Nanotubes are ideal systems for studying the transport of electrons in one dimension, and have commercial potential as nanoscale wires, transistors and sensors. For many years, studies of quasi-one-dimensional systems, such as conducting polymers, have provided a fascinating insight into the nature of electronic instabilities in one dimension. In addition, 1-D devices such as "electron waveguides" - in which electrons propagate through a narrow channel of material - have been created. Experiments on these devices have shown, for example, that the conductance of "ballistic" 1-D systems - in which electrons travel the length of the channel without being scattered - is quantized in units of the charge on the electron squared divided by the Planck constant.
These systems, however, have been limited by the fact that they are inherently complex and/or difficult to make. What has been lacking is the perfect model system for exploring one-dimensional transport - a 1-D conductor that is cheap and easy to make, can be individually manipulated and measured, and has little structural disorder. Single-wall carbon nanotubes fit this bill remarkably well. These thin, hollow cylinders of carbon were discovered in 1993 by groups led by Sumio Ijima at the NEC Fundamental Research Laboratory in Tsukuba, Japan, and by Donald Bethune at IBM's Almaden Research Center in California - and were first mass-produced by Rick Smalley's group at Rice University in Texas. Since then, this new type of 1-D conductor has been the focus of amazingly intense study.
In the June issue of Physics World magazine, Paul McEuen from the University of California at Berkeley and the Lawrence Berkeley National Laboratory writes about the creation of tiny nanoelectronic devices in which nanotubes are the active element.