The Saturable Electronic Reluctance Switch: Switchable low-power and low-noise generation of magnetic fields using permanent magnets

TL;DR

The paper introduces the Saturable Electronic Reluctance Switch (SERS), a hybrid magnetic switch that provides ultra-stable, low-noise, and low-power magnetic field control suitable for quantum computing and other applications.

Contribution

A novel bi-stable magnetic switching technique using a non-linear ferromagnetic circuit that reduces power dissipation and noise compared to existing methods.

Findings

SERS achieves bi-stable switching with minimal influence on magnetic field output.

The device reduces power dissipation by an order of magnitude compared to traditional wires.

Magnetic field noise from current fluctuations is suppressed by up to five orders of magnitude.

Abstract

Across many areas of science, there is a need to generate magnetic fields that are both ultra-stable and switchable on and off. While permanent and superconducting magnets offer exceptionally low-noise fields, they are not readily switchable. Conversely, electromagnets are switchable but are susceptible to current noise. We present a hybrid technique to switch the field of any arbitrary magnet through use of a non-linear ferromagnetic circuit, named the Saturable Electronic Reluctance Switch (SERS). The circuit achieves bi-stable switching of the field by applying a current above a given threshold, akin to a transistor for magnetic fields. Crucially, the applied current has minimal influence on the magnetic field output and demagnetisation of the magnet is avoided, drastically reducing power dissipation. SERS is also robust to fabrication errors, suppressing noise in the control current by several orders of magnitude in a non-ideal device. To illustrate its application, a SERS-driven device is proposed for generating ultra-stable magnetic field gradients in a scalable trapped-ion quantum computer. We find this device offers an order of magnitude reduction in power dissipation compared to state-of-the-art current carrying wires, while reducing magnetic field noise originating from current fluctuations by up to five orders of magnitude.