Lasers have been used to throw and catch extremely cold, single atoms. The technique could be used to assemble quantum computers in the future.
To arrange atoms that are almost as cold as absolute zero into different configurations, researchers typically grab and carry them using very focused laser beams called optical tweezers. at the Korea Advanced Institute of Science and Technology in South Korea and his colleagues wanted to find a way to minimise the amount of time the optical tweezers are in contact with the atoms, as the lasers can disturb some of the atoms鈥� properties.
They started with a small metal-and-glass box filled with rubidium atoms that were 40 millionths of a degree above absolute zero. Such ultracold atoms are very sensitive to the electromagnetic forces that light exerts on them. The team used this property to give an atom an optical kick, effectively tuning the laser to make the atom accelerate towards its destination.
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Then, a different pair of optical tweezers was turned on to catch and slow the atom down, until it stopped in the desired place, up to 12.6 micrometres away.
Ahn says that this method could make it easier to build bigger 鈥� and therefore more powerful 鈥� quantum computers from ultracold atoms. In these computers, each ultracold atom stores information, and they are all arranged into tight grids so they can process that information by interacting with neighbouring atoms through electromagnetic forces. Throwing atoms into place could also be a way to quickly reconfigure the grid if an error occurs and an atom needs to be replaced or moved, he says.
鈥淪uppose you have to add an atom into the middle of an array,鈥� says at the University of Wisconsin-Madison. 鈥淯sually, you鈥檇 have to move an optical tweezer through many points in the array, which can disturb the atoms that are there. If you can just throw the atom to the centre, you solve that problem.鈥�
Some atoms in the experiment got dropped or weren鈥檛 caught successfully, so the new method still needs some improvement, says Saffman.
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