Travelling photons mediated interactions between a magnon mode and a cavity photon mode

TL;DR

This paper investigates how travelling photons in a waveguide mediate indirect interactions between a magnon mode and a cavity photon mode, providing theoretical analysis and experimental validation of the coupling mechanism.

Contribution

It introduces a theoretical framework for travelling photon mediated coupling and demonstrates experimental verification, clarifying a dissipative interaction mechanism in cavity magnonics.

Findings

Indirect coupling observed via transmission spectra

Theoretical and experimental results show mode hybridization

Travelling photons enable coupling without spatial overlap

Abstract

We systematically study the indirect interaction between a magnon mode and a cavity photon mode mediated by travelling photons of a waveguide. From a general Hamiltonian, we derive the effective coupling strength between two separated modes, and obtain the theoretical expression of system's transmission. Accordingly, we design an experimental set-up consisting of a shield cavity photon mode, microstrip line and a magnon system to test our theoretical predictions. From measured transmission spectra, indirect interaction, as well as mode hybridization, between two modes can be observed. All experimental observations support our theoretical predictions. In this work, we clarify the mechanism of travelling photon mediated interactions between two separate modes. Even without spatial mode overlap, two separated modes can still couple with each other through their correlated dissipations into a mutual travelling photon bus. This conclusion may help us understand the recently discovered dissipative coupling effect in cavity magnonics systems. Additionally, the physics and technique developed in this work may benefit us in designing new hybrid systems based on the waveguide magnonics.