Trapping Single Atoms For Quantum Computing

By making tiny holes that contain nothing at all, scientists at Ohio State University (OSU) have taken a step toward the development of powerful new computers. The holes – dark spots in an egg carton-shaped surface of laser light – could one day cradle atoms for quantum computing.

Quantum computers could enable much faster computing than is possible today. One strategy for making quantum computers involves packaging individual atoms on a chip so that laser beams can read quantum data.

The OSU scientists recently designed a chip with a top surface of laser light that functions as an array of tiny traps, each of which could potentially hold a single atom. The design could enable quantum data to be read the same way CDs are read today.

Other research teams have created similar arrays, called optical lattices, but those designs present problems that could make them hard to use in practice. Other lattices lock atoms into a multi-layered cube floating in free space. But manipulating atoms in the center of the cube would be difficult.

The OSU lattice features a single layer of atoms grounded just above a glass chip. Each atom could be manipulated directly with a single laser beam.

The lattice forms where two sets of laser beams cross inside a thin transparent coating on the chip. The beams interfere with each other to create a grid of peaks and valleys – the egg carton-shaped pattern of light.

The physicists expected to see that much when they first modeled their lattice design on a computer. However, the simulations showed that each valley contained a dark spot, a tiny empty sphere surrounded by electric fields that seemed ideally suited for trapping single atoms and holding them in place.

The scientists were able to create an optical lattice of light, though the traps are too tiny to see with the naked eye. The next step is to see if the traps actually work as the model predicts.

So far, they've been able to form about a billion gaseous rubidium atoms into a pea-sized cloud with magnetic fields. Now they are working to move that cloud into position above a chip supporting the optical lattice. Theoretically, if they release the atoms above the chip in just the right way, the atoms will fall into the traps.




Fig 1: In the first part of the experiment, lasers and magnetic fields capture vaporized rubidium atoms and form them into a pea-sized cloud.



Fig 2: The device holding the cloud then slides down a track to move the atoms into position above a glass chip.



Fig 3: Then the magnetic fields are then shut off, releasing the atoms, which fall onto a surface of laser light.

Visit http://researchnews.osu.edu/archive/eggcarton.htm