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Communications of the ACM


Quantum Technology Forgoes Unconditional Security to Extend its Reach

quantum communication ground station, composite photo

This composite photo taken on Dec. 10, 2016 shows a quantum communication ground station in southwest China's Tibet Autonomous Region.

Credit: Getty Images

The summer of 2017 saw two Chinese projects demonstrate the potential to move encryption based on quantum techniques from small-scale trials into networks that can span the globe.

The completion of an $85-million fiber-optic network that runs 1,200 miles from Beijing to Shanghai through Jinan and Hefei marks a distance record for quantum key distribution (QKD). Designed to overcome a fundamental problem in conventional cryptography—how to transmit a private encryption key securely to another user without risk of it being intercepted—QKD has until recently been limited to networks that span no more than a few hundred miles.


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