- 11 November 2004 -

GaAs and quantum entanglement

Physicist Alfred Forchel at the University of Würzburg, Germany, led been team leader in the creation of a 'laboratory' inside a microscopic pillar made from stacked layers of gallium arsenide and aluminium arsenide.

Another physicist Galina Khitrova, at the University of Arizona, Tucson, has built a gallium arsenide crystal atom by atom, leaving room for the quantum dots to be added as the crystal grew.

The tiny cavity inside a crystal makes an ideal laboratory for quantum experiments, according to two teams who have entangled light and matter inside a solid for the first time and should assist in the study of quantum entanglement.

Both teams used holes inside the GaAs to house a quantum dot. A laser pulse directed at the QD jolts it into emitting a particle of light, which is entangled with both the quantum dot and the electric field of the cavity itself.

Trapping the entangled objects inside semiconductors means the teams can connect them to conventional circuits. "The photonic crystal slab offers the attractive possibility of interconnecting various sources and detectors all on the same chip," says Khitrova. Both groups publish their research in Nature.

Physicists have suggested that quantum work should be focused on devices that could be integrated with conventional silicon electronics. These new semiconductor cavities appear to meet this requirement.