Summary
A USTC team has set a new milestone in device-independent quantum key distribution, reporting in Science that they achieved fully secure finite-key DI-QKD over 11 km of optical fiber, and positive key rates out to 100 km in the asymptotic regime. This moves DI-QKD from lab-scale proofs to city-scale relevance, showing that security guaranteed by observed Bell violations can survive real fiber losses and noise, without having to trust the internal workings of the hardware.
The leap is striking when set against the 2022 benchmarks. Oxford extracted finite keys at only 2 m with trapped ions, Munich reached 700 m but only asymptotically, and an earlier USTC photonic test hit 220 m without full protocol features. USTC’s 11 km finite-key result is roughly a 3,000x distance gain in three and a half years, and the 100 km asymptotic signal suggests the physics holds at metropolitan and even intercity scales.
For CISOs and cyber leaders, this is not plug-and-play yet. Keys were not extracted at 100 km, and the setup relies on ultra-efficient detectors, very low-loss links, and rigorous randomness and synchronization. Still, it marks a credible path for future high-assurance links where device trust and supply chain risk are major concerns. The near-term play remains PQC for broad coverage, with DI-QKD emerging as a complementary control for the most sensitive, short-to-midrange connections as engineering catches up.
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See the original article at: https://postquantum.com/security-pqc/china-di-qkd-100/