Magnon-Enhanced Spin-Based Transduction for Coherent Microwave-to-Optical Conversion

Tharnier Puel De Oliveira, Ph.D.

The lack of a direct interface between microwave-frequency qubits and optical photons remains a critical bottleneck for quantum networks. Efficient, low-noise quantum transduction is essential to bridge superconducting qubits with optical links, yet most existing platforms fail to meet the stringent requirements for fidelity, speed, and integration.

This talk explores a spin-based transduction approach leveraging rare-earth ions in magnetic hosts. Rare-earth ions offer atom-like energy levels via localized 4f electrons, with the ability to realize high-density doping, enabling optical addressability and long coherence times. While commercial rare-earth-doped materials have demonstrated basic quantum functionality, key metrics (such as spin-photon coupling strength) remain insufficient for coherent conversion.

We propose embedding rare-earth ions within ferromagnetic materials to exploit strong spin-magnon coupling. As shown in [arXiv:2411.12870], this hybrid magnonic environment can enhance transduction rates by over two orders of magnitude, enabling faster, more robust conversion with reduced device constraints. This architecture opens new pathways toward scalable, high-bandwidth quantum transducers compatible with microwave qubit platforms. We conclude with implementation strategies for spin-magnon coupling.