Scheduling of space to ground quantum key distribution

Abstract

Satellite-based platforms are currently the only feasible way of achieving intercontinental range for quantum communication, enabling thus the future global quantum internet. Recent demonstrations by the Chinese spacecraft Micius have spurred an international space race and enormous interest in the development of both scientific and commercial systems. Research efforts so far have concentrated upon in-orbit demonstrations involving a single satellite and one or two ground stations. Ultimately satellite quantum key distribution should enable secure network communication between multiple nodes, which requires efficient scheduling of communication with the set of ground stations. Here we present a study of how satellite quantum key distribution can service many ground stations taking into account realistic constraints such as geography, operational hours, and most importantly, weather conditions. The objective is to maximise the number of keys a set of ground stations located in the United Kingdom could share while simultaneously reflecting the communication needs of each node and its relevance in the network. The problem is formulated as a mixed-integer linear optimisation program and solved to a desired optimality gap using a state of the art solver. The approach is presented using a simulation run throughout six years to investigate the total number of keys that can be sent to ground stations.

Spooky action at a global distance: analysis of space-based entanglement distribution for the quantum internet

“…Including these extra elements would introduce extra attenuation factors (see, for e.g., section 2.1.1.4 of ref. 37 and refs 96,97 ), which would increase the overall satellite-to-ground transmission loss (see refs 78,98 for an analysis of satellite-to-ground quantum key distribution in a localized area that incorporates local weather conditions). We also point out that, especially in the daytime, background photons (e.g., from the sun) can reduce the fidelity of the distributed entangled pairs, because the receiver will collect those background photons in addition to the signal photons from the entanglement source.…”

“…We do not consider such an assignment strategy here (see ref. 98 for work in this direction), except for when there is a ground-station pair that has only one satellite in view, but that satellite is in range of several other ground stations. In this case, we assign that satellite to the "lone" ground-station pair even if the loss is higher than another possible assignment of that satellite.…”

QUARC: Quantum Research Cubesat—A Constellation for Quantum Communication

“…It is found that, in general, southern regions offer a more consistent long-term average rate of key transfer but with isolated regions further north benefiting from long overnight dark periods and minimal cloud cover during some winter months. The mission analysis results presented offer indicative levels of performance for gateways distributed across the UK; however, it is recommended that mission-specific analysis be carried out for different topologies [41].…”

“…More satellites result in a greater level of expected coverage and secure key, while more gateways result in a higher probability of contact being made and a smaller amount of key data being received at each individual gateway. Here, we have chosen not to focus on the key management and scheduling problems but we refer the reader to recent works on these topics [40,41].…”

Design and Performance of Relay-Assisted Satellite Free-Space Optical Quantum Key Distribution Systems

“…Satellite-based QKD can enable secure network communications between multiple ground stattions if there is an efficient communication scheduling. In [16], a study on how satellite-based QKD can service many ground stations taking into consideration realistic constraints such as geography, operational hour, and weather conditions has been presented. Recently, instead of using fixed ground stations, the world's first mobile quantum satellite station has been developed in China.…”