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

TL;DR

This paper demonstrates strong magnon-photon coupling on-chip by integrating YIG with superconducting circuits using plasma focused ion beam technology at millikelvin temperatures, advancing hybrid quantum device fabrication.

Contribution

It introduces a novel method to integrate YIG with superconducting devices at micron scale using PFIB, enabling strong coupling in a chip-compatible manner.

Findings

Strong coupling achieved between superconducting resonator and YIG ferromagnetic resonance.

YIG integrated with superconducting circuits maintains low loss at millikelvin temperatures.

On-chip strong magnon-photon coupling demonstrated at micron scale.

Abstract

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