A tiny magnet suspended above a superconductor has been tested as a pressure sensor in a cold vacuum. Its rotation reached 138 million revolutions per minute. Gas molecules slowed the magnet, giving researchers a way to measure pressure where low temperatures make conventional sensing difficult. The laboratory experiment has now appeared in a peer-reviewed journal.
A laboratory experiment has turned a freely suspended micromagnet into a gauge for pressure at extremely low temperatures. Cooling lead until it becomes superconducting lets it repel the magnet through the Meissner effect, the exclusion of magnetic fields. This supports the rotor without a bearing touching it. A magnetic drive then keeps its rotation synchronized with an applied field.[1]
The authors report reaching 138 million turns per minute at a temperature of 4.2 kelvin. The pressure measurement uses the subsequent loss of rotational speed: molecules of residual gas strike the magnet and exert drag. Following this decay provides information about gas inside the cold chamber. Such measurements matter for experiments whose delicate mechanical motion is disturbed by collisions with gas.[1]
The work has appeared in the peer-reviewed journal Science Advances; an author preprint was first shared in September 2025. New Scientist reported the experiment on 6 November. The researchers also discuss magnetic sensing and fundamental-physics uses. Those remain proposed extensions of the platform. Interpreting very low pressures still requires accounting for energy losses beyond gas drag, even with contact-free support.[1]
