Phys.org  May 25, 2022 Researchers in Germany have created a scalable star-shaped quantum-key-distribution (QKD) optical-fiber network using WDM of broadband photon pairs to establish key exchange between multiple pairs of participants. They demonstrated simultaneous bipartite key exchange between any possible combination of participants and showed that the quantum bit error rate (QBER) itself can be used to stabilize the phase in the interferometers by small temperature adjustments. The key distribution is insensitive to polarization fluctuations in the network, enabling key distribution using deployed fibers even under challenging environmental conditions. They demonstrated that the network could be extended to 34 participants […]