  Advances in satellite quantum communications aim at reshaping the global
telecommunication network by increasing the security of the transferred
information. Here, we study the effects of atmospheric turbulence in
continuous-variable entanglement distribution and quantum teleportation in the
optical regime between a ground station and a satellite. More specifically, we
study the degradation of entanglement due to various error sources in the
distribution, namely, diffraction, atmospheric attenuation, turbulence, and
detector inefficiency, in both downlink and uplink scenarios. As the fidelity
of a quantum teleportation protocol using these distributed entangled resources
is not sufficient, we include an intermediate station for either state
generation, or beam refocusing, in order to reduce the effects of atmospheric
turbulence and diffraction, respectively. The results show the feasibility of
free-space entanglement distribution and quantum teleportation in downlink
paths up to the LEO region, but also in uplink paths with the help of the
intermediate station. Finally, we complete the study with microwave-optical
comparison in bad weather situations, and with the study of horizontal paths in
ground-to-ground and inter-satellite quantum communication.
