Ultrasensitive Force Sensing with Optically Levitated Nanoparticles

Optically levitated and cooled dielectric particles in high vacuum are a promising tool for use in precision experiments. Optically levitated particles have large quality factors by virtue of their mechanical decoupling from the environment enabling ultrasensitive force detection. We report on the trap stability at high vacuum and high intensity of as-grown and heat-treated nanospheres trapped in a new fiber-based counterpropagating trap mounted on 3D moveable piezo stages. The new trap design allows improved maneuverability of the nanoparticle, and will be used to search for deviations from Newton’s inverse square law at the micron scale with comparable sensitivity to the previous free-space version of the experiment which achieved zeptonewton sensitivity.