Giant spin ensembles in waveguide magnonics

TL;DR

This paper demonstrates a giant spin ensemble interacting with a waveguide, revealing tunable coupling and collective phenomena that extend the physics of small atoms to larger, more complex systems.

Contribution

It introduces the experimental realization of a giant spin ensemble in waveguide magnonics, enabling tunable coupling and exploration of collective behaviors beyond traditional atomic systems.

Findings

Tunable coupling strength from finite to zero by frequency variation.

Observation of collective phenomena in nested GSE configurations.

Experimental platform for giant atom physics in magnonic systems.

Abstract

The dipole approximation is usually employed to describe light-matter interactions under ordinary conditions. With the development of artificial atomic systems, `giant atom' physics is possible, where the scale of atoms is comparable to or even greater than the wavelength of the light they interact with, and the dipole approximation is no longer valid. It reveals interesting physics impossible in small atoms and may offer useful applications. Here, we experimentally demonstrate the giant spin ensemble (GSE), where a ferromagnetic spin ensemble interacts twice with the meandering waveguide, and the coupling strength between them can be continuously tuned from finite (coupled) to zero (decoupled) by varying the frequency. In the nested configuration, we investigate the collective behavior of two GSEs and find extraordinary phenomena that cannot be observed in conventional systems. Our experiment offers a new platform for `giant atom' physics.