Cavendish Research Paper selected as one of "100 Top Science Stories of 2007" by Discover Magazine

"Gigahertz quantised charge pumping", a paper by Cavendish researchers in the Semiconductor Physics Group in the Cavendish Laboratory in collaboration with researchers at the National Physical Laboratory and published in Nature Physics 3, 343 - 347 (2007), was recently selected by Discover Magazine as one of "100 Top Science Stories of 2007".

Electron pumps, which feature in the paper, have been studied since the early 1990s. These pumps cause an electric current to flow by moving electrons one at a time. If an electron pump could be operated with sufficient speed and accuracy, it would lead to profound changes in the way electric current is defined in the International System of Units (SI). Applications from quantum based computing to quantum cryptography could also make use of this fast and accurate electron pump. For any single-electron transport device such as these electron pumps to be of a practical use in the metrological (Science of Standards) community, two fundamental criteria must be satisfied. Firstly, the current generated by the device has to be large enough that the actually measurements of the current is possible. This is directly related to how fast the electrons are moved. Secondly the uncertainty in the generated current which is a measure of the consistency at which the single electrons are being transported, needs to be smaller than 1 part in 10-6, that is for very one million electrons pumped only one extra electron is gained or lost during the entire process.

The significance of the results published in Nature Physics (April 2007) on electron pumping lie in the speed at which this new pump is operated, and the actual operation of the device. Three billion electrons were moved each second in a controlled way, more than 100 times faster than the previous pump record.