MW-Magnon Systems for Quantum Transduction Applications

Hybrid Quantum Systems (HQS), consisting of microwave (MW) and optic subsystems interacting through a magnon interface, have attracted the remarkable attention of researchers because of the very intriguing basic physics involved and many potential applications in various fields of quantum technology (e.g., quantum transduction and communication). It has been already shown that a strong coupling between the Yttrium Iron Garnet (YIG) sphere and the 3D microwave resonator with a formation of the Cavity-Magnon-Polariton (CMP) is achievable. Recently, the systems based on the use of planar (2D) MW resonators and YIG crystals or films have attracted research attention because they are very interesting from the point of view of their integration with the quantum circuits based on planar superconducting elements. It has been already shown that a strong coupling regime in 2D systems can be also obtained. Furthermore, the novel physics observed in the planar geometries is believed to provide a platform for the realization of many other applications, for instance, in highly sensitive RF/MW sensors. In this work, the state of the art of HQSs based on magnon materials is briefly reviewed. Approaches for analyzing and modeling these systems and their applicability for the various configurations are discussed. Finite Element Method (FEM) simulations of the hybrid magnon systems, consisting of MW resonators and YIG crystals (for scales larger than the exchange length) are demonstrated to provide a powerful tool for the analysis of these systems. An example of the experimental realization of HQSs based on the planar MW resonator coupled to the magnetic resonance mode of the YIG thin film is given. A good agreement between the experimental and modeling results reveals that FEM simulations are a powerful tool for the analysis of these systems in the case of the HQS scale larger than the magnon-material exchange length.