Chip-integrated visible-telecom photon pair sources for quantum communication

TL;DR

This paper presents a novel chip-integrated visible-telecom photon pair source using silicon nitride resonators, enabling efficient quantum communication bridging local quantum systems and fiber networks with high purity and brightness.

Contribution

The authors develop the first integrated visible-telecom photon pair source with high CAR and dispersion engineering for connecting various quantum systems to telecom networks.

Findings

Achieved a photon pair source with CAR up to 3800.

Demonstrated dispersion engineering for connecting different quantum emitters.

Produced bright, narrow-band photon pairs suitable for quantum communication.

Abstract

Photon pair sources are fundamental building blocks for quantum entanglement and quantum communication. Recent studies in silicon photonics have documented promising characteristics for photon pair sources within the telecommunications band, including sub-milliwatt optical pump power, high spectral brightness, and high photon purity. However, most quantum systems suitable for local operations, such as storage and computation, support optical transitions in the visible or short near-infrared bands. In comparison to telecommunications wavelengths, the significantly higher optical attenuation in silica at such wavelengths limits the length scale over which optical-fiber-based quantum communication between such local nodes can take place. One approach to connect such systems over fiber is through a photon pair source that can bridge the visible and telecom bands, but an appropriate source, which should produce narrow-band photon pairs with a high signal-to-noise ratio, has not yet been developed in an integrated platform. Here, we demonstrate a nanophotonic visible-telecom photon pair source for the first time, using high quality factor silicon nitride resonators to generate bright photon pairs with an unprecedented coincidence-to-accidental ratio (CAR) up to (3800 +/- 200). We further demonstrate dispersion engineering of the microresonators to enable the connection of different species of trapped atoms/ions, defect centers, and quantum dots to the telecommunications bands for future quantum communication systems.