Microwave-to-optical quantum transducers

An apparatus, comprising:

• a dielectric substrate;
• a microwave resonator on the dielectric substrate, the microwave resonator including a superconducting waveguide;
• an optical resonator in the dielectric substrate;
• and
• a photon barrier structure at least partially surrounding the optical resonator.

A method, comprising:

• forming an optical resonator in a dielectric substrate;
• forming a photon barrier structure in the dielectric substrate, wherein the photon barrier structure at least partially surrounds the optical resonator;
• and
• forming a superconducting microwave resonator on the dielectric substrate.