Bidirectional interconversion of microwave and light with thin-film lithium niobate

Abstract Superconducting cavity electro-optics presents a promising route to coherently convert microwave and optical photons distribute quantum entanglement between superconducting circuits over long-distance. Strong Pockels nonlinearity high-performance are the prerequisites for high conversion efficiency. Thin-film lithium niobate (TFLN) offers these desired characteristics. Despite significant recent progresses, only unidirectional with efficiencies on order of 10 −5 has been realized. In this article, we demonstrate bidirectional electro-optic in TFLN-superconductor hybrid system, efficiency improved by more than three orders magnitude. Our air-clad device architecture boosts sustainable intracavity pump power at cryogenic temperatures suppressing prominent photorefractive effect that limits performance TFLN, reaches an 1.02% (internal 15.2%). This work firmly establishes EO system as highly competitive transduction platform future network applications.