  We report the experimental observation of quantized conductance by Rashba
bands at the surface of 50-nm Bi nanowires. With increasing magnetic fields
along the wire axis, the wires exhibit a stepwise increase of conductance with
as many as four distinct plateaus together with oscillatory thermopower. The
observations can be accounted for by the increase of the number of propagating
surface modes. The modes have very high mobility and are associated with
Aharonov-Bohm interference around the perimeter consistently with theory of
quasiballistic one-dimensional nanowires considering that Lorentz forces
decouple the modes from scattering at the nanowire surface.
