NEC Completes World's Longest Single-Photon Transmission Over 100Km

NEC, the Telecommunications Advancement Organization of Japan (TAO) and the Japan Science and Technology Corporation completed a 100-km-long single-photon transmission using a quantum cryptography system over low cost optical fiber. The companies said their demonstration paves the wave for quantum cryptography transmissions in metropolitan optical networks. The system uses a low-noise photon receiver developed jointly by NEC and the Imai Quantum Computation Information Project, and a high performance transmitter developed by NEC and TAO. The transmitter is equipped with a filter that can purify the single-photon spectrum.
http://www.nec.co.jp/press/en/0307/0401.html