These cables combine end cap, mode stripper, and water cooling to enable low loss transmission of high laser power levels for extended periods with stability and reliability. There are numerous configuration and connector options. Get reliable, low loss cables for delivering multi-kW laser beams over long distances — they're rugged enough to perform consistently, even in harsh environments. This milestone opens up promising applications in distributed quantum. Here we implement the coherence-based twin-field QKD protocol over a 254-kilometre commercial telecom network spanning between Frankfurt and Kehl, Germany, achieving encryption key distribution at 110 bits per second. Our results are enabled by a scalable approach to optical coherence distribution. Quantum technologies, which leverage the principles of quantum mechanics, have been found to outperform their classical counterparts on specific tasks. Among other things, past studies have highlighted the potential of quantum systems that can enable long-distance communication, using photons. Northwestern University engineers are the first to successfully demonstrate quantum teleportation over a fiberoptic cable already carrying internet traffic. The discovery introduces the new possibility of combining quantum communication with existing internet cables—greatly simplifying the. Enabling the future of quantum communication with high-performance fiber optic interconnects, DIAMOND delivers the reliability, low insertion loss, and stability required for cutting-edge quantum data exchange systems.