Optomechanical vector sensing of new forces at 6 micron separation.

The search for new gravity-like interactions at the sub-millimeter scale is a compelling area of research, with important implications for the understanding of classical gravity and its connections with quantum physics. We report improved constraints on Yukawa-type interactions in the [Formula: see text] regime using optically levitated dielectric microspheres as test masses. The search is performed, for the first time, sensing multiple spatial components of the force vector, and with sensitivity improved by a factor of [Formula: see text] with respect to previous measurements using the same technique. The resulting upper limit on the strength of a hypothetical new force is [Formula: see text] at a Yukawa range [Formula: see text]m and close to [Formula: see text] for [Formula: see text]m. This result also advances our efforts to measure gravitational effects using micrometer-size objects, with important implications for embryonic ideas to investigate the quantum nature of gravity.