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Researchers from the Okinawa Institute of Science and Technology (OIST) have achieved a breakthrough by moving a levitating, centimeter-wide diamond using only the force generated by electron spin. This marks the first time a quantum effect has been observed directly manipulating an object subject to gravity. Professor Jason Twamley notes that previous attempts to test quantum mechanics on objects larger than a few tens of nanometers have failed. Their experiment involved an object eight to nine orders of magnitude more massive than prior state-of-the-art spin-mechanical experiments, setting a new baseline for studying the boundary between classical and quantum physics.

The team combined smaller devices to create their setup: a diamagnetically levitated graphite plate with a mirror connected by a carbon rod to a diamond hanging above a magnet. The diamond contains billions of nitrogen-vacancy (NV) centers, which are defects that trap unpaired electrons and act as tiny, controllable quantum magnets. By illuminating the diamond with a green laser, the researchers polarized these centers into a specific spin state. This generated tiny magnetic fluctuations that pushed the diamond down. An interferometer tracked this motion using a laser reflected off the graphite plate’s mirror to measure distance changes with picometer precision.

First author Anshuman Nayak explains that levitating macroscale objects is challenging because gravity becomes strong while quantum effects are usually weak at such scales. The OIST team approached this by starting large and working down, utilizing diamagnetic levitation similar to maglev trains. Co-author Daehee Kim highlights that NV diamonds are attractive because they can maintain quantum superposition at room temperature for longer periods than other systems. This work aims to test fundamental questions about gravity, dark matter, and whether massive objects can exist in two places at once, potentially leading to extremely accurate sensors for detecting exotic phenomena.