Suspended animation - testing Newtonian gravity at the micron scale*

An active experimental front in the modern study of Gravity is testing the (Newtonian) law of gravitation at the 1 μm – 100 μm length scale. Electromagnetic forces are several orders of magnitude stronger than gravity, and pose a formidable challenge in any experiment aiming to measure the latter. This work describes results from a platform based on optically trapped neutral microspheres that probes deviations from Newtonian gravity. In addition to modest improvements to a previous iteration of the experimental apparatus, we present a novel technique that allows further suppression of electromagnetic backgrounds. This technique, which relies an optomechanical force sensor, provides a complementary technique to previous searches that have largely relied on variations of mechanical springs.