Coherent coupling between a ferromagnetic magnon and a superconducting qubit

Rigidity of an ordered phase in condensed matter results in collective excitation modes spatially extending to macroscopic dimensions. A magnon is a quantum of such collective excitation modes in ordered spin systems. Here, we demonstrate the coherent coupling between a single-magnon excitation in a millimeter-sized ferromagnetic sphere and a superconducting qubit, with the interaction mediated by the virtual photon excitation in a microwave cavity. We obtain the coupling strength far exceeding the damping rates, thus bringing the hybrid system into the strong coupling regime. Furthermore, we use a parametric drive to realize a tunable magnon-qubit coupling scheme. Our approach provides a versatile tool for…

• MO
  Ministry of Education, Culture, Sports, Science and Technology
• MS
  Murata Science Foundation
• RF
  Research Foundation for Opto-Science and Technology
• JS
  Japan Society for the Promotion of Science

  Awards: 26220601, 26600071
• NI
  National Institute of Information and Communications Technology