Complexity-Optimised Quantum Receiver with Free Beam Interface

(Funded by the German Federal Ministry of Education and Research)

Network Coordinator: Pixel Photonics GmbH

Duration: January 2022 - December 2024


Universität Heidelberg

- attocube Systems AG

- Fraunhofer HHI

- Fraunhofer IOF

- Swabian Instruments GmbH


With the rapidly advancing development of quantum computers, established and widely used cryptographic methods will no longer be secure enough in the future, so that new approaches are needed to guarantee data security in the long term. One solution is to exchange keys using light quanta - a process that promises inherent security against eavesdropping based on quantum physical principles. Current implementations of the necessary receiver modules for quantum key exchange are still technically very complex. As a result, they are complex to operate and cost-intensive - especially when commercially available detector systems are used. All of these factors together hinder the economic utilisation of such systems and thus the large-scale development of a quantum-safe communication infrastructure.

Aims and Approach

The aim of the joint project "Complexity-optimised quantum receiver with free-beam interface" (RECONNAITRE) is to develop a highly efficient, low-maintenance and easy-to-use receiver module for key exchange using light quanta. Complexity is being reduced at both component and system level. One of the focal points of the project is to research a fully integrated multi-detector system based on a novel material and design approach. In addition to developing the electronics and software required for operation, the project is also researching a highly efficient broadband interface that couples light quanta from the transmission path into the detector system. This enables high key rates to be achieved. The practical suitability and improved performance of the receiver module for quantum key exchange will be demonstrated both on a fibre optic link and in a free beam connection.

Innovations and Prospects

The project is developing a lean, robust and powerful receiver module for quantum-based key exchange that goes far beyond the current state of the art. The knowledge gained represents an important innovation for the QuNET initiative and will pave the way for the practical use of this technology beyond laboratories. In the future, it will be possible to initiate the nationwide development of a tap-proof quantum communication network, which will be essential for authorities, operators of critical infrastructure and other high-security areas in the future. The work thus makes an important contribution to achieving the overall objectives of the QuNET initiative.