Fig. 1. Test of photon polarization state change

Fig. 2. Probability distribution of time used corresponding to the QBER over 2.5% induced by polarization changes

Fig. 3. Structure of fast polarization feedback system

Fig. 4. Structure of the feedback module

Fig. 5. Operation efficiencies of different simulation algorithms. (a) Hill-climbing algorithm; (b) simulated annealing algorithm

Fig. 6. Judging process whether feedback is finished or not

Fig. 7. Coding rate with or without adaptive algorithm

Fig. 8. Coding rate of the quantum communication over 40.5 km fiber link (including 15 km aerial fiber) in Beijing

Fig. 9. Polarization feedback time probability distribution in Hefei

Fig. 10. Coding rate of the quantum communication over 68 km aerial fiber link in Hefei