Strong magnon–photon coupling with chip-integrated YIG in the zero-temperature limit

The cross-integration of spin-wave and superconducting technologies is a promising method for creating novel hybrid devices future information processing to store, manipulate, or convert data in both classical quantum regimes. Hybrid magnon-polariton systems have been widely studied using bulk Yttrium Iron Garnet (Y$_{3}$Fe$_{5}$O$_{12}$, YIG) three-dimensional microwave photon cavities. However, limitations YIG growth thus far prevented its incorporation into CMOS compatible technology such as high quality factor technology. To overcome this impediment, we used Plasma Focused Ion Beam (PFIB) -- taking advantage precision placement down the micron-scale integrate with devices. Ferromagnetic resonance has measured at millikelvin temperatures on PFIB-processed samples planar circuits. Furthermore, demonstrate strong coupling between resonator ferromagnetic modes by maintaining reasonably low loss while reducing system micron scale. This achievement on-chip crucial step toward fabrication functional that from components.