Aerospace Project QuNET: Testing Quantum Channels in Flight

Related Vendor

GGB Heilbronn GmbH

Researchers succeeded in measuring various quantum channels between an aircraft and a ground station, sending photons to an ion trap, and testing technologies for quantum key distribution. This flight experiment took place as part of the QuNET initiative, which develops technologies for quantum-secured communication.

The German Aerospace Center (DLR), the Max Planck Institute for the Science of Light (MPL), Friedrich-Alexander-Universität Erlangen (FAU), and the Fraunhofer Institutes for Applied Optics and Precision Engineering (IOF) and Heinrich Hertz Institute (HHI) have laid the foundation for a future quantum network. To achieve this, the partners tested quantum channels in flight and were now able to present the results to the Federal Ministry for Research, Technology, and Space (BMFTR). Quantum key distribution is particularly important for communication between governments and authorities, but also for protecting infrastructure and everyday data in the future. "We are working on practical solutions for satellite-based quantum communication, which can transmit quantum states over great distances and generate secure keys. In optical fibers, this is only possible over a few hundred kilometers. Quantum encryption via satellites, on the other hand, enables arbitrarily greater distances on Earth," explains Florian Moll from the DLR Institute of Communications and Navigation about the future technology. To overcome long distances, satellites, airplanes, or other mobile platforms are expected to become part of quantum networks in the future.

In the experiment, a DLR research aircraft from the Flight Experiments facility was used, equipped with an optical communications terminal. The aircraft served as a mobile node in a quantum network and established a connection to a ground station. The ground receiving station, in this case, is a mobile container with an integrated receiving terminal, the QuBUS, from the Fraunhofer IOF.

Overcoming challenges

Individual photons are difficult to handle: for quantum communication, they must be generated with high quality and clearly detected even under strong external disturbances. Additionally, the wavelength of the photons must be precisely adjusted for the best possible results. For the current experiment, several research flights over Erlangen took place because the ion trap is set up in the local MPL laboratory. The light particles from the aircraft were guided into a fiber-optic cable at the ground station. The fiber then led to the measuring devices of the various experiments. The states of the "flying" particles could be detected in measurements at the ion trap – which was one of the experiment's goals. This communication technology can also be used, for example, to connect quantum memories or quantum computers in a future quantum network.

Satellite-based quantum communication

Systems for conducting experiments on Quantum Key Distribution (QKD) were connected in both the aircraft and the ground station in Erlangen (Germany). These are groundbreaking for satellite-based quantum communication: a system for clock-channel-free Quantum Key Distribution was tested. Additionally, photons from an entanglement source on the ground were detected. Channel measurements and component tests for QKD systems with novel and flexibly configurable protocols also provided important insights for further developments in secure communication of the future. (se)