The research of single photon acquisition probability based on the fundamental-mode Gaussian beam

Theoretical model of single photon acquisition probability is established for free-space quantum key distribution.The expression of single photon acquisition probability is deduced from the fundamental-mode Gaussian beam.The parameters that influence the single photon acquisition probability are the transmitter's tracking-pointing error,the far-field divergence angle,the link distance between transmitter and receiver and the receiver's antenna aperture.The single photon acquisition probability is analyzed in numerical simulation for the link between a ground station and a satellite in a low earth orbit and it is normally on the order of 10-3~10-5.