Two-photon interference between disparate sources for quantum networking

TL;DR

This paper demonstrates high-visibility two-photon interference between different types of photon sources at telecom wavelengths, advancing the development of hybrid quantum networks for long-distance communication.

Contribution

It reports the first successful two-photon interference between disparate heralded single photon sources in the telecom range, overcoming previous wavelength and visibility limitations.

Findings

Achieved 80+/-4% interference visibility.

Used different nonlinear effects for photon generation.

Operated in the telecom wavelength range for long-distance suitability.

Abstract

Quantum networks involve entanglement sharing between multiple users. Ideally, any two users would be able to connect regardless of the type of photon source they employ, provided they fulfill the requirements for two-photon interference. From a theoretical perspective, photons coming from different origins can interfere with a perfect visibility, provided they are made indistinguishable in all degrees of freedom. Previous experimental demonstrations of such a scenario have been limited to photon wavelengths below 900 nm, unsuitable for long distance communication, and suffered from low interference visibility. We report two-photon interference using two disparate heralded single photon sources, which involve different nonlinear effects, operating in the telecom wavelength range. The measured visibility of the two-photon interference is 80+/-4%, which paves the way to hybrid universal quantum networks.