Data security on the internet is under threat: in the future, quantum computers could decode even encrypted files sent over the internet in no time. Researchers worldwide are, therefore, experimenting with quantum networks that will enable a paradigm shift in the future when globally connected to form the quantum internet.

Such systems would be able to guarantee tap-proof communication through quantum mechanical phenomena such as superposition and entanglement, as well as cryptographic quantum protocols. However, the quantum internet is still in its infancy: high costs coupled with high energy consumption and a high level of complexity for the necessary technologies have prevented quantum networks from scaling easily.

Two researchers at the Institute of Photonics at the Leibniz University Hannover want to remedy this situation. Using frequency-bin coding, they have developed a novel method for entanglement-based quantum key distribution. This quantum mechanical encryption technique uses different light frequencies, i.e. colors, to encode the respective quantum states. The method increases security and resource efficiency.