Terahertz-mediated microwave-to-optical transduction

Transduction of quantum signals between the microwave and the optical ranges will unlock powerful hybrid quantum systems enabling information processing with superconducting qubits and low-noise quantum networking through optical photons. Most microwave-to-optical quantum transducers suffer from thermal noise due to pump absorption. We analyze the coupled thermal and wave dynamics in electro-optic transducers that use a two-step scheme based on an intermediate frequency state in the THz range. Our analysis, supported by numerical simulations, shows that the two-step scheme operating with a continuous pump offers near-unity external efficiency with a multiorder noise suppression compared to single-step transduction. As a result, two-step electro-optic transducers may enable quantum-noise-limited interfacing of superconducting quantum processors with optical channels at MHz-scale bit rates.