  Satellite-based quantum cryptography has already been demonstrated using
discrete variable technology. Nonetheless, there is great interest in using
weak coherent pulses to perform quantum key distribution (QKD) in the
continuous variable (CV) paradigm. In this work, we study the feasibility of
performing coherent-state CV-QKD via the satellite-to-ground channel. We use
numerical methods to simulate atmospheric turbulence and compare the results
with ground-based experimental data so as to confirm the validity of our
approach. We find the results obtained from the numerical simulations agree
well with the experimental data and represent an improvement over the
state-of-the-art analytical models. Using the simulation results we then derive
QKD key rates and find that useful non-zero key rates can be found over a
limited range of zenith angles. Determination of QKD key rates using
experimentally validated simulations of low-zenith-angle atmospheric channels
represents an important step towards proving the feasibility of real-world
satellite-to-Earth CV-QKD.

Quantum Physics