Getting individual atoms under control

A key step towards developing a quantum computer has been taken by US researchers who have devised a method of manipulating individual atoms.

Ohio State University’s physics department is building a lattice of laser beams suspended above a reflective surface to act as a trap for atoms. Other researchers have already built lattices suspended in a gas, but the Ohio team is the first to build a device that can manipulate each atom individually.

Lattices suspended in a gas fail to give physicists control over individual atoms. This is because those in the middle can only be reached by first striking the atoms on the outside of the lattice, said Ohio’s Dr Greg Lafyatis.

‘I think there’s a serious deficiency there that has not been addressed. The basic issue is that if you have an atom in a bunch, you hit the other atoms.’

The Ohio team will spend the summer attempting to place individual atoms in the holes created by the lattice of laser beams. Once this has been achieved, it will spend the next year ensuring that its method of capturing the atoms enables them to retain the properties that make quantum computing possible.

In existing computers, atoms are either one or zero. In quantum computers, individual atoms can be both one and zero at the same time.

This should enable quantum computers to be built that have far greater processing power than existing computers. The difficulty for physicists is designing systems that enable them to manipulate individual atoms while retaining the properties that make the atoms usable for quantum computing.

Interference from the surface material is a particular problem. The surface is made of silica with a tiny layer of reflective material on top. The individual atoms, which are trapped by the lattice, are separated from the surface by just 150nm.

‘The issue is whether the atoms interact strongly with the surface and screw up their properties,’ said Lafyatis.