QuNET Project: Germany’s in Hybrid Quantum Key Distribution
German Fibre and Mobile Networks Reach Historic Hybrid Quantum Key Distribution
QuNET Project
Germany made a major step towards secure digital communication by proving quantum key distribution (QKD) works over hybrid and mobile networks. QuNET researchers accomplished this. QuNET is preparing to expand these systems from regional test locations to a countrywide quantum network linking many German cities.
Quantum Security Strengthens Technological Sovereignty
This accomplishment shows Germany's commitment to cybersecurity technical sovereignty and advances quantum-secured networks. Due to developing computer technologies' limitations to classical encryption, quantum communication is growing in importance.
QKD uses quantum physics to build secure digital keys. Most QKD signals contain only a few photons, therefore keys cannot be copied without detection. This advancement is supported by the German Federal Ministry for Research, Technology, and Space, which has donated €125 million (US $145 million) to QuNET.
QuNET's key partners include Fraunhofer IOF, Fraunhofer HHI, Max Planck Institute for the Science of Light, Friedrich-Alexander University Erlangen-Nuremberg, and DLR Institute of Communication and Navigation.
Combining Protocols and Links Several experiments in the latest study show significant gains in integrating different technologies into a workable system. Dr. Matthias Goy of Fraunhofer IOF said the team proved that “different QKD protocols and link types can be integrated into a functioning overall network”. No global publication has shown this integration heterogeneity.
Over the past four years, the consortium has completed several practical tests to prove its practicality under difficult conditions:
Two federal agencies had the first quantum-secured virtual conference in 2021. In 2023, Jena demonstrated ad hoc point-to-point connectivity.
The Berlin municipal fibre network transmitted personal data safely in 2024.
In 2025, researchers delivered quantum data to a DLR research plane to check mobile compatibility.
Each benchmark revealed how effectively the system worked in increasingly complex and realistic circumstances.
Mobility in Secure Networks
The researchers struggled with stability because quantum signals degrade quickly, especially in turbulent air. The team tried many Jena systems that employed free-jet technology to convey keys through air columns to tackle this problem.
Creating secure long-distance, transitory, and mobile channels requires this method. Researchers can also bridge communication gaps in locations lacking fibre infrastructure.
Hardware and software integration was key. The networks must combine future satellite nodes, fibre, and free-space optical communication. Tests show that diverse architectures can coexist without compromising system security.
The effort helps Germany develop technological understanding and reduce dependency in a future security-critical subject, Dr. Goy added. These developments demonstrate progress towards creating a scalable, future-proof system that can adapt to quantum hardware.
Moving to a National Hybrid Network
The next critical step is creating a hybrid national quantum network connecting Berlin, Jena, Erlangen, and Oberpfaffenhofen beyond local testing. This massive concept uses fibre lines, free-space connectivity, and optical ground stations for satellite communications.
This connection prepares the shift from small test sites to scalable networks, Dr. Goy said.
The long-term goal of QuNET is to build a sovereign quantum network for infrastructure, business, and government. This rollout establishes a secure communication age across Europe and marks a major step from experimentation to deployment.
