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June 18, 2007

Atom trap used to spot individual atoms

A device that can hold hundreds of atoms in a 3D array, and image each one individually, has been developed by scientists in the US.

The team [David Weiss, Karl Nelson, and Xiao Li at the Pennsylvania State University] used three lasers arranged at right angles to create a 3D lattice in which they trapped 250 atoms of cesium.

The researchers then photographed the atoms in the array, layer by layer, proving that they could see each one. "If you can't see them, it's much harder to manipulate them individually," David Weiss says. But, he adds, because they can make out individual atoms, "it's pretty clear that we should be able to manipulate them independently of each other".

The team now plans to address individual atoms with a highly focused laser beam, which will change their energy state and make nearby atoms interact, Weiss says. This should make the atoms enter the quantum physical state known as "entanglement" that is essential for doing quantum computations.

"Now that there's this huge array, you can start seriously thinking about scaling up" the approach of using neutral atoms as qubits for quantum computing, says Trey Porto of the National Institute of Standards and Technology in Gaithersburg, Maryland. "It's certainly relevant to quantum computing because you're going to need lots of qubits.”

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