Fig. 1: Using multiple satellites to connect distant ground stations.
From: Simulating quantum repeater strategies for multiple satellites
a Using three satellites SA, SB, and SC to connect ground stations A and B (separated by a ground distance d allows reaching distances beyond the horizon of a single satellite. The positioning of the satellites is a new parameter to optimize in this scenario. b Total loss when trying to establish an entangled link between the ground station A and SC with an entangled pair source at SA. SA@x% denotes that satellite SA is positioned vertically above the point at x% of the total ground distance. With three satellites one can avoid sending qubits through the atmosphere at a very shallow angle by positioning the outer satellites closer to the ground stations. Orbital height h = 400 km, divergence angle θd = 3 μrad.
