Force detection with an optically levitated microsphere in vacuum*

A microsphere levitated using purely optical forces in vacuum has a high quality factor and can be used as a micro-mechanical sensor for the precise measurements of small forces such as non-Newtonian gravity in the nanoscale regime and Casimir forces [1]. In this talk, I will discuss the progress on our experiment towards the cooling of the center-of-mass motion of a dielectric microsphere trapped in an optical cavity. I will also discuss the calibration of the force sensitivity using known modulated electric fields. \\[4pt] [1] Andrew A. Geraci, Scott B. Papp, and John Kitching, Phys. Rev. Lett. 102, 101101 (2010)