Satellite-Based Communication for Phase-Matching Measurement-Device-Independent Quantum Key Distribution

This study investigates the feasibility of the phase-matching measurement-device-independent quantum key distribution (PM-MDI QKD) protocol proposed by Lin and Lütkenhaus for satellite-based quantum communication. The protocol's key rate, known to exceed the repeaterless PLOB bound, is evaluated in the asymptotic limit under noisy conditions typical of satellite communications, including loss-only scenarios. The setup involves two ground-based parties connected via fiber (loss-only or noisy) and a space-based third party linked to one of these two ground-based parties through free-space communication. Simulations using the elliptic-beam approximation model the average key rate (AKR) and its probability distribution (PDR) across varying zenith angles and fiber distances. Down-link free-space communication is assessed under day and night conditions, with intensity optimization for each graphical point. Dynamic configurations of satellite and ground stations are also considered. Results indicate that AKR decays more slowly under loss-only conditions, while PDR analysis shows higher key rates produce more concentrated distributions. These findings demonstrate the potential of PM-MDI QKD protocols for achieving reliable key rates in satellite-based quantum communication.