Continuous-Variable Multi-User Quantum Key Distribution for 5G and distributed storage applications

Quantum key distribution is a quantum technology providing cryptographic keys with future proof and therefore quantum-safe security. As a two-party protocol, quantum key distribution is usually used with direct point-to-point fiber connections. However, typical telecom infrastructures consist also of point-to-multipoint passive optical networks in the access domain which use a beam splitter to cost-efficiently connect multiple users to a central access node.

In the CVSTAR project, we aim to develop multi-user quantum key distribution protocols, to implement prototypes and to demonstrate two cost-efficient use-cases in existing telecom infrastructure: encrypting fronthaul traffic of current 5G and future 6G mobile networks and information theoretical secure and redundant distributed data storage.

Our quantum key distribution solutions are based on continuous-variable quantum technology making use of amplitude and phase quadratures of light and coherent detection similar to high-speed coherent optical telecommunication. In the multi-user scenario, we consider different levels of trust, with users either not trusting each other or collaborating with each other, which will allow service providers to optimally map infrastructure and use-cases. While our field demonstrations will be based on coherent states exclusively, lab demonstrations will also employ squeezed light which enables generation of cryptographic keys between remote receivers.

We expect that the methods developed in CVSTAR will constitute first steps towards a future deployment of quantum key distribution in access networks. The applications to be demonstrated will be door openers to other future multi-user scenarios like distributed computing. Finally, it may enable quantum-safe cryptography for end-users over fiber-to-the-home.





  • Coordinator: Tobias Gehring (Technical University of Denmark, DK)
  • Jeppe Christiansen (TDC NET, DK)
  • Andreas Poppe (AIT Austrian Institute of Technology, AT)
  • Christoph Pacher (fragmentiX Storage Solutions GmbH, AT)
  • Vladyslav Usenko (Palacky University Olomouc, CZ)

Call topic

Applied Quantum Science

Start date

June 2022


36 months

Funding support

€ 1 104 474