Dissipation-based Quantum Sensing of Magnons with a Superconducting Qubit

TL;DR

This paper demonstrates a novel quantum sensing method for magnons using a superconducting qubit, leveraging dissipation and Ramsey interferometry to detect magnon populations with high sensitivity.

Contribution

It introduces a dissipation-based quantum sensing protocol for magnons via a superconducting qubit, enabling sensitive detection of magnon populations.

Findings

Achieved magnon detection sensitivity of 10^{-3} magnons/√Hz.

Demonstrated dispersive coupling for quantum sensing of magnetostatic modes.

Validated dissipation as a resource for quantum sensing in hybrid devices.

Abstract

Hybrid quantum devices expand the tools and techniques available for quantum sensing in various fields. Here, we experimentally demonstrate quantum sensing of the steady-state magnon population in a magnetostatic mode of a ferrimagnetic crystal. Dispersively coupling the magnetostatic mode to a superconducting qubit allows the detection of magnons using Ramsey interferometry with a sensitivity on the order of $10^{-3}$ $\text{magnons}/\sqrt{\text{Hz}}$. The protocol is based on dissipation as dephasing via fluctuations in the magnetostatic mode reduces the qubit coherence proportionally to the number of magnons.