Bichromatic Quantum Teleportation of Weak Coherent Polarization States on a Metropolitan Fiber

TL;DR

This paper demonstrates quantum teleportation of weak coherent polarization states over a 30-km metropolitan fiber network using commercial telecom components, achieving high fidelity and compatibility with existing data traffic.

Contribution

First implementation of quantum teleportation on a real telecom fiber network using commercial components and coexistence with classical data channels.

Findings

Achieved 90% teleportation fidelity over 30 km fiber

Demonstrated compatibility with classical data traffic

Validated quantum teleportation under real-world environmental conditions

Abstract

As quantum technologies mature, telecommunication operators have a clear opportunity to unlock and scale new services by providing the connectivity layer that links quantum computers, sensors, clocks, and other quantum devices. Realizing this opportunity requires demonstrating quantum networking protocols, including quantum teleportation, under real-world conditions on existing telecom infrastructure. In this work, we demonstrate quantum teleportation over Deutsche Telekom's metropolitan fiber testbed in Berlin using commercial components deployed at the telecom datacenter. A local Bell-state measurement between 795 nm photons from a weak coherent source and from a bichromatic warm-atom entangled photon source enables conditional state transfer onto an O-band photon, which is transmitted through a 30-km field-deployed fiber loop under real-world environmental conditions. The teleported state is reconstructed after propagation via state tomography, achieving an average teleportation fidelity of 90\% on the deployed link. System performance is evaluated in both the absence and the presence of co-propagating C-band classical traffic within the same fiber, demonstrating compatibility with wavelength-division multiplexed telecom infrastructure carrying live data channels.