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Quantum hacking: Experimental demonstration of time-shift attack against practical quantum-key-distribution systems

2008; American Physical Society; Volume: 78; Issue: 4 Linguagem: Inglês

10.1103/physreva.78.042333

1538-4446

Yi Zhao, Chi‐Hang Fred Fung, Bing Qi, Christine Chen, Hoi‐Kwong Lo,

Quantum Computing Algorithms and Architecture

Quantum-key-distribution (QKD) systems can send quantum signals over more than $100\phantom{\rule{0.3em}{0ex}}\mathrm{km}$ standard optical fiber and are widely believed to be secure. Here, we show experimentally a technologically feasible attack---namely, the time-shift attack---against a commercial QKD system. Our result shows that, contrary to popular belief, an eavesdropper, Eve, has a non-negligible probability $(\ensuremath{\sim}4%)$ to break the security of the system. Eve's success is due to the well-known detection efficiency loophole in the experimental testing of Bell's inequalities. Therefore, the detection efficiency loophole plays a key role not only in fundamental physics, but also in technological applications such as QKD systems.