Optimised finite key for satellite up-link entangled quantum key distribution

arXiv:2611.03788v1 Announce Type: new Abstract: Entanglement-based quantum key distribution from ground to satellite has been proposed as a scalable primitive for global quantum networks and will be demonstrated as part of the imminent QEYSSat mission. Both theoretical studies and experimental emulations have shown that a significant asymptotic key rate can be expected. In this work we investigate this scenario with a more rigorous security analysis taking into account the finite size effects that arise from short block lengths common in satellite transmission. Our findings suggest a slight alteration of the optimal source operation when informed by finite statistics as opposed to the asymptotic regime, notably that the pump power should be slightly lowered.