Anomalous conductance quantization in carbon nanotubes.

Conductance measurements of carbon nanotubes containing gated local depletion regions exhibit plateaus as a function of gate voltage, spaced by approximately 1e(2)/h, the quantum of conductance for a single (nondegenerate) mode. Plateau structure is investigated as a function of bias voltage, temperature, and magnetic field. We speculate on the origin of this surprising quantization, which appears to lack band and spin degeneracy.