Spinning micromagnet demonstrates pressure sensing at 4.2 Kelvin

Researchers demonstrated a levitated spinning micromagnet as a pressure sensor at 4.2 Kelvin, extending a measurement method whose previously reported lowest operating temperature was 77 Kelvin. The Science Advances study operated the sensor at pressures down to 10⁻⁸ mbar. The team suspended magnetic spheres in a superconducting lead trap and used magnetic coils to accelerate them to 2.3 million revolutions per second. Their measured slowdown implied a characteristic speed-decay time of about 24 days. The pressure measurements could help characterize cold vacuum environments used in quantum technologies. A separate preliminary dark-matter search covered only a very narrow frequency range and found no related signatures.