A novel polarization compensation method in free space quantum key distribution

With the increased significance of building a global secure information network, free space quantum key distribution provides a brand new approach of transmitting secure information between two distant parties based on quantum mechanics. However, the polarization state of single photon is vulnerable to the complicated atmospheric environment and may lead to failure of key distribution. Therefore an efficient polarization compensation method based on optical rotation effect is proposed. The fundamental-mode Gaussian beam is used as the emission source at the Alice's side which will attenuate the beam into single photon level. In order to demonstrate the effect of the new compensation method, the polarization degree is calculated at different wave length and various distances. The simulation results show that the optical rotation effect can be used to compensating polarization states.