Emma Tien Hwai Medlock

Continuous variable quantum key distribution (CV-QKD) uses modulation of amplitude and phase of electromagnetic fields to encode information and shot noise limited detectors for decoding. The shot noise limited detection shows superior tolerance to noise and therefore a promising candidate for space-to-ground quantum communications, especially in daylight conditions. The parameters that affect the secure key generation rate of CV-QKD systems are the channel parameters- transmittance and uncalibrated noise (excess noise). On a typical static channel, such as an optical fibre link, the channel transmittance stays constant over a long period of signal transmission. On a dynamic channel, such as a Low Earth Orbit (LEO) based satellite to ground optical link, the transmittance of the channel varies concerning the zenith angle of the satellite.