Applications and Significance of Magneto-Optical Garnets in Quantum Computing and the Quantum Internet

Applications and Significance of Magneto-Optical Garnets in Quantum Computing and the Quantum Internet Mehmet Keçeci Orcid: https://orcid.org/0000-0001-9937-9839 Abstract: Magneto-optical garnets, and in particular yttrium iron garnet (YIG, Y₃Fe₅O₁₂), have emerged as a critical interface material in quantum information processing technologies. Superconducting qubits typically operate with microwave photons in the gigahertz regime, whereas long-distance quantum communication relies on visible or near-infrared photons propagating through optical fibres. The ability to coherently link these two fundamentally different physical platforms constitutes a prerequisite for scalable quantum computing architectures and a global quantum internet. Owing to their exceptionally low magnetic damping, high spin density, optical transparency in the near-infrared window, and pronounced Faraday effect, YIG and related garnet compounds provide a versatile hybrid platform that supports coherent quantum state transfer among microwave photons, optical photons, phonons, and superconducting qubits. In this work we review the fundamental physical properties of magneto-optical garnets, their roles in quantum magnonics and optomagnonics, their potential for microwave-to-optical quantum transduction, their functionality in optical isolation and nonreciprocal photonic devices, and the principal technological limitations that currently constrain their performance. We further assess the strategic significance of these materials for distributed quantum computing and quantum internet architectures. Keywords: magneto-optical, garnet, YIG, quantum magnonics, quantum transduction, quantum internet, superconductingqubit, optical isolator, nanostructures, yttrium.