Fraunhofer HHI joins Q.Link.X quantum network consortium, sponsored by German Ministry of Education

Created October 19, 2018
The Fraunhofer Heinrich Hertz Institute HHI is one of 24 partners who have joined forces to research the key technologies involved in quantum repeatersApplications and Research

The German Federal Ministry of Education and Research (BMBF) is supporting the country’s quantum R&D revolution by investing €14.8 million in a new collaborative project called Quanten-Link-Erweiterung (“Q.Link.X”) set to run over the next three years.

“The objectives are optical cable networks that are physically tap-proof,” says Q.Link.X project consortium representative Prof. Dr. Dieter Meschede of the Institute of Applied Physics at the University of Bonn.

As digitalisation is penetrating every aspect of our society – from the Industrial Internet through to healthcare applications – data safety and secure communications are becoming more and more important, states last consortium member Fraunhofer HHI.

“Quantum communication is a very promising approach in this context: Its information medium is based on quantum states, which, because of fundamental physical laws, can neither be copied nor intercepted without being detected.”


However, this paradigm shift in information encryption, away from conventional methods and towards quantum technologies, faces a technological challenge: transmitting quantum information using photons entails unavoidable transmission line losses that up to now have limited the viable transmission distance to less than around 100 km.

But now this limitation is set to be overcome without compromising security using an innovation known as quantum repeaters (QR). In classic communications technologies, repeaters prepare and amplify signals. In contrast, quantum repeaters link signals of various sub-segments using quantum processes in order to successfully transmit across greater distances.

The Fraunhofer Heinrich Hertz Institute HHI is one of 24 partners who have joined forces to research the key technologies involved in quantum repeaters. The goal of the Fraunhofer HHI is the provision of an application-oriented test environment consisting of installed optical cables for testing QR components, QR cells and QR segments developed in the consortium.


The laboratories of the Fraunhofer HHI will be connected to previously installed optical cables for this purpose. The project will also investigate enhanced protocols in terms of wavelength multiplexing with additional quantum communications and classical transmission channels for existing optical cable communications networks.

Transmission segments of between ten and one hundred kilometres in length are to be realised using three different technical platforms: quantum dots, diamond colour centres and a combination of atomic and ionic systems. The benefits of the respective systems are to be compared with one another.

“Q.Link.X will develop for the first time a quantum repeater that will be tested on installed optical cables. This is an important step towards bringing this technology into the application phase,” commented Prof. Dr. Ronald Freund, head of the Photonic Networks and Systems department at Fraunhofer HHI.

The Q.Link.X consortium unites a variety of partners ranging from research facilities and universities to industrial laboratories. The close integration of industrial partners and consultants is intended to facilitate from the very beginning the feasibility from an industrial and technical point of view. The exploitation of the results in Germany is to be protected by patents and ensured through spin-off companies originating from the consortium.

The news comes on the heels of the announcement that Spanish researchers have developed a quantum cryptography network integrated into a commercial optical network using technologies based on software defined networking (SDN). The design allows for the implementation of quantum and classical network services in what the developers call “a flexible, dynamic and scalable manner”.

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This article was written
by Matthew Peach

Matthew Peach is a freelance technology journalist specialising in photonics and communications. He has previously worked for several business-to-business publishers, editing a range of high-tech magazines and websites.