Secure quantum key distribution over 40 km of fiber with a pulsed heralded single photon source
Alexandre Soujaeff, Shigeki Takeuchi, Keiji Sasaki, Tsuyoshi Nishioka, Toyohiro Tsurumaru, Toshio Hasegawa, Mitsuru Matsui · 2007
Despite technically successful experiments, most of current quantum key distribution (QKD) systems based on the original BB84 protocols are insecure. The reason is the usage of weak coherent pulses (WCP) as pseudo single photon source (SPS), which allows an eavesdropper to get full information on the key in presence of high optical losses on the transmission channel. To overcome this problem, we have developed a pulse heralded single photon source (HSPS), which we have used for QKD over 40 km of fiber.