Nanomagnonic cavities for strong spin-magnon coupling

TL;DR

This paper proposes a theoretical method to use magnetic nanoparticles as nanocavities for microwave fields, enabling strong coupling with spin qubits and advancing quantum information transfer and processing.

Contribution

It introduces a novel theoretical framework for nanomagnonic cavities that achieve strong magnon-spin coupling at subwavelength scales, facilitating quantum network development.

Findings

Nanomagnonic cavities can concentrate microwave magnetic fields into extremely small volumes.

Strong coupling between single magnons and spin qubits is theoretically achievable.

Potential for long-range quantum state transfer using these nanocavities.

Abstract

We present a theoretical approach to use ferro- or ferrimagnetic nanoparticles as microwave nanomagnonic cavities to concentrate microwave magnetic fields into deeply subwavelength volumes $\sim 10^{-13}$ mm$^3$. We show that the field in such nanocavities can efficiently couple to isolated spin emitters (spin qubits) positioned close to the nanoparticle surface reaching the single magnon-spin strong-coupling regime and mediate efficient long-range quantum state transfer between isolated spin emitters. Nanomagnonic cavities thus pave the way towards magnon-based quantum networks and magnon-mediated quantum gates.