Environmental effects on classical and quantum free space optical communication

Quantum internet required the transmission of both quantum key distribution (QKD) through Quantum free space optic (QFSO) channel and an encrypted message through the classical free space optic (CFSO) channel. However, those channels are subjected to environmental parameters. The aim of this work is to study the joint effects of those parameters on CFSO and QFSO through the evaluation of bit error rate (BER) and QKD rate. It comes out that for a given environment roughness under LSO (line of sight) and transmitters distance, the increasing of temperature and wind velocity will not necessary increase the average BER if they are not associate with appropriate fluctuations. The increasing environment roughness and transmitters distance leads to increasing the average BER. Moreover, for a given environment roughness and transmitters distance, there is a range of temperature within which quantum mutual information between Eve and Bob is reduced; which leads to improve QKD Rate.