Laser-induced rotation and cooling of a trapped microgyroscope in vacuum

Abstract

Quantum state preparation of mesoscopic objects is a powerful playground for the elucidation of many physical principles. The field of cavity optomechanics aims to create these states through laser cooling and by minimizing state decoherence. Here we demonstrate simultaneous optical trapping and rotation of a birefringent microparticle in vacuum using a circularly polarized trapping laser beam—a microgyroscope. We show stable rotation rates up to 5 MHz. Coupling between the rotational and translational degrees of freedom of the trapped microgyroscope leads to the observation of positional stabilization in effect cooling the particle to 40 K. We attribute this cooling to the interaction between the gyroscopic directional stabilization and the optical trapping field.

Polarization-dependent optomechanics mediated by chiral microresonators

“…Chirality-controlled optical trapping and manipulation can be exploited to address novel strategies for optomechanics experiments and optical sorting 49 . Furthermore, spin-dependent optical forces pave the way to novel methodologies for optical cooling and trapping based on the coupling of translational and rotational degrees of freedom towards the quantum mechanical motional ground states of levitated particles 12,[50][51][52] . For L-chiral microparticles, the centre-of-mass and rotations could be actively laser cooled in a s þ s þ counter-propagating beams configuration.…”

“…The interaction of chiral light with achiral objects has received much interest in the field of optical trapping and manipulation, leading to a high level of optomechanical control and detection at the micro and nanoscale [9][10][11][12][13] . The observation that light can transfer spin angular momentum (SAM) to matter dates back to the pioneering work by Beth 14 in 1936, who demonstrated that CP light exerts a torque on a birefringent wave plate.…”

“…The development of optical tweezers 15 (OT) stimulated the exploitation of optical forces and torques in several diverse areas such as biophysics 16 , nanotechnology 13 , complex fluids [17][18][19][20][21] , microrheology 10,11 and microfluidics 22,23 . In particular, several methods have been used to induce optically controlled rotations and alignment: anisotropic scattering due to particle shape 24,25 , form birefringence of anisotropic objects [26][27][28] , optical birefringence 9,12,29 and transfer of angular momentum (AM) from laser beams carrying SAM and/or orbital angular momentum 12,30,31 . In optical manipulation experiments, the radiation forces and torques exerted by a CP beam are generally decoupled.…”

Generating stable tractor beams with dielectric metasurfaces

“…This would allow for the arbitrary manipulation and sorting of small particles with a single beam. Furthermore, these beams may prove particularly useful for exploring new physical phenomena since they can stably pull particles through vacuum [47,48].…”

Helicity-dependent three-dimensional optical trapping of chiral microparticles

“…Noteworthy, neither the spin angular momentum carried by circularly polarized beams nor the orbital angular momentum carried by Laguerre-Gaussian beams are usually considered as basic ingredients for optical trapping. Indeed, the angular momentum of light has been merely used so far as a tool for addressing the rotational degrees of freedom of optically trapped transparent or absorbing objects, which may be set into spinning and/or orbiting motions [5][6][7][8][9][10] .…”