Entanglement and Wavelength Division Multiplexing for Quantum Cryptography Networks
Gilles Brassard · AIP conference proceedings · 2004
We describe how optical wavelength division multiplexing (WDM) can be used to build a fibre‐based network allowing many users to communicate in a secure fashion using quantum key distribution (QKD). In the simplest implementation, a certain number of trusted relays are necessary when the network gets large. However, we also show that, by using entangled QKD, trusted relays are not necessary for metro‐distance networks, and their required number is cut in half for global networks. We also report on a successful demonstration of the proposed architecture over a fibre link of 10 km with the plug&play configuration, which uses weak pulses of light and a Faraday mirror to compensate for the errors introduced by the fibre. The average interference visibility per user is 99.6 ± 0.2% (27 ± 2 dB). This guarantees the feasibility of the proposed WDM architecture.