The fastest levitated spinning magnet ever made might help physicists search for dark matter
Tiny levitated magnets are able to avoid contact friction, making them useful for detecting extremely weak forces and magnetic fields and acting as ultralow-noise quantum sensors and precision measurement tools. Combining levitation with extreme cold further reduces unwanted motion that can make faint signals hard to detect.
Scientists have created the world's fastest levitated spinning magnet, a micromagnet that reached an astonishing 2.3 million revolutions per second. This groundbreaking achievement, reported in Science Advances, could pave the way for new discoveries in physics, particularly in the search for dark matter particles.
The researchers utilized a superconducting lead trap cooled with liquid helium to levitate magnetic spheres with a radius of around 30 micrometers. By employing magnetic coils, they accelerated these spheres to an unprecedented rotational speed of 2.3 million revolutions per second, surpassing the previous record of 38 million revolutions per minute.
Operating at a temperature of approximately 4.2 Kelvin (around -269°C), the researchers observed an incredibly slow decay time of about 24 days for the magnet's rotation. This low damping rate is the lowest ever measured in a levitated micro or nanosized object. The spinning rotor also demonstrated remarkable pressure sensing capabilities, measuring down to 10⁻⁸ mbar, which is lower than any previously reported spinning rotor gauge temperature.
Furthermore, the spinning magnet was used to search for axion-like dark matter particles, hypothetical candidates for cold dark matter. While the preliminary search did not yield any relevant signatures, it did help to establish upper limits on how strongly these particles could interact with electrons. The study authors noted that their findings are preliminary and that a more thorough search would require future experiments with larger coupling and lower dissipation.
Beyond its potential role in dark matter research, the ultrafast spinning magnet could also be used for pressure sensing in extreme cold vacuum chambers, precision rotation, gravity sensors, and tests of materials under extreme mechanical stress. The authors suggested that this technology could have broad applications in fundamental physics, including the detection of high-frequency gravitational waves, testing spontaneous collapse models of gravity, and probing the quantumness versus classicality of gravity.
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