Satellite-to-Ground QKD in Urban Environment: A Comparative Analysis of Small-Sized Optical Ground Stations

This paper presents an in-depth satellite-to-ground Quantum Key Distribution (QKD) feasibility analysis between a Low Earth Orbit (LEO) satellite and a 0.28 m small-sized Optical Ground Stations (OGSs) located in urban areas, over nighttime. Both Prepare & Measure (P&M) and Entanglement (ENT)- based QKD protocols are employed and compared in terms of distilled key bits. The performance of various detection setups and environmental conditions including different wavelengths (1550 nm and 810 nm) as well as different types of detectors (Avalanche and Superconducting Nanowires) is simulated. The results are compared to those obtained when OGSs with much larger receiver apertures are placed in rural environment. Our analysis delivers a framework examining the parameters affecting the QKD satellite downlink, and also provides a thorough theoretical framework for the employment of small-sized OGSs in urban environments.