Higher-security thresholds for quantum key distribution by improved analysis of dark counts

We discuss the potential of quantum key distribution (QKD) for long-distance communication by proposing an analysis of the errors caused by dark counts. We give sufficient conditions for a considerable improvement of the key generation rates and the security thresholds of well-known QKD protocols such as the Bennett-Brassard 1984, Phoenix-Barnett-Chefles 2000, and six-state protocols. This analysis is applicable to other QKD protocols like the Bennett 1992 protocol. We examine two scenarios: a sender using a perfect single-photon source and a sender using a Poissonian source.