Scenario analysis for performance evaluation of free space quantum and classical communication channels

In order to asses free space optical links, using a Cassegrain telescope, for both classical (i.e. coherent and direct detection) and quantum (coherent, Dolinar-Kennedy system) several scenarios were analyzed. This analysis was conducted through a software tool that uses some specific parameters imposed by the environmental condition and hardware used, such as: pointing and tracking errors, turbulence, modulations schemes, and visibility, among others; in order to obtain the general performance parameters of the simulated link, such as: bit error rate and the photons number. The software developed allows the user to produce useful way to assess the possible success of the implementation of the free space optical link, or a way to identify phenomena that might suggest hardware adjustments to improve the overall performance of the system. Results allow the revision of the expected link performance for a quantum key distribution system; although it is possible to use it for general optical quantum communications systems.