Indirect coupling of magnons by cavity photons

TL;DR

This paper demonstrates long-distance strong coupling between two magnetic spheres mediated by cavity photons, revealing mode splitting and symmetry-breaking effects that enable controlled magnonic interactions in microwave cavities.

Contribution

It introduces a theoretical framework for coupling magnetic spheres via cavity photons beyond standard approximations, highlighting mode splitting and symmetry effects.

Findings

Strong long-distance coupling via cavity modes

Mode splitting into acoustical and optical modes

Symmetry breaking introduces ionic character

Abstract

The interaction between two magnetic spheres in microwave cavities is studied by Mie scattering theory beyond the magnetostatic and rotating wave approximations. We demonstrate that two spatially separated dielectric and magnetic spheres can be strongly coupled over a long distance by standing cavity modes. The interactions splits acoustical (dark) and optical (bright) modes in a way that can be mapped on a molecular orbital theory of the hydrogen molecule. Breaking the symmetry by assigning different radii to the two spheres introduces "ionic" character to the magnonic bonds. These results illustrate the coherent and controlled energy exchange between objects in microwave cavities.