Giant spin ensembles in waveguide magnonics.

Area of Science:

• Quantum Optics and Photonics
• Condensed Matter Physics
• Artificial Atom Systems

Background:

• The dipole approximation is standard for light-matter interactions but fails for systems comparable to light wavelengths.
• Artificial 'giant atom' systems, where atom size approaches light wavelength, exhibit unique physics beyond the dipole approximation.
• These systems offer potential for novel applications due to their distinct quantum behaviors.

Purpose of the Study:

• To experimentally realize and investigate a 'giant atom' system using a ferromagnetic spin ensemble.
• To explore the tunable coupling dynamics between the giant spin ensemble and a waveguide.
• To study the collective behaviors of nested giant spin ensembles.

Main Methods:

• Fabrication of a giant spin ensemble (GSE) from a ferromagnetic material.
• Interaction of the GSE with a meandering waveguide, allowing for multiple light-matter interactions.
• Continuous tuning of the coupling strength between the GSE and waveguide by frequency variation.

Main Results:

• Demonstration of a tunable coupling strength between the GSE and waveguide, ranging from coupled to decoupled states.
• Observation of unique collective phenomena in a nested configuration of two GSEs.
• Validation of the 'giant atom' physics regime in a macroscopic spin system.

Conclusions:

• The developed giant spin ensemble provides a novel experimental platform for exploring 'giant atom' physics.
• Tunable coupling and collective behaviors in GSEs open avenues for new quantum phenomena and applications.
• This work extends 'giant atom' physics beyond conventional atomic systems.