Reconfigurable control of coherence, dissipation, and nonreciprocity in cavity magnonics

Abstract

Abstract Precise control of coupling strength, damping rate and nonreciprocity in photon–magnon systems is essential for advancing hybrid quantum technologies, including reconfigurable microwave components and quantum transducers. Here, we demonstrate magnetic field angle-dependent control of photon–magnon coupling and magnon dissipation in a cross-shaped microwave cavity supporting a spatially nonuniform radio-frequency (rf) magnetic field. By rotating the external magnetic field angle $$\theta$$ relative to the normal of the transmission line within the cavity plane, we simultaneously control the coherent coupling strength $${g}_{0}$$ , the ferromagnetic resonance (FMR) damping rate, and the system’s nonreciprocal response. The nonuniform rf field selectively excites both the uniform FMR mode and finite-wavevector spin waves in an Yttrium Iron Garnet (YIG) film, enabling angle-dependent two-magnon scattering. While typically regarded as a passive loss mechanism, we show that two-magnon scattering can serve as a dynamic and reversible knob to control magnon damping. Moreover, we realise nonreciprocity originating from the spatial asymmetry of the rf field, in addition to conventional phase-based schemes. These findings introduce new opportunities for in situ control of coherence, dissipation, and nonreciprocity in cavity magnonics, with broad implications for reconfigurable quantum and spintronic systems.