https://phys.org/news/2018-07-world-fastest-rotation.html

It takes considerable technical effort to make on object rotate that fast. "To do so, we trap the glass particle in a vacuum apparatus using so-called optical tweezers," explains René Reimann, a post-doc in Novotny's laboratory. Optical tweezers are created by a strongly focused laser beam, where the glass particle is levitated by light forces at the focus of the beam. This allows the scientists to eliminate any direct mechanical contact with the outside world, which would lead to friction losses. Moreover, the pressure in the apparatus is a hundred million times lower than the normal air pressure at sea level. This means that only very rarely do single air molecules collide with the particle, slowing it down slightly in the process.

The researchers now adjust the polarisation of the laser beam to be circular. This means that the direction in which the electric field of the laser light oscillates is not constant, as it would be for linear polarization, but rather rotates continuously. That rotation, in turn, is partially taken over by the glass particle when the laser light passes through it. The torque thus transferred makes the nanoparticle turn faster and faster.