Long-term transmission of entangled photons from single quantum dot over deployed fiber

TL;DR

This paper demonstrates the week-long stable transmission of polarization-entangled photons from a quantum dot over 18 km of deployed fiber, showing potential for quantum communication in existing networks.

Contribution

It reports the first long-term stable transmission of entangled photons from a quantum dot over real-world fiber infrastructure.

Findings

Achieved 91% fidelity in entanglement transmission.

Maintained stable polarization over 18 km of deployed fiber.

Enabled quantum light sources to operate over existing fiber networks.

Abstract

Non-classical light sources based on a single quantum emitter are considered as core technology for multiple quantum network architectures. A large variety of sources has been developed, but the generated photons remained far from being utilized in established standard fiber networks. Here, we report a week-long transmission of polarization-entangled photons from a single InAs/GaAs quantum dot over a metropolitan network fiber. The emitted photons are in the telecommunication O-band, favored for fiber optical communication. We employ a polarization stabilization system overcoming changes of birefringence introduced by 18.23km of installed fiber. Stable transmission of polarization-encoded entanglement with a high fidelity of 91% is achieved, facilitating the operation of sub-Poissonian quantum light sources over existing fiber networks.