Marco Gramegna

Twin-Field Quantum Key Distribution (TF-QKD) is an innovative family of protocols characterized by a weaker dependence of the achievable secret key rate on the channel loss, with respect to conventional QKD solutions. In this work, we discuss several important aspects encountered in TF-QKD when transitioning from point-to-point links to a network configuration. 1) The effects of path length mismatch between the two arms of the link (A-C and B-C) is discussed in several configurations. 2) The noise contributions (stronger in in-field deployment) are meticulously analyzed, their effect on the final key rate is estimated and solutions to mitigate the problem are implemented. 3) The topic of building complex and large networks with TF-QKD is tackled to find advantageous configurations. Interconnected macro-star networks based on TF-QKD are simulated by means of the “qkdnetsim” package of the network simulator “ns3”. The upcoming deployment of national QKD networks requires dedicated studies in this direction to build efficient and long-range solutions, compatible with current telecom standards.

The second quantum revolution is underway and the deployment of Quantum Technologies (QT) keeps pace with it. This technological paradigm-switch creates opportunities and challenges for industry, innovation and society. Several large companies, as well as start-ups, have started to develop and engineer quantum devices or begun to integrate them into their products: the commercial success of QT, together with progress in research and development, relies on certification and reliability built upon internationally agreed standards and metrological traceability. In this scenario, a group of European National Metrology Institutes (NMIs) and Delegated Institutes (DIs) have recently created a European Metrology Network for Quantum Technologies (EMN-Q) under the auspices of EURAMET, the European association of NMIs and the regional metrology organisation (RMO) of Europe. In this talk, a short overview of the EMN-Q organization will be provided, together with a report about the current status of the Strategic Research Agenda and on the Technological Roadmaps. Afterwards, the discussion will be focused on QKD and how the EMN-Q has started to answer to the metrology needs of the QKD community.