Schematic of the experimental setup

The setup used to detect movement driven by quantum spin. A diamond sample containing nitrogen-vacancy defects in its atomic structure (inset) is suspended above a magnet by a carbon fiber rod, which runs up through magnetic shielding to prevent interference, then through another magnet assembly to a levitating graphite plate, slotted to minimize movement caused by the magnetic array. A mirror on top of the graphite plate reflects a laser beam from an interferometer, which measures distance changes with picometer precision.