A Chinese team has demonstrated a city-scale device-independent quantum key distribution (DI-QKD) technique that closes hardware vulnerabilities in existing quantum encryption methods.[1] This method uses quantum entangled particles for theoretically unbreakable encryption of keys, thereby eliminating the risk of hackers through backdoors in the hardware.[1] Scientists trapped a rubidium atom at each end of an optical fiber, stabilized it with lasers, and induced the emission of single photons, which bound the separated atoms together.[1] They transferred the photons into a telecommunications wave for greater reach through fiber.[1] After 26 days of data collection, they successfully generated and shared a key over a distance of 11 kilometers.[1] In theory, with 23 years of data collection, they could transmit the key over 100 kilometers.[1] This progress confirms the principle of operation of DI-QKD and opens the way to a secure quantum internet.[1]