Experimental realization of quantum cryptography communication in free space

作     者：WANG Chuan1, ZHANG Jingfu1, WANG Pingxiao1, DENG Fuguo1, AI Qing1 & LONG Guilu1,2 1. Department of Physics, Key Laboratory for Quantum Information and Measurements, Tsinghua Univer- sity, Beijing 100084, China 2. Center for Atomic and Molecular NanoSciences, Tsinghua University, Beijing 100084, China 

作者机构：Department of Physics Key Laboratory for Quantum Information and Measurements Tsinghua University Beijing China Atomic and Molecular NanoSciences Tsinghua University Beijing China 

出 版 物：《Science China(Physics,Mechanics & Astronomy)》 (中国科学：物理学、力学、天文学（英文版）)

年 卷 期：2005年第48卷第2期

页      面：237-246页

核心收录：

学科分类：07[理学] 070104[理学-应用数学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0704[理学-天文学] 0701[理学-数学] 

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.10325521 and 60433050) China Postdoctroal Science Foundation the National Foundation Research Program(Grant No.001CB309308). 

主　　题：quantum key distribution, free space, linear optics, faint pulses. 

摘      要：Utilizing linear optical devices, the principle of B92 quantum key distribution (QKD) protocol is demonstrated in free space with a distance of transmission of 2.2 meters. The faint laser pulses with 650 nm wavelength are used as the single photon sources. The experimental results show that the eavesdropping behavior in the signal transmission can be detected. We also discuss the problems and solutions in using the quantum cryptography communication practically. It is pointed out that one of the approaches to increasing the distance of the quantum communication is to overcome the attenuation of the single photon in transmission. This could not be solved by the use of single photon source, and new quantum communication protocols are needed to solve these problems.