The science-fiction fantasy of teleportation became reality this year, at least on the atomic scale. In independent papers published in June, groups led by experimental physicists Rainer Blatt of the University of Innsbruck in Austria and by David Wineland of the National Institute of Standards and Technology in Boulder, Colorado, described using laser pulses to transfer information from one atom to another in a different location. Although their methods were slightly different, the results were exactly the same: The second atom became completely indistinguishable from the first, just as if information had disappeared from one atom and appeared at the other one without traveling through the space in between.
The distances involved are slight—less than 200 micrometers—and the technique works only for information about the atoms, not the atoms themselves, making it a far cry from the images conjured up by Star Trek’s transporter. Nevertheless, quantum teleportation is a giant step toward one of physicists’ most ambitious goals: building a quantum computer—an ultrafast, supersecure, huge-memory number-crunching device that uses atomic particles instead of transistors to retain and process information.
Teleportation is possible because of the vagaries of quantum mechanics, which allow particles to share information even if they are physically separated. This phenomenon, known as entanglement, is so odd that Albert Einstein uncomfortably referred to it as “spooky action at a distance.” The two experiments affirm not only that this process happens but that it could be put to practical use.
Entanglement is crucial to a quantum computer because it will allow the device’s computational bits to shuttle information back and forth without touching. Teleportation had previously been demonstrated with particles of light, or photons, but they are too ephemeral and fragile to be useful in data storage. Blatt and Wineland plan to scale up their experiments to perform teleportation through arrays of more interconnected atoms, taking one more step toward a practical quantum computer.
