A research team from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), led by Prof. Jianwei Pan, Qiang Zhang, and Kai Chen, in collaboration with CHEN Jingling from Nankai University, has achieved the loophole-free test of Hardy’s paradox for the first time. The team successfully demonstrated Hardy’s nonlocality, closing both the detection efficiency loophole and the locality loophole. Their findings were published in Physical Review Letters as an Editor’s Suggestion.
Hardy’s paradox, introduced by Lucien Hardy in the 1990s, offers a simplified test of local realism—the classical idea that physical properties exist independently of observation and that no signals exceed the speed of light. This paradox exposes the conflict between quantum mechanics and local realism by demonstrating that, under certain conditions where three “Hardy events” have a zero probability, quantum mechanics predicts a non-zero probability for a fourth event, which contradicts local realism.
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