The €6 million German effort aims to move quantum communications beyond point-to-point systems and into real-world multi-node infrastructure.
A new German research initiative aims to push quantum networks beyond laboratory demonstrations and simple bilateral links.
The three-year QCyber project, supported by 6 million euros from the German Federal Ministry for Research, Technology and Space, will develop and field test secure quantum applications over a fiber-optic network in Stuttgart, connecting up to six nodes over a distance of 20 kilometers.
The consortium, coordinated by Professor Stephanie Bartz from the University of Stuttgart, brings together partners from academia and industry to investigate how quantum communications can work in realistic multi-user environments, a scenario that reflects how secure digital infrastructures operate in real life.
From two-party links to multi-user quantum networks
Most experimental quantum networks demonstrated so far focused on secure communication between two participants.
Although these systems validate core principles such as quantum key distribution, they do not reflect the complexity of real-world communication systems where multiple actors exchange information simultaneously.
QCyber aims to address that gap. Researchers will design and evaluate quantum applications that allow multiple users to securely participate within the same network.
This includes protocols that enable secure group-based communication, collaborative decryption schemes, and distributed processing models designed for networked environments.
This effort comes at a critical time for cybersecurity. Advances in quantum computing threaten to undermine widely used traditional encryption standards.
At the same time, quantum communications offers fundamentally different security guarantees rooted in quantum physics, such as the ability to detect eavesdropping.
By focusing on multi-node architectures, the Stuttgart-led team will consider how quantum networks can scale and interoperate with existing digital infrastructure.
Testing quantum communications in real fiber networks
This project is unique in that it focuses on deployment under operational conditions rather than a pure laboratory environment.
The researchers will establish a fiber-optic network spanning Stuttgart’s Veingen and City Center campuses, forming a testbed with up to six connected nodes. Additional test links will be provided by Nokia.
The purpose is twofold. To evaluate the performance of newly developed hardware and software components and to evaluate the security of these systems once they are integrated into the broader communications environment.
The researchers will also study how quantum communications can be incorporated within traditional cybersecurity architectures, an issue that is likely to be central to future commercial deployments.
Industry involvement forms part of the testing strategy. The workshops held at ARENA2036 will include representatives from sectors such as manufacturing, mobility and cloud services.
Discussions will explore potential applications ranging from secure links between vehicles and infrastructure and securing industrial control systems to securing sensitive data exchange between businesses.
Expanding the scope of quantum applications
QCyber goes beyond secure messaging to explore a variety of quantum applications that rely on coordinated actions between multiple parties.
Among them are protocols that allow information to be distributed in such a way that decryption requires cooperation between designated participants, reducing the risks associated with single points of failure.
The researchers will also explore secure multiparty computing approaches within quantum networks, a foundational feature for future quantum-based cloud computing services.
Another line of research concerns quantum-enabled electronic voting systems that provide verifiability while maintaining voter anonymity.
Although such systems are still in the early stages of development, they point to broader ambitions to scale quantum communications from niche security tools to infrastructure-level services.
Research consortium and schedule
QCyber brings together three laboratories at the University of Stuttgart: the Institute for Functional Materials and Quantum Technology, the Institute for Semiconductor Optics and Functional Interfaces, and the Institute for Information Security, with partners at the University of Würzburg and the Technical University of Berlin.
Industry participation includes Swabian Instruments, a spin-off from Stuttgart. Nokia and ARENA2036 are participating as associate partners.
The project will run from early 2026 until the end of 2028. By combining applied research and field deployment, the consortium aims to generate practical insights into how scalable quantum networks and quantum applications can form part of Europe’s future secure digital infrastructure.
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