The mission of QuNET is to make the communications of the future secure against eavesdropping and tampering.
The QuNET (Quantum Network) research initiative was founded in 2019 and is scheduled to run for seven years. Its goal is to use various technologies to create the foundations and in-house expertise for tap-proof, quantum-based communication networks in Germany and Europe, thus laying the foundation for secure communications of the future. It is also intended to lead the way for a future "quantum Internet." This is because the transmission of quantum states via optical fibers or free beams can also be used to efficiently interconnect quantum computers. The resulting network components must support various protocols and technologies in order to provide the necessary flexibility for future developments.
The QuNET research initiative is funded by the German Federal Ministry of Education and Research and led by Fraunhofer-Institut für Angewandte Optik und Feinmechanik (IOF), Jena. Other project partners are the Fraunhofer-Institut für Nachrichtentechnik (Heinrich-Hertz-Institut HHI), Berlin and the Max-Planck-Institut für die Physik des Lichts (MPL), Erlangen.
DLR is working on practical solutions for satellite-based quantum communication to securely and efficiently distribute keys over long distances. In optical fiber, this is only possible over a few 100 kilometers. Quantum encryption via satellite, on the other hand, enables arbitrarily larger distances on Earth.
Satellite-based quantum communication should enable the secure and efficient agreement of keys over long distances. In optical fibre, this is only possible over a few 100 kilometres. Quantum encryption via satellite, on the other hand, enables arbitrarily larger distances on earth.
The receiving terminal, also called the Bob terminal among researchers, receives and measures the quantum states. In free-space transmission, the wavefronts of the quantum states are distorted by the turbulent air layers in the atmosphere. Using state-of-the-art technology called adaptive optics, the wavefront distortions are detected and compensated for in real time by deformable mirrors.
The transmitting terminal, also called the Alice terminal among researchers, transmits light in the optical wavelength range for quantum communication. This space-qualified terminal is optimised for use on satellites.
DLR (CC-BY 3.0).
The quantum state transmission of the QuNET-alpha experiments takes place via a free-space channel starting from the roof of the Institute of Communication and Navigation to a receiving station 300m away on the grounds of the DLR site in Oberpfaffenhofen.
A researcher prepares the transmission terminal for quantum state transmission.
The DLR Institute of Communications and Navigation looks back on more than 20 years of research and groundbreaking results in the field of free-space optical data transmission. For QuNET, the scientists contribute their expertise in satellite-based quantum communication and are responsible for the free-space communication channel in which quantum states are transmitted between satellites and Earth. The signal quality and transmission efficiency requirements are among the major challenges. The satellite system will be equipped with various quantum sources to ensure optimal connectivity to a heterogeneous quantum network. This includes, for example, single photon sources, entanglement sources, or differently constructed transmitter modules for quantum key distribution.
When transmitting quantum states, it is important to achieve the highest possible signal quality. For this reason, the satellite-side transmitting and ground-side receiving optics must be designed in such a way that the quantum states are transmitted with as little interference as possible and the beam alignment can be made extremely precise. DLR's research also includes detailed channel characterization to quantify its influence on state transmission.
Record with 13,12 Terabits per second
Optical data transmission enables data transfers at very high data rates. The institute set the record together with ADVA Optical Networking in November 2017. It succeeded in transmitting 13.16 terabits per second over a distance relevant to satellites. Building on such work, the institute has also been researching satellite-based quantum communication for several years in collaboration with various partners.
Transmission of a quantum key from an aircraft for the first time
A special demonstration was achieved in 2011 by employees of the institute together with the Ludwig-Maximilians-Universität Munich. For the first time, a quantum key was successfully generated between an aircraft and a ground station - an important step towards worldwide tap-proof data communication. In 2015, the Erwin Schrödinger Prize of the Stifterverband was awarded for this work.
Funded by: Federal Ministry of Education and Research (BMBF)
Project duration: 2019-2026