At the Okinawa Institute of Science and Technology (OIST), a team of researchers has achieved what sounds like science fiction – a levitating disk that floats effortlessly above magnets, entirely without external power.
The OIST team’s achievement centers on a macroscopic, virtually frictionless levitating disk, which resists magnetic eddy forces that typically interfere with sensitivity. The researchers believe this breakthrough could revolutionize sensors designed to detect incredibly small forces, including those linked to dark energy, dark matter, and quantum-scale interactions.
According to the team, microscale devices are “highly sensitive” to environmental variations, making them unreliable for precision experiments. In contrast, their macroscale magnetic levitation system operates at room temperature and is “simpler and much more resistant to the environment.” Because it naturally responds to gravity, it’s well-suited for experiments at the crossroads of quantum and classical physics.
However, magnetic levitation at large scales faces a long-standing obstacle, eddy-current damping. These currents, formed when conductive materials move through magnetic fields, can create unwanted friction. While such effects are useful in technologies like bullet train brakes, the researchers explain, “this friction is problematic” for precision measurement.
“This is particularly useful in the case of rotors,” they note, “as their torque and angular momentum… can be strongly influenced by friction. Freely suspending the rotor could drastically reduce these disturbances.”
In earlier experiments, the OIST team attempted to minimize these effects by constructing a levitating square plate from graphite powder coated with silica and embedded in wax. The wax confined the eddy currents to microscopic regions, reducing interference and paving the way for highly sensitive accelerometers capable of detecting minuscule gravitational changes. One such prototype, the researchers revealed, was even launched into space as a proof of concept to explore dark matter interactions and gravitational waves.
Yet, this wax-based design had drawbacks. The researchers found it weakened the system’s levitation strength, making it unsuitable for applications that required additional weight “such as from a mirror used to track its rotation.”
Determined to improve their design, the team turned to pure graphite, removing the wax entirely. This new disk not only preserved its powerful lift but also “does away with eddy-current damping entirely in an ideal system.”
Professor Jason Twamley, head of the research unit, explained that the rotor’s symmetry plays a critical role: “A rotor remains in the same magnetic field when rotating around its central axis above magnets. It does not experience a change in flux – and this therefore eliminates eddy-current damping.”
The OIST scientists confirmed their theoretical model through simulations before constructing a real-world prototype using only three rare-earth magnets and the graphite disk. Despite its simplicity, the setup demonstrated stable, sustained levitation all without external energy.
With success in hand, the researchers are now refining their design through precision machining and vacuum testing to reduce air friction and enhance stability. Twamley envisions that their levitating disk could serve as an exceptionally precise gyroscope or as a cooled, ultra-sensitive system capable of probing the quantum regime:
“It can be spun up to serve as precise and reliable gyroscopes or spun down – cooled – into the quantum regime.”
First author and PhD student Daehee Kim highlighted the system’s simplicity, noting that with only a one-centimeter graphite disk and a few rare-earth magnets, they were able to design a “diamagnetically levitating rotor” that entirely avoids eddy-current losses. Kim added,
“If we can slow its rotation enough, its motion will enter the quantum regime, which could open up an entirely new platform for quantum research.”