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 e2/h, the quantum of conductance for a single (non-degenerate) 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. 
M. J. Biercuk, N. Mason, J. Martin, A. Yacoby, C. M. Marcus