Scanning force sensing at $\mu$m-distances from a conductive surface with nanospheres in an optical lattice

Understand

The center-of-mass motion of optically trapped dielectric nanoparticles in vacuum is extremely well-decoupled from its environment, making a powerful tool for measurements of feeble sub-attonewton forces.

• We demonstrate a method to trap and manuever nanoparticles in an optical standing wave potential formed by retro-reflecting a laser beam from a metallic mirror surface.
• We can reliably position a $\sim 170$ nm diameter silica nanoparticle at distances of a few hundred nanometers to tens of microns from the surface of a gold-coated silicon mirror by transferring it from a single-beam tweezer trap into the standing wave potential.
• We can further scan the two dimensional space parallel to the mirror surface by using a piezo-driven mirror.