Design of a system for controlling a levitating sphere in superfluid $^3$He at extremely low temperatures

TL;DR

This paper introduces a novel mechanical system for levitating and controlling a sphere in superfluid helium-3 at microkelvin temperatures, enabling advanced studies of topological superfluid properties.

Contribution

It presents a new experimental setup with control and stability analysis for levitating a superconducting sphere in superfluid helium-3 at ultra-low temperatures.

Findings

Successful design of a levitation control system

Simulation results demonstrating device stability

Potential to explore edge states in topological superfluid $^3$He-B

Abstract

We present a new mechanical probe to study the properties of superfluid $^3$He at microkelvin temperatures down to 100$\mu$K. The setup consists of a set of coils for levitating a superconducting sphere and controlling its motion in a wide variety of regimes. In particular, the realisation of motion of a levitating body at a uniform velocity presents both an experimental challenge and a promising direction into the study of the edge states in topological superfluid $^3$He-B. We include the theoretical study of the device stability and simulations to illustrate the capabilities of the control system.