Slovenian Quantum Coomunication Infrastructure Demonstration

SiQUID will implement quantum key distribution (QKD) links between multiple government nodes in Slovenia and a test-bed quantum network between research institutions in Ljubljana for advanced quantum-communication protocols. We will coordinate our efforts with public and industrial stakeholders, and we will train key personnel, young researchers and engineers in quantum technology. The first test nodes implemented will be based on our recent first demonstration of QKD links between three European countries (arXiv:2203.11359-paper attached). We will harness directly modulated laser diodes to ensure the phase randomisation between adjacent pulse sequences, and we will use a high-assurance random number generator to randomise the choice of the state preparation basis. These improvements promise a higher level of security, a larger range, and a higher key rate. This will form the basis for the implementation of the QKD links between government nodes. To reduce the cost of future QKD networks, SiQUID will investigate the feasibility of cheaper alternatives for the detection nodes by balancing cost against the key rates achievable in metropolitan links. At the same time, we will use superconducting nanowire single-photon detectors (SNSPDs) to implement high efficiency links. We will use these to test long-distance links between distant cities in Slovenia, and to nodes close to neighbouring countries. Moreover, we will test advanced quantum communication protocols like measurement-device-independent (MDI) QKD and the long-distance distribution of entanglement to further increase the security of QKD implementations, and to prepare the ground for a future full-fledged quantum communication network. We are in close contact with QCI initiatives in neighbouring countries to facilitate the harmonisation of the national efforts, and to facilitate future cross-border links and the implementation of the space segment of EuroQCI.