Vienna, Austria - Researchers from across Europe have built the largest quantum key distribution network ever, sending secure, quantum-encrypted information over an eight-node, mesh network.
With an average link length of 20 to 30km, and the longest link being 83 kilometres, the network breaks all records. The researchers write, "In our paper we have put forward, for the first time, a systematic design that allows unrestricted scalability and interoperability of QKD technologies."
The quantum key distribution (QKD) network is based on the internal glass fibre ring of Siemens and four of its dependencies across Vienna plus a repeater station, near St Pölten in Lower Austria. The demonstration involved secure telephone communication and video-conference as well as a rerouting experiment which demonstrated the functionality of the SEcure COmmunication network based on Quantum Cryptography (SECOQC).
Quantum cryptography uses the quantum mechanical behaviour of photons to enable highly secure transmission of data beyond that achievable by classical methods.
The photons themselves are used to distribute cryptographic keys to access encrypted information which can be sent along fibre optic cables. Quantum indeterminacy - which states that measuring an unknown quantum state will change it - means that the information can't be accessed by a third party without corrupting it beyond recovery.
The network was created by researchers from organisations including the AIT Austrian Institute of Technology (formerly Austrian Research Centers), id Quantique, Toshiba Research in the UK, Université de Genève, the University of Vienna, CNRS, Thales, LMU Munich and Siemens.
The SECOQC Key Distribution Network in Vienna is published in the New Journal of Physics' Focus Issue on 'Quantum Cryptography: Theory and Practice.