Quantum Spin Just Moved a Diamond You Can See

A diamond you could see with your naked eye just got pushed around by quantum physics. Researchers at the Okinawa Institute of Science and Technology in Japan have used quantum spin — the tiny built-in magnetism carried by electrons — to physically move a levitating diamond about a centimeter wide. It is the first time a quantum effect has been observed directly moving an object large enough for gravity to matter, according to a report from phys.org on the study, published this month in the journal Science Advances.

The result matters because quantum mechanics and gravity have never quite agreed. Quantum effects power lasers, MRI scanners, semiconductors and quantum computers, yet they have almost always been demonstrated on atoms and other nanoscopic particles, far removed from human senses. Gravity, meanwhile, rules the classical world described by Einstein's general relativity — but its effects are vanishingly weak at the tiny scales where quantum phenomena show up. Bridging the two has been one of physics' longest-running problems, and big objects are brutally hard to isolate from heat and vibration, which is why every previous success stayed microscopic. The new work attacks the problem from the other end: instead of scaling tiny objects up, the team started with something visible and detected the quantum spin force acting on it.

Quantum Spin, a Green Laser and a Floating Diamond

The experiment reads like a magic trick with very expensive props. At its heart sits a diamond packed with billions of nitrogen-vacancy centers — atomic defects that trap unpaired electrons and act as tiny, controllable quantum magnets. The team hung the diamond from a carbon rod above a magnet and connected it to a graphite plate that levitates over a checkerboard of magnets, the same diamagnetic trick that lifts maglev trains. Then they fired pulses of green laser light at the diamond, flipping the trapped electrons into a chosen quantum spin state. Each flip generated a tiny magnetic fluctuation, and together billions of them produced a measurable push, nudging the diamond downward against gravity.

Detecting that nudge took its own feat of engineering. A mirror on top of the levitating graphite plate reflected a laser beam from an interferometer, which measured distance changes with picometer precision — far smaller than an atom. The researchers ran the experiment in pulses, comparing the diamond's movement with the laser on and off, and found the quantum spin driven motion clearly larger than the background drift. As first author Anshuman Nayak, a doctoral student in the lab, explained in the phys.org report, most teams try to levitate ever-smaller objects and scale up; his group went the opposite direction, starting large and working down, because levitating big objects with conventional techniques had proved extremely difficult.

The choice of diamond was deliberate. According to co-author Daehee Kim, another doctoral student on the team, nitrogen-vacancy centers are well understood, easy to control and keep their quantum behavior at room temperature longer than most competing systems — qualities that make them attractive for pushing toward even larger quantum spin effects in future experiments.

A Billion Times Bigger Than the Previous Record

The scale of the jump is what has physicists talking. The levitating resonator weighed about a hundred milligrams, and the object it moved was eight to nine orders of magnitude more massive than anything shifted by quantum spin forces before — roughly a billion times heavier, as reported by scienmag. Professor Jason Twamley, who leads the Quantum Machines Unit at the institute, put it plainly: his team has shown a large classical response to a small quantum effect. Until now, efforts to test whether quantum mechanics holds for anything larger than a few tens of nanometers had come up empty.

That boundary — between the quantum world of the very small and the classical world of everything else — is exactly what the experiment is built to probe. Einstein spent the last decades of his life wrestling with the same questions the result touches: is gravity itself quantum, can an object with mass really be in two places at once, and what happens to information inside a black hole? The diamond did not answer any of those, but it created the first experimental platform that might eventually get close.

What a Floating Diamond Could Become

The near-term payoff is likely to be sensors. The team says the setup opens the way to a new class of extremely precise instruments that could detect dark matter, gravitational waves and other exotic phenomena — measurements that demand exactly the kind of isolation from noise this experiment achieved. A device that can feel the push of quantum spin on a visible object is, in effect, a force detector of extraordinary sensitivity, and the researchers are already developing it in that direction.

The longer-term prize is stranger. Twamley says the group is pushing the bar from nanometers to centimeters, and with one more order of magnitude they could finally observe a real macroscopic quantum superposition — the famous Schrödinger's cat scenario, an object with mass existing in two states at once, inside the regime where Einstein's gravity applies. That is still a formidable engineering challenge: the current result is a classical mechanical response to a quantum force, not superposition itself, and every step up in mass multiplies the battle against environmental noise. But the question is no longer whether such technology is possible. It is how fast the team can refine it — and what the universe looks like when they do. For the bigger picture, read our explainer on the 2026 Nobel Prize science winners or browse the Science topic page for new research as it lands.