Extended Data Fig. 2: QBER contribution of noise and satellite elevation angle as functions of time.
From: Microsatellite-based real-time quantum key distribution
The transmitted vacuum state allows for the assessment of the polarization-independent QBER arising from factors such as background noise. In urban environments, background noise is a dominant contributor to the QBER, particularly at low satellite elevation angles where received photon counts are reduced. This impact varies depending on ground station location, time of day, and weather conditions. Employing spectral filtering with narrower linewidth and spatial filtering with smaller field of view can further mitigate this issue.
