Miniaturized QKD Satellite aims to demonstrate first Quantum Key Distribution between CubeSat and Ground Station:
In early May 2026, the approximately ten-kilogram small satellite QUBE II was launched into space aboard a Falcon 9 rocket and successfully commissioned after about one hour. The objective is the demonstration of full Quantum Key Distribution (QKD) between a microsatellite (CubeSat) and a ground station – an important step toward quantum-secure communication. The project “Quantenschlüsselübertragung von einem CubeSat zum Boden (QUBE II)” is a collaborative research initiative funded by the Bundesministerium für Forschung, Technologie und Raumfahrt (BMFTR). In addition to the consortium coordinator OHB System AG, partners include the Zentrum für Telematik e.V., the Deutsche Zentrum für Luft- und Raumfahrt (DLR), the Ludwig-Maximilians-Universität München and the Friedrich-Alexander-Universität Erlangen-Nürnberg. QUBE II builds on the successes of the predecessor project “Quantenschlüsselverteilung mit Cube-Sat (QUBE)” and combines state-of-the-art Quantum Optics with high-precision laser communication.
In the predecessor project QUBE, novel technologies for generating Quantum Keys were already integrated into a CubeSat platform and combined with high-performance optical communication systems. These miniaturized Quantum Components are tested under the extreme conditions of space – such as strong temperature variations and radiation exposure – to evaluate their functionality and suitability for future QKD applications. To enable full Quantum Key Distribution using the technologies developed in QUBE, these systems were further developed and extended with additional components within the QUBE II project. A key challenge in Quantum Key Generation is channel loss between the satellite and the ground station. In QUBE II, this is addressed in part by increasing the output aperture of the telescope used for transmitting Quantum Signals. In addition, an optical link between the ground station and the small satellite – a so-called uplink – is being established for the first time. This is necessary because the employed QKD protocols require not only Quantum Signals but also a bidirectional classical optical communication link with high data rates. For this purpose, the OSIRIS4CubeSat terminal developed by the DLR is being extended, among other things, with a data receiver.
The QUBE II platform is based on the CubeSat architecture already used in the predecessor project, which enables a cost-efficient, standardized, and modular design. Due to the enlarged telescope aperture and additional functionalities, the satellite size increases from the original 3U configuration to 6U. With this, QUBE II contributes to the further development of satellite-based Quantum Communication.
Source references: https://www.dlr.de/en/kn/research-transfer/projects/qkd-quantum-technology-for-secure-communication/qube-ii-quantum-key-distribution-with-cubesat; https://www.forschung-it-sicherheit-kommunikationssysteme.de/projekte/qube‑2