Full rotational control of levitated silicon nanorods

Abstract

Optically levitated nano-objects in vacuum are amongst the highest-quality mechanical oscillators, and thus of great interest for force sensing, cavity quantum optomechanics, and nanothermodynamic studies. These precision applications require exquisite control. Here, we present full control over the rotational and translational dynamics of an optically levitated silicon nanorod. We trap its centre-ofmass and align it along the linear polarization of the laser field. The rod can be set into rotation at a predefined frequency by exploiting the radiation pressure exerted by elliptically polarized light. The rotational motion of the rod dynamically modifies the optical potential, which allows tuning of the rotational frequency over hundreds of Kilohertz. Through nanofabrication, we can tailor all of the trapping frequencies and the optical torque, achieving reproducible dynamics which are stable over months, and analytically predict the motion with great accuracy. This first demonstration of full ro-translational control of nanoparticles in vacuum opens up the fields of rotational optomechanics, rotational ground state cooling and the study of rotational thermodynamics in the underdamped regime.

Recent Progress in Optical‐Resonance‐Assisted Movement Control of Nanomotors

“…Copyright 2016, American Chemical Society. d−g) Si rotary nanomotors in vacuum driven by circularly polarized laser light . An individual Si nanorod motor is trapped in vacuum by the standing light wave formed by two counterpropagating 1550 nm laser beams (d).…”

“…An individual Si nanorod motor is trapped in vacuum by the standing light wave formed by two counterpropagating 1550 nm laser beams (d). The rotational frequency of the nanomotor is modulated by the e) laser power as well as f) the pressure in the vacuum chamber . Usually the distribution of the rotational frequency is broad because the collision between the nanomotor and the gas molecules pushes the nanomotor to regions of different light intensities.…”

“…g) The rotation frequency stability can be improved by periodically switching the laser polarization between linear and circular . (d−f) Reproduced with permission . Copyright 2017, Optical Society of America.…”

Cavity optomechanics in a levitated helium drop

“…The rotational motion of a levitated liquid differs from that of a levitated solid (described in Refs. [68][69][70][71][72][73][74][75]) in several important respects. These include the liquid's electromagnetic and mechanical isotropy (which should more closely approximate free rotation),the independence between the liquid's external shape and its rotation, and, in the case of superfluid 4 He, dissipationless nonrigid body rotational motion.…”

Bistability and squeezing of the librational mode of an optically trapped nanoparticle

“…In Ref. [31,32], the directions of the optically levitated dielectric nanoparticles were fixed, and the librational(torsional) optomechanics of a Levitated Nonspherical Nanoparticle was reported. In these experiments, the torsional mode of an ellipsoidal nanoparticle levitated by a linearly polarized Gaussian beam was experimentally observed, and the scheme of sideband cooling torsional mode was proposed [31].…”