Harvard physicists have detected an anomalous repulsive Casimir effect when they brought together a thin sheet of silica and a small gold-plated bead, and added a fluid, bromobenzene, creating a force of a few tens of piconewtons.

The Casimir attraction between the liquid and the silica plate is stronger than that between the gold bead and the silica, so the fluid forces its way around the bead, pushing it away from the plate.

These quantum buoyancy bearings could and lead to a new class of switchable nanoscale devices with ultra-low static friction, or to lubricate future nanomachines, or to build delicate sensors, such as a floating “nanocompass” to detect small-scale magnetic fields.