Highly Tunable Photon-Magnon Coupling Governed by Collective-Mode Profiles in Reconfigurable Dielectric-Resonator Arrays

Abstract

The spatial structure of a microwave photon mode provides a degree of freedom for controlling its interaction with a localized magnetic excitation. We demonstrate site-selective magnon-photon coupling in modular arrays of discrete dielectric resonators mounted on a common microstrip line. The resonators can be added, removed, or rearranged on the same completed PCB, enabling post-fabrication geometrical reconfiguration of the collective photon modes and their nodal structure. A YIG sphere is positioned successively above individual resonators, while an in-plane magnetic field tunes its Kittel mode through the collective photon resonances. In a three-resonator array, modes with finite local microwave magnetic fields hybridize with the magnon at every measured site, whereas a mode containing a central field node exhibits no resolvable splitting when the sphere is positioned at that node. Full-wave simulations and a coupled-mode model show that the interaction is governed by the local amplitude of the collective photon mode rather than by spectral resonance alone. Extending this local-node selection rule to a five-resonator array successfully predicts the measured position-dependent coupling patterns. These results establish post-fabrication control of spatial magnon-photon hybridization and provide a route toward reconfigurable magnonic interfaces in future hybrid quantum microwave architectures.