High sensitivity cantilevers for measuring persistent currents in normal metal rings

TL;DR

This paper introduces a novel cantilever-based method for measuring persistent currents in normal metal rings, offering potentially higher sensitivity and cleaner electromagnetic environments compared to traditional techniques.

Contribution

The paper presents the design, fabrication, and analysis of ultra-sensitive cantilevers integrated with metal rings for improved persistent current detection.

Findings

Measured mechanical properties of fabricated cantilevers

Estimated persistent current sensitivity limited by Brownian motion and shot noise

Proposed method could surpass existing SQUID and microwave resonator detectors

Abstract

We propose a new approach to measuring persistent currents in normal metal rings. By integrating micron-scale metal rings into sensitive micromechanical cantilevers and using the cantilevers as torque magnetometers, it should be possible to measure the rings' persistent currents with greater sensitivity than the SQUID-based and microwave resonator-based detectors used in the past. In addition, cantilever-based detectors may allow for measurements in a cleaner electromagnetic environment. We have fabricated ultra sensitive cantilevers with integrated rings and measured their mechanical properties. We present an estimate of the persistent current sensitivity of these cantilever-based detectors, focusing on the limits set by the cantilever's Brownian motion and the shot noise in the laser interferometer that monitors the cantilever.