Kinetic Inductive Electromechanical Transduction for Nanoscale Force Sensing

TL;DR

This paper introduces a novel nanoscale force sensor based on kinetic inductive electromechanical transduction, utilizing cavity optomechanics principles to detect cantilever motion with high sensitivity.

Contribution

It presents a new force sensing mechanism using kinetic inductance changes in superconducting nanowires, expanding the toolkit for atomic force microscopy.

Findings

Kinetic inductive mechano-electric coupling rate estimated at 3-10 Hz.

Demonstrated phase-sensitive detection of cantilever motion.

Designed a fully coplanar resonant mechanical force sensor.

Abstract

We use the principles of cavity optomechanics to design a resonant mechanical force sensor for atomic force microscopy. The sensor is based on a type of electromechanical coupling, dual to traditional capacitive coupling, whereby the motion of a cantilever induces surface strain that causes a change in the kinetic inductance of a superconducting nanowire. The cavity is realized by a compact microwave-plasma mode with an equivalent $LC$ circuit involving the kinetic inductance of the nanowire. The device is fully coplanar and we show how to transform the cavity impedance for optimal coupling to the transmission line and the following amplifier. For the device presented here, we estimate the bare kinetic inductive mechano-electric coupling (KIMEC) rate $g_0 / 2 \pi$ in the range 3-10 Hz. We demonstrate phase-sensitive detection of cantilever motion using a multifrequency pumping and measurement scheme.