Entanglement-based QKD over LEO satellite-to-ground time-varying atmospheric channel

Abstract

For enabling and realizing long-haul Quantum Key Distribution (QKD), satellite communication infrastructure is exploited to deliver symmetric encryption keys to ground segments. In this direction the European Quantum Communication Infrastructure (Euro-QCI) initiative, supported by the European Space Agency (ESA), aims to build a secure quantum communication network that will span across the EU. In this framework, ESA has selected three observatories in Greece to support European activities in optical communications and QKD systems. In this study, a QKD feasibility analysis between a LEO satellite constellation (100 satellites) and the three selected Optical Ground Stations (OGSs) in Greece, using an entangled based QKD protocol is presented. This contribution focuses on the performance evaluation and the applicability validation of an entanglement-based QKD system in a pragmatic regional segment of Euro-QCI. The time varying atmospheric channel is modeled taking into account the joint cloud coverage of the OGSs, the turbulence, the pointing errors and the solar background radiance. The performance of the regional entangled-based QKD system is validated in terms of annual availability as well as the number of shared distilled key bits between the ground stations per year.