Secure quantum applications for real-world networks

The new QCyber joint research project is developing secure applications in quantum networks with multiple users. The methods will be tested in a real fibre-optic network in Stuttgart with up to six nodes and over distances of up to 20 km. The project involves three universities and is coordinated by Professor Stefanie Barz at the University of Stuttgart. QCyber is funded by the German Federal Ministry of Research, Technology and Space (BMFTR) with six million euros over three years.

When it comes to secure data transmission, the rapid development of quantum technologies we are seeing today is leading to an interesting stalemate. On the one hand, quantum computers will make it possible to crack conventional encryption methods. On the other hand, quantum communication promises a level of security against eavesdropping that is fundamentally unattainable by other means.

"Quantum networks studied so far typically connect only two users. But in practice, often multiple parties need to communicate securely at the same time," says Professor Stefanie Barz of the University of Stuttgart. This is where QCyber comes in: the project, led by Barz, develops and tests quantum applications in networks with multiple users. These are not limited to pure communication but encompass a wide range of applications.

The applications being developed aim to open up entirely new possibilities. For example, the team will develop a secure quantum-based method for communication among multiple users. This is directly relevant for diplomacy and finance, not least because it can also guarantee anonymity. Another method allows information to be distributed such that it can only be decrypted through collaboration among multiple parties. And "quantum e-voting" could in future enable verifiable, anonymous elections with maximum trustworthiness. Finally, secure computing in networks is the foundation for future quantum-based cloud computing. "With this fundamental yet application-oriented research programme, QCyber aims to make an important contribution to strengthening and securing technological sovereignty in future IT security in Germany and Europe," says Barz.

A central element of QCyber is testing under real-world conditions. To this end, a campus-wide fibre network is being set up in Stuttgart, which also connects the Campus Vaihingen with the Campus City Center. Nokia, as an associated partner, is providing an additional test link. These tests will assess the practical viability of the hardware and software developed by the QCyber partners. At the same time, the security of the implementation will be analysed and QCyber researchers will investigate how quantum applications can be integrated into conventional cybersecurity systems.

Network integration is also at the heart of workshops with industry representatives, held at ARENA2036, the research centre for the mobility of the future on the Vaihingen campus. There, potential end users are involved early on to identify possible deployment scenarios — from secure vehicle-to-infrastructure communication and protection of production networks in ‘smart factories’ to secure transmission of sensitive data between companies, suppliers and cloud services.

Joint research project with partners from research and industry
QCyber is a collaboration of three institutes at the University of Stuttgart — Institute for Functional Matter and Quantum Technologies (FMQ), Institute for Semiconductor Optics and Functional Interfaces (IHFG), Institute for Information Security (SEC) — with the University of Würzburg and TU Berlin. The industry partner is Swabian Instruments, founded as a spin-off from the University of Stuttgart. Nokia and ARENA2036 e.V. are involved as associated partners. The consortium is coordinated by Professor Stefanie Barz at the University of Stuttgart. The project is funded by the German Federal Ministry of Research, Technology and Space (BMFTR) with six million euros and runs from early 2026 to the end of 2028.