On-chip microwave-to-optical quantum coherent converter based on a superconducting resonator coupled to an electro-optic microresonator

TL;DR

This paper proposes a superconducting-resonator-based device for efficient microwave-to-optical quantum conversion, leveraging electro-optical coupling in a hybrid system suitable for quantum communication.

Contribution

It introduces a novel on-chip architecture combining superconducting circuits with electro-optical microresonators for quantum photon conversion.

Findings

Electro-optical coupling rates of 10-100 kHz are achievable with current technology.

Maximum conversion efficiency occurs at a multi-photon cooperativity of unity.

Conversion can be achieved with low optical power (~1 mW) at millikelvin temperatures.

Abstract

We propose a device architecture capable of direct quantum electro-optical conversion of microwave to optical photons. The hybrid system consists of a planar superconducting microwave circuit coupled to an integrated whispering-gallery-mode microresonator made from an electro-optical material. We show that electro-optical (vacuum) coupling rates $g_0$ as large as$\sim 2\pi \, \mathcal{O}(10-100)$ kHz are achievable with currently available technology, due to the small mode volume of the planar microwave resonator. Operating at millikelvin temperatures, such a converter would enable high-efficiency conversion of microwave to optical photons. We analyze the added noise, and show that maximum conversion efficiency is achieved for a multi-photon cooperativity of unity which can be reached with optical power as low as $ \mathcal{O}(1)\,\mathrm{mW} $.