Single Electron Transport in Ropes of Carbon Nanotube
  We have measured the electrical properties of individual bundles, or "ropes" of single-walled carbon nanotubes. Below ~10 K, the low bias conductance is suppressed for voltages below a few millivolts. In addition, dramatic peaks are observed in the conductance as a function of a gate voltage that modulates the number of electrons in the rope. We interpret these results in terms of single electron charging and resonant tunneling through the quantized energy levels of the nanotubes comprising the rope. 
Marc Bockrath, David H. Cobden, Paul L. McEuen, Nasreen G. Chopra, A.   Zettl, Andreas Thess, and R. E. Smalley