Orion, for example, operates near absolute zero, and previous attempts to build single-photon detectors have suffered similar constraints.
拿Orion来说，要在接近绝对零度下运行，而之前尝试建造单个光子检测器的努力同样受到类似的局限。
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The atoms had an effect called electromagnetically induced transparency (EIT), which enabled the scientists to separate the single-photon precursors from the main wave packet.
But this study is the first to experimentally show that optical precursors exist at the single-photon level, and that they are the fastest part of the single-photon wave packet.