Dispersive read-out of ferromagnetic resonance for strongly coupled magnons and microwave photons

TL;DR

This paper demonstrates a dispersive measurement technique for ferromagnetic resonance in a yttrium iron garnet sphere coupled with a microwave cavity, highlighting potential for quantum magnonic experiments.

Contribution

It introduces a dispersive read-out method for ferromagnetic resonance, leveraging intrinsic non-linearity in magnetization dynamics for quantum applications.

Findings

Measured frequency shifts corresponding to magnetization changes

Confirmed strong coupling between magnons and microwave photons

Showed potential for quantum magnonic experiments

Abstract

We demonstrate the dispersive measurement of ferromagnetic resonance in a yttrium iron garnet sphere embedded within a microwave cavity. The reduction in the longitudinal magnetization at resonance is measured as a frequency shift in the cavity mode coupled to the sphere. This measurement is a result of the intrinsic non-linearity in magnetization dynamics, indicating a promising route towards experiments in magnon cavity quantum electro-dynamics.