Mikio Fujiwara

We show joint propagation of CV-QKD with successful secret key generation over 24 hours with 100 state-of-the-art EDFA amplified coherent WDM channels amounting to a total classical bitrate of 18.3~Tbit/s.

The key relay protocol (KRP) plays an important role in improving the performance and the security of quantum key distribution (QKD) networks. On the other hand, there is also an existing research field called secure network coding (SNC), which has similar goal and structure. We here analyze differences and similarities between the KRP and SNC rigorously. We found, rather surprisingly, that there is a definite gap in security between the KRP and SNC; that is, certain KRPs achieve better security than any SNC schemes on the same graph. We also found that this gap can be closed if we generalize the notion of SNC by adding free public channels; that is, KRPs are equivalent to SNC schemes augmented with free public channels.

To construct a large-scale quantum key distribution network (QKDN) as future secure infrastructure, it is necessary interwork many QKDNs. Here, we demonstrate an interoperable key relay between two different types of QKDNs: a centralized QKDN and a distributed QKDN. In the demonstration, we build an experimental environment for interworking by using physical QKDNs and implement three fundamental functions (key relay, delivery confirmation, and status information collection) for performing key relay between heterogeneous QKDNs.

We developed a genome sequence data storage system using a distributed storage system on a quantum key distribution (QKD) network and have successfully demonstrated secure storage and data reconstruction for genome sequence data. The proposed system thus has potential for use as a distributed storage system in genome analysis.