5D cooling and torque detection with optically levitated nanoparticles

Abstract

An optically levitated nonspherical particle in a vacuum is great for torque sensing and rotational quantum mechanics. Recently, we optically levitated silica nanodumbbells in a vacuum and drove them to rotate beyond 5 GHz. With an optically levitated nanorotor, we demonstrated a torque sensor with a record-high sensitivity [Nature Nanotechnology, 15, 89 (2020)]. Such an ultrasensitive torque sensor will have the potential to detect the long-sought quantum vacuum friction. We also demonstrated 5D cooling and observed nonlinear dynamics of an optically levitated nanodumbbell in a vacuum. This work is an important step towards full quantum control of the rigid-body motion of a levitated nonspherical particle.