Experimental Long-Distance Decoy-State Quantum Key Distribution Based On   Polarization Encoding
  We demonstrate the decoy-state quantum key distribution (QKD) with one-way quantum communication in polarization space over 102km. Further, we simplify the experimental setup and use only one detector to implement the one-way decoy-state QKD over 75km, with the advantage to overcome the security loopholes due to the efficiency mismatch of detectors. Our experimental implementation can really offer the unconditionally secure final keys. We use 3 different intensities of 0, 0.2 and 0.6 for the pulses of source in our experiment. In order to eliminate the influences of polarization mode dispersion in the long-distance single-mode optical fiber, an automatic polarization compensation system is utilized to implement the active compensation. 
Cheng-Zhi Peng, Jun Zhang, Dong Yang, Wei-Bo Gao, Huai-Xin Ma, Hao   Yin, He-Ping Zeng, Tao Yang, Xiang-Bin Wang, Jian-Wei Pan