Yasunobu Nakamura

Quantum magnonics   

The University of Tokyo / RIKEN   

The circuit quantum electrodynamics architecture using microwave resonators and superconducting qubits allows flexible designs and realizations of hybrid quantum systems. We apply it to collective spin excitations in a macroscopic sphere of ferromagnetic insulator. We demonstrate, in the single-magnon limit, strong coupling between a magnetostatic mode in the sphere and a microwave cavity mode. Moreover, we introduce a superconducting qubit in the cavity and couple the qubit with the magnon excitation via the virtual photon excitation. We observe the magnon-vacuum-induced Rabi splitting and oscillations. The hybrid quantum system enables generation and characterization of non-classical quantum states of magnons.