High-efficiency microwave-optical quantum transduction based on a cavity electro-optic superconducting system with long coherence time

TL;DR

This paper presents a high-efficiency microwave-optical quantum transduction system using long-coherence-time superconducting cavities and electro-optic coupling, enabling improved quantum communication, sensing, and entanglement fidelity.

Contribution

It introduces a novel transduction platform with optimized field overlap and long photon lifetimes, achieving up to 50% efficiency in the quantum regime.

Findings

Achieved up to 50% transduction efficiency at milli-Kelvin temperatures.

Enhanced fidelity of heralded entanglement between remote quantum systems.

Enabled high-precision quantum sensing below the standard quantum limit.

Abstract

Frequency conversion between microwave and optical photons is a key enabling technology to create links between superconducting quantum processors and to realize distributed quantum networks. We propose a microwave-optical transduction platform based on long-coherence-time superconducting radio-frequency (SRF) cavities coupled to electro-optic optical cavities to mitigate the loss mechanisms that limit the attainment of high conversion efficiency. In the design, we optimize the microwave-optical field overlap and optical coupling losses, while achieving long microwave and optical photon lifetime at milli-Kelvin temperatures. This represents a significant enhancement of the transduction efficiency up to 50% under pump power of 140$\mu$W, corresponding to few-photon quantum regime. Furthermore, this scheme exhibits high resolution for optically reading out the dispersive shift induced by a superconducting transmon qubit coupled to the SRF cavity. We also show that the fidelity of heralded entanglement generation between two remote quantum systems is enhanced by the low microwave losses. Finally, high-precision in quantum sensing can be reached below the standard quantum limit.