arXiv:quant-ph/0507110 · New Journal of Physics
Differential phase shift quantum key distribution experiment over 105 km fibre
Hiroki Takesue, Eleni Diamanti, Toshimori Honjo, Carsten Langrock, M. M. Fejer, Kyo Inoue, Y. Yamamoto
Abstract
We report a quantum key distribution experiment based on the differential phase shift keying (DPSK) protocol with a Poissonian photon source, in which secure keys were generated over >100 km fibre for the first time. We analysed the security of the DPSK protocol and showed that it is robust against strong attacks by Eve, including a photon number splitting attack. To implement this protocol, we developed a new detector for the 1.5 μm band based on frequency up-conversion in a periodically poled lithium niobate waveguide followed by an Si avalanche photodiode. The use of detectors increased the sifted key generation rate up to >1 Mbit s −1 over 30 km fibre, which is two orders of magnitude larger than the previous record.