In a QD, electrons are restricted to a region of space so tiny as to enforce a quantum regime; the electrons may only have certain discrete energies, which can be useful, depending on the circumstances, in producing laser light or in detectors and maybe even future computers. QDs are usually fabricated in a semiconductor and controlled with voltages applied to nearby electrodes. In recent years, though, fast-moving QDs have been fashioned by trapping electrons in the minima of surface acoustic waves that zip through a channel past static surface gates. (For more on SAWs, see Physics Today, March 2002, page 42 .) A team of physicists at the Cavendish Laboratory at the University of Cambridge has now determined the tunneling rate of electrons from such dynamic QDs, a necessary step for putting the traveling dots to practical use. The experimenters calculated the tunneling rates for the case of 1,...

You do not currently have access to this content.