Quantum magnonics: magnon meets superconducting qubit

TL;DR

This paper demonstrates strong coupling between magnons, microwave cavity modes, and superconducting qubits, enabling the creation and analysis of non-classical magnonic quantum states in a hybrid system.

Contribution

It introduces a novel hybrid quantum system combining magnons, microwave cavities, and superconducting qubits, with experimental evidence of magnon-qubit interactions.

Findings

Strong coupling between magnon and cavity modes in the single-magnon limit

Observation of magnon-vacuum-induced Rabi splitting

Generation of non-classical quantum states of magnons

Abstract

The techniques of microwave quantum optics are applied 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. The hybrid quantum system enables generation and characterization of non-classical quantum states of magnons.