  Airborne quantum key distribution (QKD) is now becoming a flexible bond
between terrestrial fiber and satellite, which is an efficient solution to
establish a mobile, on-demand, and real-time coverage quantum network.
Furthermore, When the aircraft is flying at a high speed, usually larger than
0.3 Ma, the produced boundary layer will impair the performance of
aircraft-based QKD. The boundary layer would introduce random wavefront
aberration, jitter and extra intensity attenuation to the transmitted photons.
However, previous airborne QKD implementations only considered the influences
from atmospheric turbulence and molecular scattering, but ignored the boundary
layer effects. In this article, we propose a detailed performance evaluation
scheme of airborne QKD with boundary layer effects and estimate the overall
photon transmission efficiency, quantum bit error rate and final secure key
rate. Through simulations and modeling, in our proposed airborne QKD scenario,
the boundary layer would introduce 3.5dB loss to the transmitted photons and
decrease 70.7% of the secure key rate, which shows that the aero-optical
effects caused by the boundary layer can not be ignored. With tolerated quantum
bit error rate set to 10%, the suggested quantum communication azimuth angle
between the aircraft and the ground station is within 60 degrees. Moreover, the
optimal beacon laser module and adaptive optics module are suggested to be
employed to improve the performance of airborne QKD system. Our detailed
airborne QKD evaluation study can be performed to the future airborne quantum
communication designs.
