Aerospace laser communications technology as enabler for worldwide quantum key distribution

Abstract

A worldwide growing interest in fast and secure data communications pushes technology development along two lines. While fast communications can be realized using laser communications in fiber and free-space, inherently secure communications can be achieved using quantum key distribution (QKD). By combining both technologies in a single device, many synergies can be exploited, therefore reducing size, weight and power of future systems. In recent experiments we demonstrated quantum communications over large distances as well as between an aircraft and a ground station which proved the feasibility of QKD between moving partners. Satellites thus may be used as trusted nodes in combination with QKD receiver stations on ground, thereby enabling fast and secure communications on a global scale. We discuss the previous experiment with emphasis on necessary developments to be done and corresponding ongoing research work of German Aerospace Center (DLR) and Ludwig Maximilians University Munich (LMU). DLR is performing research on satellite and ground terminals for the high-rate laser communication component, which are enabling technologies for the QKD link. We describe the concept and hardware of three generations of OSIRIS (Optical High Speed Infrared Link System) laser communication terminals for low Earth orbiting satellites. The first type applies laser beam pointing solely based on classical satellite control, the second uses an optical feedback to the satellite bus and the third, currently being in design phase, comprises of a special coarse pointing assembly to control beam direction independent of satellite orientation. Ongoing work also targets optical terminals for CubeSats. A further increase of beam pointing accuracy can be achieved with a fine pointing assembly. Two ground stations will be available for future testing, an advanced stationary ground station and a transportable ground station. In parallel the LMU QKD source size will be reduced by more than an order of magnitude thereby simplifying its integration into future free-space optical communication links with CubeSats.

Hardware routed quantum key distribution networks

“…LC has been implemented to facilitate QKD, as shown in [23]. The high‐level design of the system used in [23] is given in Figure 2. We now discuss the proposed changes to make LC compatible with the proposed system.…”

“…The proposed system introduces minor changes to the existing system to facilitate classical labelling of photons. The first three steps for line-of-sight link acquisition remain the same as the original system using the WFoV camera, IMU, 4 Quadrant diode (4QD), Digital signal processor, etc (refer [23]). We discuss the changes at the aircraft terminal, followed by the changes at the ground station.…”

Modular FSO optical system design for classical and quantum optical communication systems

“…Therefore, the optical system of a laser terminal shares high synergies for both applications (classical laser communications and quantum communications). 10 Within the project OSIRISv3, a laser terminal for LEO satellites is developed. Because of its high modularity, this concept forms the basis for a breadboard version of the laser terminal for demonstration of QKD secured data transmission in the framework of the project QuNET.…”

Effects of Saturation for High-Throughput Satellite Buses

“…Take, for instance, the attitude and orbit control subsystem (AOCS) of a satellite for high-speed optical communication. The required pointing accuracy for demonstrating multiple high-speed laser communication links is in the range of 1 µrad to 1 mrad [1], compared to the 10 to 100 mrad required for satellites using radio-frequency links [2].…”