Quantum physics is usually a story about the very small. Electrons, atoms and single particles follow quantum rules, while the objects we can see and hold follow the familiar rules of everyday physics. Bridging that gap — showing a quantum effect pushing something big enough to be influenced by gravity — has been one of the hardest experimental challenges in physics.
Researchers at the Okinawa Institute of Science and Technology (OIST) in Japan report a step across that gap, in a study published in Science Advances. They moved a levitating, centimetre-wide diamond using the force generated by electron spin alone. It is the first time a quantum effect has been observed directly manipulating an object on this scale that is subject to gravity.
The object was a diamond slab weighing 100 milligrams — about the weight of a small grain of rice, but eight to nine orders of magnitude more massive than the objects used in the best previous spin-mechanical experiments. That is a difference of hundreds of millions to billions of times.
The trick was in the diamond itself. The diamond contained billions of nitrogen-vacancy centres: tiny defects in its atomic structure that trap unpaired electrons. Those electrons act as tiny, controllable quantum magnets, through a property called spin. Spin is a quantum property of particles that behaves a little like a tiny spinning top producing a tiny magnetic field.
The team hung the diamond above a magnet, connected by a carbon-fibre rod to a levitating graphite plate. The graphite plate was fitted with a mirror, and an interferometer — an instrument that measures distance changes with picometre precision, far smaller than an atom — watched the mirror to track the diamond's movement.
Then they shone a green laser, at 50 milliwatts, onto the diamond in pulses. The laser polarised the nitrogen-vacancy centres into a predefined spin state, generating tiny magnetic fluctuations that pushed the diamond down towards the magnet. When the laser was on, the up-and-down movements were much larger than when it was off. The movement was driven by changes in spin force alone.
Professor Jason Twamley, who leads the OIST Quantum Machines Unit, said there have been many efforts to test whether quantum mechanics holds for anything larger than a few tens of nanometres, so far without success. The new result, he said, shows a classical mechanical response to a quantum force on an object far more massive than before.
Why try this at all? One reason is a deep question: is gravity itself quantum, or entirely classical? To test that, physicists ultimately need to put objects with large enough masses into quantum superposition — the strange state in which a particle exists in distinctly different places at once until measured — while they are levitated in a vacuum, away from noise. Starting small and working up has proved very hard. The OIST team went the other way: start with a large object that can be levitated, and look for quantum effects in it.
The team is clear that this is a platform for future tests, not yet the famous "Schrödinger's cat" experiment. Twamley said they have shown a large classical response from a small quantum effect, and the question now is how to refine the experiment to reach quantum superposition in the regime where gravity matters. Along the way, the same techniques could lead to extremely precise sensors for detecting dark matter, gravitational waves and other exotic phenomena.
For GCSE physics, the helpful picture is this: forces do not have to be big to be real, and "quantum" does not mean "invisible for ever". A laser, a magnet, a diamond and a mirror precise enough to notice movements smaller than an atom were enough to make a quantum push visible. That is a good reminder that in physics, measuring carefully is often just as important as the idea itself.
If physics sometimes feels abstract, a first lesson in physics can make ideas like spin, forces and measurement concrete — starting from what can be seen and measured, and building up to the questions scientists are still trying to answer, with booster and mock-exam help in physics along the way. Book your first lesson
Sources:
- Okinawa Institute of Science and Technology / Phys.org, "First observation of quantum spins shifting a centimeter-scale object in the lab", 7 October 2026: https://phys.org/news/2026-10-quantum-shifting-centimeter-scale-lab.pdf
- Nayak, A., et al., "Spin-force from a Nitrogen-Vacancy ensemble drives a 100 mg levitated resonator", Science Advances (2026), DOI: 10.1126/sciadv.aeh0566: https://www.science.org/doi/10.1126/sciadv.aeh0566