Cisco, Qunnect, NYU, and QTD Systems have demonstrated a quantum entanglement network across 17.6 km of live telecom fiber in New York City, connecting three nodes between Brooklyn and Manhattan. The experiment achieved entanglement swapping rates of over 5,400 pairs per hour deployed and 1.7 million pairs per hour locally, with polarization fidelity above 99%. A key breakthrough was eliminating the shared laser synchronization requirement that previously limited scalability, replacing it with Cisco's software-defined control plane using the White Rabbit timing protocol for picosecond-level accuracy. The hub-and-spoke architecture uses cryogenic equipment at central hubs and room-temperature hardware at edges, enabling expansion on existing fiber infrastructure without rebuilding core synchronization systems.
