Ultra-low damping of the translational motion of a composite graphite rod in a magneto-gravitational trap

TL;DR

This paper reports the creation of a highly isolated, low-damping mechanical oscillator using a levitated composite graphite rod in a magneto-gravitational trap, with potential applications in sensing.

Contribution

It introduces a novel magneto-gravitational trapping method that achieves ultra-low damping of a levitated graphite rod at room temperature, surpassing previous damping levels.

Findings

Vertical motion damps in seconds

Axial motion damps over 5 days

Magnetic field symmetry reduces damping

Abstract

We demonstrate an ultra-low dissipation, one-dimensional mechanical oscillator formed by levitating a millimeter-scale composite graphite rod in a room-temperature magneto-gravitational trap. The trap's magnetic field geometry, based on a linear quadrupole, eliminates first-order field gradients in the axial direction, yielding a low oscillation frequency with ultra-low eddy-current losses. Direct ring-down measurements under vacuum compare the damping of the vertical and axial motion; while the vertical motion damps in seconds, the axial motion damps with a time constant of over 5 days. Analysis reveals that this dramatic difference in damping is a result of the symmetry of the magnetic field and the anisotropy of the trap strength. The results are remarkably robust, demonstrating a potential platform for inertial and gravitational sensing.