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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.

To conduct this study, the team combined smaller devices: 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 acting as tiny, controllable quantum magnets. By illuminating the diamond with a green laser, researchers polarized these centers into a specific spin state, creating magnetic fluctuations that pushed the diamond down. An interferometer tracked this motion using picometer precision.

This work addresses fundamental questions about gravity and whether massive objects can exist in superposition, where they are in two places at once. First author Anshuman Nayak explains that levitating such large objects is difficult because environmental noise like heat and vibration usually disrupts quantum states. However, diamagnetic levitation allows the team to isolate the diamond effectively. Co-author Daehee Kim highlights that NV centers maintain quantum superposition at room temperature longer than other systems, making them ideal for future research into macroscopic superposition.

The findings suggest a new class of extremely accurate sensors capable of detecting dark matter and gravitational waves. Twamley concludes that while the technology is possible, scientists must refine experimental conditions to achieve quantum superposition within the regime of Einstein’s general relativity. He states they are pushing the scale from nanometers to centimeters, noting that with one more order of magnitude, researchers could finally observe a real-life version of Schrödinger’s cat.