Researchers at the Agency for Science Technology and Research in Singapore have spun a tiny magnet at 138 million revolutions per minute, creating what may be the fastest spinning object visible to the naked eye. Tao Wang and colleagues cooled a spherical neodymium-iron-boron magnet about 30 micrometres wide to approximately -269°C within a lead superconductor trap. The magnet levitated due to the Meissner effect, which causes superconductors to expel magnetic fields. In this frictionless environment, the rotor's speed decreased by only 50 percent over 17 days. Wang noted this stability rivals Earth's rotation in terms of revolutions before significant slowdown.
The levitated magnet behaves as a sensitive sensor due to its magnetic, cold, and frictionless properties. The team tested it as a vacuum gauge at very low temperatures, which Wang says could benefit quantum computer builders who require extreme cold and isolation. Benjamin Stickler at Ulm University noted the device could precisely measure magnetic fields. Team member Andrea Vinante at the National Research Council in Italy proposed additional applications in testing fundamental physics, including searches for dark matter particle effects and detection of gravitational waves at unexplored frequencies. At very low temperatures, quantum effects dominate, making the rotor potentially useful for exploring quantum mechanics and its relationship with gravity at micrometre scales.
The findings appear in Science Advances.