Scientists from the University of Bonn have constructed the world's smallest pair of tweezers which are capable of moving atoms around one by one and might hold the key to superfast "quantum computers" of the future. In this week's Nature, Arno Rauschenbeutel and his colleagues describe how they have used two intersecting laser beams to position individual atoms from a cloud of cooled caesium. The lasers are set up so that they each generate a standing wave - literally a series of peaks and troughs - and the result is that the caesium atoms arrange themselves at the crests, which are about one two-thousandth of a millimetre apart. Then, by pulsing the laser so that the peaks and troughs move along the beam, the atoms can be carried forwards and backwards. The second laser beam, which points upwards, can then use the same trick to move the atoms up and down. In this way it's possible to achieve highly-precise positioning of individual atoms in three-dimensional space, and then read their position using a laser tuned to the right frequency. This atomic abacus could in turn be used to rapidly store and retrieve quantum information, which will be necessary to build more powerful microprocessors in the future.


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