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01/09/2025 | Pressemitteilung

Joint project researches quantum repeaters for secure quantum networks of the future

We receive reports of IT sabotage, espionage and "hybrid warfare" on an almost daily basis. Networks based on quantum physics could provide a great deal of security here. The basis for such networks are so-called quantum repeaters, which scientists from all over Germany have been researching for years. The Federal Ministry of Education and Research is now funding a new research project in which quantum repeater concepts are to be demonstrated on test tracks outside of laboratory environments. The University of Kassel is also involved.

Portrait of Mohamed Benyoucef. Image: Sonja Rode.
Mohamed Benyoucef is the spokesman for the Kassel group.

Everyone knows them from home, where they live out their lives in remote sockets and send the home Wi-Fi to corners of the apartment that would otherwise be unreachable with the router alone: Repeaters. When cleverly placed, these small devices considerably extend the range of data transmission.

Many scientists in Germany are also researching repeaters. However, it is not repeaters that you can buy for a few euros at the electronics store, but much more complex quantum repeaters that scientists are focusing on. In the new research project "Quantenrepeater.Net (QR.N)", which is funded by the Federal Ministry of Education and Research, a total of 42 partners from research and industry want to make further progress in the research and establishment of quantum networks.

The Institute for Nanostructure Technology and Analytics (INA) at the University of Kassel is involved with two sub-projects. The spokesperson for the Kassel group is Prof. Dr. Mohamed Benyoucef, who also heads the sub-project "Telecom C-band InP-based quantum dot structures and quantum dot molecules". The second sub-project "Diamond-based photonic nanostructures with coupled color centers" is led by Prof. Dr. Cyril Popov.

In the future, quantum networks could be of crucial importance for free societies and the protection of our critical infrastructure - just think of the rapidly increasing number of IT sabotage, espionage and hacker attacks. Quantum networks would offer a whole new level of security here. This is because the quantum physics on which such a network is based makes them extremely secure against espionage or sabotage. Quantum repeaters, which allow information to be transmitted securely even over long distances and thus enable quantum networks, therefore make an important contribution to setting up a quantum-secure IT infrastructure. They also offer the prospect of secure networking for future quantum computers.

However, this is of course a challenging undertaking. "The realization of quantum repeaters and, in perspective, end-to-end quantum networks represents an enormous technical challenge," explains Christoph Becher, Professor of Quantum Optics at Saarland University and spokesperson for the research network. The quantum states for communication in the quantum network must be generated with high quality, temporarily stored and transmitted with as little loss as possible. However, in order to turn a simple connection between two points into an entire network, nodes are needed that temporarily store these quantum states and ensure transmission to the next node - repeaters.

The aim is to set up intermediate nodes between two end points of a network connection, install quantum memories at these nodes and carry out gate operations. This should achieve a quantum advantage in transmission and enable error correction for more powerful quantum repeater protocols.

Another research question that the partners in "QR.N" are addressing concerns the hardware on which the quantum network is based. This is because there is as yet no hardware basis that has become established in research. Quantum memories and quantum networks can be based on individual atoms and ions, semiconductor structures, artificial atoms in diamonds and rare earth atoms. The consortium therefore also wants to search for cross-platform methods and protocols and combine different hardware platforms into hybrid systems in order to ultimately achieve hardware-independent quantum nodes. The participating institutions also want to support existing "classic" communication networks with methods of quantum entanglement, the basic principle of quantum technology.

A declared aim of the project consortium is to develop the basis for establishing "quantum-secured communication" in Germany in a few years' time. This is of great importance to society, particularly in terms of IT security and the protection of critical infrastructure.

 

Background:

The "Quantenrepeater.Net (QR.N)" project was launched on January 1, 2025 and is being funded by the Federal Ministry of Education and Research with a total of 20 million euros over three years. A total of 42 research institutions and companies are working together to develop the basic building blocks of a quantum network structure based on quantum repeaters.