On-Chip NbN Superconducting Resonators for Hybrid Magnon-Photon Coupled Systems

Inthe application of quantum information transduction with superconducting (SC) qubits, SC resonators play a phenomenal role in magnon-photon coupled systems. We present NbN (T$_{c}$ = 10.8 K) superconducting microstrip resonators tailored for hybrid magnon-photon coupled systems. Our resonators exhibit remarkable coupling capability, enabling rigorous probing of magnon-photon interactions. With a fundamental frequency of 1.4 GHz and a second harmonic of 2.8 GHz, these resonators offer extensive frequency coverage, facilitating the identification and characterization of a wide spectral range. It exhibits a strong magnon-microwave photon coupling with a sphere of yttrium iron garnet (YIG). The average gyromagnetic ratio ((Formula presented)) and coupling strength ((Formula presented)) achieved are 2.7 MHz/Oe and 11.14 MHz, respectively. The NbN SC resonators developed in this work address challenges associated with probing magnon-photon coupling in strong magnetic fields and are expected to serve as a unique platform for studying magnon-photon coupled hybrid devices.