How to choose the best QKD network technology: three different satellite based scenarios compared

Abstract

Quantum cryptography promises unconditionally secure communication. Today, there exists a vast array of different QKD protocols that claim to offer security. However, looking in more detail, many subtleties lead to different security levels, or in the worst-case to no security at all. Here, we introduce the most crucial QKD security properties, ranging from different attack schemes to actual implementation security considerations. We present three different QKD use-cases with different network topologies: one trusted-node-based scenario (BB84 decoy) and two trusted-node-free (entanglement-based BBM92 and twin-field QKD). Using our, in cooperation with the European Space Agency (ESA), in-house developed simulations package, we simulate all relevant performance parameters, including the expected finite secret-key-rate. Furthermore, we assess all simulated QKD protocols' applicability to satellite-based QKD networks and identify essential technologies. Interestingly, not the single-photon detection modules are the key drivers in terms of secure-key-rate performance, but the optical sending and receiving telescopes.

Exploiting potentialities for space-based quantum communication network: downlink quantum key distribution modelling and scheduling analysis

“…Though improving the experimental settings (e.g. employing larger lens) is regarded as beneficial for the transmission efficiency, a tradeoff between cost and efficiency to determine the space-qualified parameters exists from a practical engineering perspective [39][40][41]. Recently, a state-of-the-art QKD system installed in a geosynchronous orbit (GEO) satellite [42,43] is considered to increase work time, while the yields of long-term SatQKD in the daytime are unclear owing to the unpredict solar radiation [44].…”

Exploiting potentialities for space-based quantum communication network: downlink quantum key distribution modelling and scheduling analysis

“…To overcome this issue, one can one can either upgrade the QKD system to achieve a faster data collection rate or spend more time to gather data. As for the former, improving the experimental settings (e.g., employing larger lens) is regarded as beneficial for a lower downlink channel loss, while from a practical engineering perspective, a trade-off between cost and efficiency to determine spacequalified parameters exists [30,31,32]. The latter, a state-of-the-art QKD system installed in a geosynchronous orbit (GEO) satellite [33,34] is considered to operate 24-hour QKD, while the yields of long-term SatQKD in the daytime are unclear owing to the unpredict solar radiation [35].…”