A two-way photonic interface for linking Sr+ transition at 422 nm to the telecommunications C-band

TL;DR

This paper presents a bi-directional photonic interface that efficiently converts photons between Sr+ ion emission at 422 nm and the telecom C-band, enabling long-distance quantum communication with low noise.

Contribution

It introduces a novel single-stage, bi-directional conversion interface with notable efficiency and low noise suitable for quantum networks.

Findings

Achieved 9.4% up-conversion efficiency

Achieved 1.1% down-conversion efficiency

Demonstrated low-noise operation compatible with quantum protocols

Abstract

We report a single-stage bi-directional interface capable of linking Sr+ trapped ion qubits in a long-distance quantum network. Our interface converts photons between the Sr+ emission wavelength at 422 nm and the telecoms C-band to enable low-loss transmission over optical fiber. We have achieved both up- and down-conversion at the single photon level with efficiencies of 9.4% and 1.1% respectively. Furthermore we demonstrate noise levels that are low enough to allow for genuine quantum operation in the future.