 mm-long torsional mode

TL;DR

This paper demonstrates significant optical feedback cooling of a large-scale torsional nanofiber mode, enabling advanced control of macroscopic mechanical systems with potential quantum applications.

Contribution

It introduces a novel feedback cooling technique for a 5 mm-long torsional mode using polarization-based optomechanical coupling.

Findings

Achieved three orders of magnitude cooling of torsional mode

Demonstrated polarization-based feedback control

Potential for quantum state studies of macroscopic objects

Abstract

We report three orders of magnitude optical cooling of the fundamental torsional mode of a 5 mm-long, 550 nm diameter optical nanofiber. The rotation of the nanofiber couples to the polarization of guided laser fields. We use a weak laser probe to monitor the rotation, and use feedback to modulate the polarization of an auxiliary drive laser providing torque. Our results present a tool for the optomechanical control of large-scale torsional resonators, with metrological applications and potential implications for studying macroscopic objects in quantum states.