Methods for microwave characterization of electro-optic crystals for quantum transduction

Abstract

Microwave-optic quantum transducers are essential to develop distributed quantum networks and implement related quantum communication protocols. Three dimensional high-coherence microwave cavities embedded with electro-optic nonlinear materials provide promising platforms for microwaveoptic frequency conversion. However, so far, the properties for such dielectric crystals operating at milli-Kelvin cryogenic temperatures have not been well understood. Here, we propose a scheme to precisely measure the dielectric constant and dissipation mechanisms of electro-optic materials, such as Lithium Niobate, at the quantum threshold. We will use Fermilab's three dimensional superconducting cavities with long coherence time. The proposed method of characterization lays the foundation for engineering quantum transduction devices with high conversion efficiency and high-fidelity.