Long-distance strong coupling of magnon and photon: Effect of multi-mode waveguide

TL;DR

This paper investigates how multi-mode waveguides enable strong long-distance coupling between magnons and photons, surpassing traditional weak coupling predictions, with implications for quantum network design.

Contribution

It demonstrates that strong magnon-photon coupling over long distances requires both critical coupling and multi-mode waveguides, providing a new understanding of long-distance quantum interactions.

Findings

Strong coupling achieved with multi-mode waveguides and critical coupling.

Multi-mode waveguides increase coupling pathways, reducing damping effects.

Results support development of magnon-based distributed quantum networks.

Abstract

Coupled mode theory predicts that the long-distance coupling between two distant harmonic oscillators is in the weak coupling regime. However, a recent experimental measurement observed strong coupling of magnon and critically-driven photon with a distance of over two meters. To explain the discrepancy between theory and experiment, we study long-distance coupling of magnon and photon mediated by a multi-mode waveguide. Our results show that strong coupling is achieved only when both critical coupling and multi-mode waveguide are involved. The former reduces the damping while the latter enhances the coupling strength by increasing the pathways of coupling magnon and photon. Our theory and results pave the way for understanding the long-distance coherence and designing the magnon-based distributed quantum networks.