Quantum encryption method demonstrated at city-sized distances for the first time

Researchers have successfully demonstrated quantum key distribution (QKD) over city-scale distances for the first time, addressing growing fears that quantum computers could soon break conventional encryption methods. The breakthrough proves QKD—a system where eavesdropping attempts disrupt quantum states, exposing intrusions—can function across urban networks, a critical step toward real-world deployment. Experiments conducted in February 2026 validated the method’s feasibility in practical, large-scale environments, overcoming prior limitations tied to signal degradation over long distances. This advancement directly counters the threat posed by quantum computing’s ability to crack RSA and ECC encryption, which secure everything from banking to government communications today. The achievement marks a pivotal shift toward quantum-safe infrastructure, offering a provably secure alternative as classical cryptographic systems face obsolescence.