6  GHz hyperfast rotation of an optically levitated nanoparticle in vacuum

Abstract

We report an experimental observation of a record-breaking ultrahigh rotation frequency about 6 GHz in an optically levitated nanoparticle system. We optically trap a nanoparticle in the gravity direction with a high numerical aperture (NA) objective lens, which shows significant advantages in compensating the influences of the scattering force and the photophoretic force on the trap, especially at intermediate pressure (about 100 Pa). This allows us to trap a nanoparticle from atmospheric to low pressure ( 10 − 3 Pa ) without using feedback cooling. We measure a highest rotation frequency about 4.3 GHz of the trapped nanoparticle without feedback cooling and a 6 GHz rotation with feedback cooling, which is the fastest mechanical rotation ever reported to date. Our work provides useful guides for efficiently observing hyperfast rotation in the optical levitation system and may find various applications such as in ultra-sensitive torque detection, probing vacuum friction, and testing unconventional decoherence theories.

Surface-induced decoherence and heating of charged particles

“…which is equivalent to (51) for negligible damping γ m = 0 in the bulk. Like in (50), the superconductor acts like a mirror for the fluctuations generated in the dielectric layer.…”

“…For instance, the rotation states of molecular ions have been proposed for quantum information processing [7,8,10,12,13,39,40], promising significant advantages in comparison to harmonic degrees of freedom due to the special topology of rotations in three dimensions [11]. At the same time, experiments with levitated nanorotors [41][42][43][44][45][46][47][48][49][50][51] reach millikelvin rotational temperatures [48,50,52], pointing the path towards ultra-precise torque sensors [41,43,44,46,47,49,51,53], the search for new physics [54], and tests of the quantum superposition principle with massive objects [52,[55][56][57][58].…”

Cooling the optical-spin driven limit cycle oscillations of a levitated gyroscope

“…A beam of such polarisation can stably trap and continuously rotate mesoscopic particles: by reducing the ambient pressure in a levitated geometry in vacuum, extraordinarily high spin rates may be available when operating micron-sized birefringent particles in vacuum [4]. By extending to smaller particles, rotation rates of several GHz have recently been demonstrated [5][6][7][8]. These achievements provide unprecedented access to a relatively unexplored physical regime.…”

Imaging the dipole scattering of an optically levitated dielectric nanoparticle

“…Recently, the temperature of the CoM motion of a nanoparticle has been cooled to the quantum ground state 18 , which can be used to research macroscopic quantum phenomenon such as the Schrodinger's cat state [19][20][21] . Moreover, the optically levitated nanoparticle systems have been studied for measuring the Casimir force and torque 22,23 , and GHz scale rotation was recently observed 22,[24][25][26] , including the record-breaking ultrahigh rotation frequency of about 6 GHz by our group 26 .…”