Optomagnonics in Magnetic Solids

TL;DR

This paper explores optomagnonics in magnetic solids, demonstrating how photon-magnon interactions can be coherently controlled in optical cavities, potentially enabling advanced quantum information processing and communication technologies.

Contribution

It introduces a theoretical framework for strong photon-magnon coupling in magnetic insulators, surpassing previous optomechanical coupling strengths, and predicts observable quantum effects.

Findings

Calculated intrinsic photon-magnon coupling exceeds optomechanical couplings.

Predicted conditions for electromagnetically induced transparency and Purcell effect.

Potential to reach ultra-strong coupling regime in magnetic solid systems.

Abstract

Coherent conversion of photons to magnons, and back, provides a natural mechanism for rapid control of interactions between stationary spins with long coherence times and high-speed photons. Despite the large frequency difference between optical photons and magnons, coherent conversion can be achieved through a three-particle interaction between one magnon and two photons whose frequency difference is resonant with the magnon frequency, as in optomechanics with two photons and a phonon. The large spin density of a transparent ferromagnetic insulator (such as the ferrite yttrium iron garnet) in an optical cavity provides an intrinsic photon-magnon coupling strength that we calculate to exceed reported optomechanical couplings. A large cavity photon number and properly selected cavity detuning produce a predicted effective coupling strength sufficient for observing electromagnetically induced transparency and the Purcell effect, and even to reach the ultra-strong coupling regime.