Ultrafast Meissner-levitated microrotor.

A Meissner-effect levitated magnetic microsphere rotor at 4.2 kelvin spins above 2.3 megahertz while maintaining an exceptionally low damping rate of 4.75 × 10 -7 hertz.

• Why it matters: Levitated mechanical systems can enable ultralow-noise sensing and tests of fundamental physics, but achieving simultaneously high rotation speed, cryogenic operation, and very low damping is challenging.
• What they did: The team demonstrated a levitated microrotor and used the linear dependence of friction on gas density to perform absolute pressure sensing across a wide cryogenic range, then used synchronized operation to detect thermal torque noise at intermediate pressure.
• The result: The rotor enabled high-accuracy absolute pressure sensing and a first preliminary narrowband search for axion-like dark matter, establishing a new precision-measurement regime for extremely weak forces and fields.

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