Wolfgang Ertmer, Gerhard Birkl and their colleagues plan to use rubidium atoms as their storage devices.

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But holding enough lone rubidium atoms in place to have a chance of making a working computer is tricky.

ECONOMIST: Quantum computers

They used a beam of photons to measure the small magnetic field produced by a gas made up of a million ultra-cold rubidium atoms.

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This conical beam is then reflected into a cluster of 1m or so rubidium atoms, which are held trapped in a magnetic field within a vacuum chamber.

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Using this technique, and a sufficient number of microlenses, the team created an array of 80 dipole traps, each of which captured about 100 rubidium atoms, spaced 125 microns from one another.

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One effect of the beam is to polarise the cloud of electrons surrounding each rubidium nucleus, meaning that part of the atom becomes a negatively charged pole, and part a positively charged pole.

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As the researchers report in a forthcoming issue of Physical Review Letters, they managed to hold significant numbers of isolated rubidium atoms in place by shining a laser beam on to an array of microscopic lenses.

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Actually creating such condensates fell to Eric Cornell and Carl Wieman, of the University of Colorado, Boulder, who made one out of rubidium atoms, and Wolfgang Ketterle, of the Massachusetts Institute of Technology, who did the same with sodium.

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Since they were first made in 1995, Bose-Einstein condensates have become commonplace as experimental tools. (They are particularly valued for their ability to slow the speed of light all the way down to zero.) Dr Steinhauer and his colleagues created a condensate out of a gas of rubidium atoms held in a magnetic trap.

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