Abstract
Global quantum communications will enable long-distance secure data transfer, networked distributed quantum information processing, and other entanglement-enabled technologies. Satellite quantum communication overcomes optical fibre range limitations, with the first realisations of satellite quantum key distribution (SatQKD) being rapidly developed. However, limited transmission times between satellite and ground station severely constrains the amount of secret key due to finite-block size effects. Here, we analyse these effects and the implications for system design and operation, utilising published results from the Micius satellite to construct an empirically-derived channel and system model for a trusted-node downlink employing efficient Bennett-Brassard 1984 (BB84) weak coherent pulse decoy states with optimised parameters. We quantify practical SatQKD performance limits and examine the effects of link efficiency, background light, source quality, and overpass geometries to estimate long-term key generation capacity. Our results may guide design and analysis of future missions, and establish performance benchmarks for both sources and detectors.
Highlights
Quantum technologies have the potential to enhance the capability of many applications[1] such as sensing[2,3,4], communications[5,6,7,8], and computation[9]
We describe in section ‘Finite key length analysis’ our satellite quantum key distribution (SatQKD) finite key analysis and examine the dependence of the secret key length (SKL) on different system parameters in subsequent sections
Important differences with fibre-based quantum key distribution (QKD) mean that small sample statistical uncertainties have a significant impact on the performance of satellite QKD
Summary
Quantum technologies have the potential to enhance the capability of many applications[1] such as sensing[2,3,4], communications[5,6,7,8], and computation[9]. A worldwide networked infrastructure of dedicated quantum technologies, i.e. a quantum internet[10], could enable distributed quantum sensors[11,12,13,14], precise timing and navigation[15,16,17], and faster data processing through distributed quantum computing[18]. This will require the establishment of long distance quantum links at global scale. Quantum repeaters may overcome the direct transmission limit but stringent performance requirements render them impractical by themselves for scaling to the intercontinental ranges needed for global scale-up[23]. Satellite-based free-space transmission significantly reduces the number of ground quantum repeaters required[24]
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