Dr. Yi. Li, Argonne National Laboratory

Recently, hybrid dynamic systems based on magnetic materials have attracted increasing interests as a new branch in quantum information science. Magnetic excitations, or magnons, are collective excitation of magnetic moments with frequencies in the range of GHz to THz. Due to diverse coupling mechanisms, magnons can be coupled to a wide variety of excitations such as microwave, optic light, phonons and spins. They are promising for coherent information transfer between distinct physical platforms, making them promising for exploring potentials in quantum sensing and quantum transduction.

In this talk, we develop a superconducting circuit platform for implementing on-chip hybrid magnonic system, where the magnon mode is strongly coupled to the photon mode. In the first example, we explore the use of permalloy (Ni₈₀Fe₂₀) thin film devices, where permalloy is a classical metallic ferromagnet with well-known magnetic dynamic properties and is easy to grow and integrate into complex devices [1]. In the second example, we incorporate chip-mounted single-crystal YIG spheres, where YIG exhibit the lowest damping in the known magnetic materials. In particular, we demonstrate microwave-mediated distant magnon-magnon interactions by coupling two remote YIG spheres to a superconducting resonator as a coherent data bus [2]. In addition, we demonstrate time-domain magnon interference between the two remotely coupled YIG spheres [3]. Our results provide a realistic platform for constructing hybrid magnonic quantum networks at cryogenic temperatures and that can be scaled up and incorporated into integrated circuits.

[1] Y. Li et al., Strong coupling between magnons and microwave photons in on-chip ferromagnet-superconductor thin-film devices, Phys. Rev. Lett. 123, 107701 (2019)

[2] Y. Li et al., Coherent coupling of two remote magnonic resonators mediated by superconducting circuits, Phys. Rev. Lett. 128, 047701 (2022)

[3] M. Song et al., Programmable Real-Time Magnon Interference in Two Remotely Coupled Magnonic Resonators, arXiv:2309.04289