Encrypting data in a way that ensures secure communication is an ever-growing challenge because crucial components of today's encryption systems cannot withstand future quantum computers. Researchers around the world are therefore working on technologies for novel encryption methods that are also based on quantum effects. The phenomenon of so-called quantum entanglement plays a particularly important role here. This means that in a quantum network, the stationary qubits of the network are entangled with the communication channel, which usually consists of photons (light particles). For the first time, physicists at the University of Bonn have now been able to demonstrate quantum entanglement between a stationary qubit, i.e. a two-state quantum system, and a photon with direct coupling to an optical fiber. The study has been published in the journal npj Quantum Information.