Abstract

Quantum key distribution (QKD) [1] is a maturing technology that has evolved from an abstract idea to practical systems that are even commercially available. As with every new technology there are still plenty of new developments and the translation from theory to a practical system is difficult. In a security application, the issue of translating theoretical ideas to a working device is even more critical, because any assumption that is made in the theory needs to be verified in the actual implementation. In QKD, we have learned this the hard way, when it was realized that some devices could actually be hacked [2], not because the theory was wrong, but because a practical device is always much more complicated than even the most elaborate security proof. While keeping the security aspect under control, experimenters want to optimize their systems so that they can deliver the highest secure key rate possible under the conditions of a chosen quantum channel.

© 2009 IEEE