Uploaded November 2025 | Updated September 2026, 1 week ago
Movie 1. Rotating disk on the checkerboard magnetic array. A nitrogen gas flow is used to apply torque to the levitated pyrolytic graphite disk. Due to the strong axial symmetry, the rotation rapidly decays. Additionally, librational trapping of the disk is observed- an effect that would be absent in a perfectly symmetric disk.
Movie 2. Rotating disk on the axially symmetric magnetic array. Unlike in Video 1, the disk maintains rotation with minimal damping, even at atmospheric pressure, due to the improved axial symmetry of the magnetic trap.
Movie 3. Side view of the rotating disk on the axially symmetric magnetic array. Slight wobbling is observed.
Abstract
Levitation of macroscopic objects in a vacuum is a key step towards the development of high-precision inertial sensors and pressure sensors, as well as towards the fundamental studies of quantum mechanics and its relation to gravity. Diamagnetic levitation offers a passive method at room temperature to isolate macroscopic objects in vacuum environments, yet eddy current damping remains a critical limitation for electrically conductive materials. We show that there are situations where the motion of conductors in magnetic fields does not, in principle, produce eddy damping, and demonstrate an electrically conducting rotor diamagnetically levitated in an axially symmetric magnetic field in high vacuum. Experimental measurements and finite-element simulations reveal gas collision damping as the dominant loss mechanism at high pressures, while residual eddy damping, which arises from symmetry-breaking factors such as platform tilt or material imperfections, dominates at low pressures. The conclusion is supported by an analytic proof and an analytic example of zero steady current density for a rotating conductor in an axially symmetric magnetic field. This demonstrates a macroscopic levitated rotor with extremely low rotational damping and paves the way to fully suppress rotor damping, enabling ultra-low-loss rotors for gyroscopes, pressure sensing, and fundamental physics tests.
Kim, D., Tian, S., Calderoni, B. et al. A magnetically levitated conducting rotor with ultra-low rotational damping circumventing eddy loss. Commun Phys 8, 381 (2025). doi.org/10.1038/s42005-025-02318-4
Movie 1. Rotating disk on the checkerboard magnetic array. A nitrogen gas flow is used to apply torque to the levitated pyrolytic graphite disk. Due to the strong axial symmetry, the rotation rapidly decays. Additionally, librational trapping of the disk is observed- an effect that would be absent in a perfectly symmetric disk.
Movie 2. Rotating disk on the axially symmetric magnetic array. Unlike in Video 1, the disk maintains rotation with minimal damping, even at atmospheric pressure, due to the improved axial symmetry of the magnetic trap.
Movie 3. Side view of the rotating disk on the axially symmetric magnetic array. Slight wobbling is observed.
Abstract
Levitation of macroscopic objects in a vacuum is a key step towards the development of high-precision inertial sensors and pressure sensors, as well as towards the fundamental studies of quantum mechanics and its relation to gravity. Diamagnetic levitation offers a passive method at room temperature to isolate macroscopic objects in vacuum environments, yet eddy current damping remains a critical limitation for electrically conductive materials. We show that there are situations where the motion of conductors in magnetic fields does not, in principle, produce eddy damping, and demonstrate an electrically conducting rotor diamagnetically levitated in an axially symmetric magnetic field in high vacuum. Experimental measurements and finite-element simulations reveal gas collision damping as the dominant loss mechanism at high pressures, while residual eddy damping, which arises from symmetry-breaking factors such as platform tilt or material imperfections, dominates at low pressures. The conclusion is supported by an analytic proof and an analytic example of zero steady current density for a rotating conductor in an axially symmetric magnetic field. This demonstrates a macroscopic levitated rotor with extremely low rotational damping and paves the way to fully suppress rotor damping, enabling ultra-low-loss rotors for gyroscopes, pressure sensing, and fundamental physics tests.
Kim, D., Tian, S., Calderoni, B. et al. A magnetically levitated conducting rotor with ultra-low rotational damping circumventing eddy loss. Commun Phys 8, 381 (2025). doi.org/10.1038/s42005-025-02318-4
