Damping and non-linearity of a levitating magnet in rotation above a superconductor

J Druge,M-A Méasson,I Favero,O Laurent,C Jean

doi:10.1088/1367-2630/16/7/075011

Abstract

We study the dissipation of moving magnets in levitation above a superconductor. The rotation motion is analyzed using optical tracking techniques. It displays a remarkable regularity together with long damping time up to several hours. The magnetic contribution to the damping is investigated in detail by comparing 14 distinct magnetic configurations and points towards amplitude-dependent dissipation mechanisms. The non-linear dynamics of the mechanical rotation motion is also revealed and described with an effective Duffing model. The magnetic mechanical damping is consistent with measured hysteretic cycles M(H) that are discussed within a modified critical state model. The obtained picture of the coupling of levitating magnets to their environment sheds light on their potential as ultra-low dissipation mechanical oscillators for high precision physics.

Highlights

Mechanical oscillators with ultra-low dissipation find applications as frequency standards, probes of minute forces like in Atomic Force Microscopy, or signal processing where they can serve as fine radio-frequency filters
At a basic science level, they received attention in the past for their impact in high precision physics and metrology [1, 2]. They have become a central subject for a whole community of physicists aiming at observing the quantum behavior of mesoscopic mechanical systems [3, 4]
This quest has seen impressive advances notably thanks to optomechanical systems [5, 6, 7, 8] that use the concepts of coupling light and mechanical motion, notably in the regime where the quantumness of the mechanics starts being tangible [9, 10]

Summary

Introduction

Mechanical oscillators with ultra-low dissipation find applications as frequency standards, probes of minute forces like in Atomic Force Microscopy, or signal processing where they can serve as fine radio-frequency filters. Strictly no magnetic damping of the sphere rotation motion should occur. In a rotation around M the amplitude remains constant and the motion is analyzed by registering the phase evolution upon time.

Results

Conclusion