A circularly polarized laser beam is used to levitate and control the rotation of microspheres in high vacuum. At low pressure, rotation frequencies as high as 6 MHz are observed for birefringent vaterite spheres, limited by centrifugal stresses. Due to the extremely low damping in high vacuum, the controlled optical rotation of amorphous ${\mathrm{SiO}}_2$ spheres is also observed at rates above several MHz. At ${10}^{-7}$ mbar, a damping time of $6\times {10}^4$ s is measured for a $10\text{−}\mu \mathrm{m}$-diam ${\mathrm{SiO}}_2$ sphere. No additional damping mechanisms are observed above gas damping, indicating that even longer damping times may be possible with operation at lower pressure. The controlled optical rotation of microspheres at MHz frequencies with low damping, including for materials that are not intrinsically birefringent, provides a tool for performing precision measurements using optically levitated systems.

• Received 13 March 2018

DOI:https://doi.org/10.1103/PhysRevA.97.051802