Strong spin-magnon coupling in a van der Waals magnet with tunable chiral symmetry

TL;DR

This paper demonstrates strong, tunable spin-magnon coupling in a van der Waals magnet, enabling coherent quantum interfaces and dynamic control of magnon symmetry for scalable chiral quantum optics.

Contribution

It introduces a method to achieve and tune strong spin-magnon coupling in a van der Waals magnet, realizing magnon quantum electrodynamics with dynamic symmetry control.

Findings

Observation of anticrossings and hybridization between spin qubits and magnons.

Dynamic tuning of magnon symmetry from linear to chiral by magnetic field rotation.

Establishment of magnonic cavities as platforms for scalable chiral quantum optics.

Abstract

Quantum technologies require platforms that can coherently interface qubits with bosonic excitations. Photons have traditionally played this role in cavity quantum electrodynamics, but achieving the same goal using solid-state bosons remains challenging. Here we demonstrate strong and tunable spin-magnon coupling between molecular spin qubits and magnons in a van der Waals antiferromagnetic insulator. Using [Gd(W$_5$O$_{18}$)$_{2}$]$^{9-}$ as the spin ensemble and CrSBr as the magnonic resonator, we observe anticrossings and coherent hybridization, realizing magnon quantum electrodynamics for the first time. Crucially, by rotating the magnetic field, we can dynamically change the magnon symmetry from linear to chiral, enabling in-situ tuning of the coupling strength. Our results establish magnonic cavities as a platform for scalable chiral quantum optics with magnetic materials.