Deutsche Telekom and Qunnect Sustain High-Fidelity Entanglement Over 30 km Fiber for 17 Days

Deutsche Telekom and Qunnect Sustain High-Fidelity Entanglement Over 30 km Fiber for 17 Days

(IN BRIEF) Researchers at Deutsche Telekom Innovation Laboratories and Qunnect have achieved a major quantum networking milestone by maintaining 99% fidelity in entangled photon transmission over 30 km of commercial fiber for 17 days. A separate test also showed successful routing of entangled photons over 82 km while coexisting with classical data, achieving fidelity above 92%. Conducted at T-Labs’ Quantum Lab in Berlin, these experiments demonstrate the viability of using existing telecom infrastructure for future quantum internet applications. The findings pave the way for ultra-secure communications and next-generation services in fields like IoT, aerospace, and precision timing.

(PRESS RELEASE) BONN, 15-Apr-2025 — /EuropaWire/ — Deutsche Telekom Innovation Laboratories (T-Labs), in collaboration with Qunnect, has achieved a key milestone for the future quantum internet: a 17-day field demonstration of stable, high-fidelity quantum entanglement distribution across 30 kilometers of commercially deployed fiber, with 99% fidelity and just 1% network downtime.

Conducted at T-Labs’ Quantum Lab in Berlin, the test utilized polarization-entangled photons transmitted over Deutsche Telekom’s fiber-optic network. Despite changing environmental conditions, the automated system maintained quantum entanglement quality at 99% for over two weeks, outperforming previous metropolitan-scale quantum experiments.

A second field test demonstrated the successful coexistence of quantum and classical traffic, with polarization-entangled photons dynamically routed across multiple paths up to 82 kilometers long, while operating alongside classical data. The experiment reached fidelity rates above 92% and marks the longest demonstration of O-band entanglement distribution with C-band classical multiplexing on commercial fibers to date.

These breakthroughs are foundational to building the quantum internet, a network where quantum bits (qubits) can be distributed reliably to connect quantum computers, sensors, and communication nodes. Polarization qubits are compatible with many quantum devices but are notoriously difficult to stabilize in fiber-optic systems. The success of this trial shows that existing telecom infrastructure can support such quantum applications.

Beyond quantum key distribution, entanglement technology could transform sectors like aerospace, IoT, and industrial operations through ultra-secure communications, precision time synchronization, and quantum-enhanced sensing. As Claudia Nemat, Deutsche Telekom’s Board Member for Technology and Innovation, stated: “Our fiber optics are ready for the Quantum Internet, even today. This breakthrough highlights how we are turning theoretical physics into practical innovation.”

Noel Goddard, CEO of Qunnect, added: “Demonstrating our quantum networking technology over live commercial infrastructure is an essential step toward proving its real-world viability. We’re grateful for the opportunity to work with T-Labs on this pioneering effort.”

Deutsche Telekom’s Quantum Lab in Berlin, established in 2023, provides a unique platform for real-world testing of quantum technologies across its 2,000-kilometer national fiber-optic network. The lab collaborates with technical universities in Berlin, Dresden, and Munich, as well as Fraunhofer HHI and other industry partners, to advance integration of quantum technologies into telecom systems and ensure long-term cybersecurity.

About T-Labs

T-Labs is Deutsche Telekom’s research and development department dedicated to researching disruptive trends and advancing innovation in new technologies to create valuable business opportunities for Deutsche Telekom and its customers. Co-creation is at the core of their mission: they collaborate with academic institutions in research and conduct incubation programs with start-ups, developers, and strategic partners worldwide. They focus on future network technologies, including quantum networks, network security, digital twins, and ongoing technology exploration.

About Qunnect

Qunnect is developing innovative hardware to transform existing fiber optic infrastructures for telecommunications into quantum networks. Following the launch of the world’s first commercial quantum memory in 2021, the company developed a multi-product drop-in suite to generate, maintain, and validate entanglement distributed across optical fibers. In 2024, the company unveiled the Gotham Rack, a turnkey system that allows users to replicate the protocols demonstrated on GothamQ, a commercial fiber optic network built by Qunnect in New York City. For more information, visit www.qunnect.inc.

Media Contact:

Verena Fulde
Spokesperson and Telekom Blogger
media@telekom.de
+49 228 181 49494

SOURCE: Deutsche Telekom AG