Optical cooling of the torsional modes of a tapered nanofiber

Optical nanofibers (ONFs) are optical fibers which have been heated and pulled to produce a tapered region with a diameter in the hundreds of nanometers. They have provided a robust platform for strong interactions between light and atoms. More recently, studies have investigated the torsional motion of an ONF's tapered region. These torsional modes have been shown to have quality factors over 10⁵ and so their potential to demonstrate quantum effects is possible, although difficult. Here we investigate sideband cooling the torsional mode and cooling by direct optical feedback. This work hopes to guide research into the suppression of torsional motion, which is understood to be a heating source for atoms trapped around the ONF.