Quantum Network for secure Communication

The researchers want to use a new fiber optic test track at the Karlsruhe Institute of Technology (KIT ) to transmit, test and further develop such quantum keys. They also want to set up a quantum network that will enable quantum computers to be linked, among other things. With the fiber optic test track, the researchers are using state-of-the-art technologies such as highly coherent lasers to generate and transmit the quantum keys. These are crucial for tap-proof communication, as they are based on physical laws and not on mathematical assumptions like previous keys, which can be broken with future quantum computers.

The fiber optic test track is an important platform for quantum research and connects Campus South and Campus North at KIT. © KIT

With a length of 20 km, the test track connects specially equipped laboratories with elaborate lasers and cryostats at KIT's South Campus and North Campus as a quantum optical transmission line. The light-conducting core of the fiber optic cable has a diameter of only around 9 µm - for comparison: a human hair is around 60 µm thick.

Important platform for quantum research

"The topic of quantum communication is of great strategic importance for KIT. I am all the more pleased that KIT is providing researchers with an important infrastructure to explore the possibilities of quantum physics with the test track that has been built," says Professor Oliver Kraft, Vice President Research at KIT. "We are thus making a decisive contribution to advancing research and development in the field of quantum network technologies and bringing them to applications."

"With the fibre-optic test track, we now have a platform to further develop quantum key distribution, carry out fundamental characterizations and integrate it into conventional communication," explains project leader Professor David Hunger from the KIT Institute of Physics. Building on this, the scientists are developing new transmission protocols for the keys. "We want to use new methods to make quantum cryptography more efficient and practicable. Here, for example, we are working together with KEEQuant, a start-up company in the field of quantum-safe communication," explains Hunger. "With the help of special materials, we want to generate high-purity quantum light - i.e. individual light particles - and thus increase transmission rates."

Building a quantum network

In addition, the researchers are building a quantum network in several steps in order to research the future quantum internet. They are focusing on two key steps: firstly, the storage of quantum information in special quantum memories and secondly, the quantum mechanical entanglement of the memories. This makes it possible to realize quantum repeaters that can transmit quantum information over long distances. Since entanglement is a basic element of quantum computers, they can be connected to each other in a quantum internet by optical transmission of the entanglement.

Part of the Chem4Quant Cluster of Excellence initiative

The project is a central infrastructure of the Cluster of Excellence initiative 'Chem4Quant', in which researchers from KIT, the University of Ulm and the University of Stuttgart are specifically developing material structures for future quantum technologies and focusing on a new sub-area of quantum technologies, molecular quantum systems. The project is also an important component for research into quantum repeaters within the joint project Quantumrepeater.Net (QR.N) of the Federal Ministry of Education and Research and a contribution to the QuantumBW innovation campus.