Three dimensional cooling and detecting of a nanosphere with a single cavity

We propose an experimental scheme to cool and measure the three-dimensional (3D) motion of an optically trapped nanosphere in a cavity. Driven by three lasers on TEM00, TEM01, and TEM10 modes, a single cavity can cool a trapped nanosphere to the quantum ground states in all three dimensions under the resolved-sideband condition. Our scheme can also detect an individual collision between a single molecule and a cooled nanosphere efficiently. Such ability can be used to measure the mass of molecules and the surface temperature of the nanosphere. We also discuss the heating induced by the intensity fluctuation, pointing instability, and the phase noise of lasers, and justify the feasibility of our scheme under current experimental conditions.