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A central tenet of quantum information processing asserts that an unknown qubit cannot be cloned (see Physics Today, February 2009, page 76). But the unknown state of one qubit can be transferred to another qubit in a process termed quantum teleportation. The first experimental demonstrations succeeded in teleporting a qubit state a meter or so (see Physics Today, February 1998, page 18). Subsequent experiments with photons, whose polarizations form a convenient basis for quantum information, have used fiber optics to achieve teleportation over hundreds of meters. But practical quantum communication will require teleportation over much greater distances. Jian-Wei Pan, Cheng-Zhi Peng, and coworkers at the University of Science and Technology of China and Tsinghua University have now transferred a qubit state through free space over a distance of 16 km, from "Alice" in the Beijing suburb of Badaling, across towns and roads, to "Bob" in Huailai, on the other side of Guanting Reservoir.

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