Light drives electron logic

Although quantum computers have the potential to solve very large problems very quickly, and full-size quantum computers would render most of today's security software obsolete, building a quantum computer is extremely difficult, and working models are at least one to two decades away.

Researchers from the University of Michigan at Ann Arbor and the University of California San Diego at La Jolla have taken the proposition a step forward by demonstrating a conditional logic gate made from a pair of electrons trapped in a quantum dot.

The researchers' device acts as a two-bit conditional logic gate, and is controlled using light. It is the first such gate implemented in a solid-state device, according to the researchers.

A working quantum computer would require thousands or millions of such gates. The researchers are currently refining a method that includes a third electron, which will allow the system to hold information longer and be scaled up to large numbers of gates.

It will take at least ten years to assess the potential of different types of quantum computers, and longer than that to build one, according to the researchers. The work appeared in the August 7, 2003 issue of Science.