  Relatively low magnetic fields applied parallel to the axis of a chiral
single-walled carbon nanotube are found causing large modulations to the
p-channel or valence band conductance of the nanotube in the Fabry-Perot
interference regime. Beating in the Aharonov-Bohm type of interference between
two field-induced non-degenerate sub-bands of spiraling electrons is
responsible for the observed modulation with a pseudo period much smaller than
that needed to reach the flux quantum F0 = h/e through the nanotube
cross-section. We show that single-walled nanotubes represent the smallest
cylinders exhibiting the Aharonov-Bohm effect with rich interference and
beating phenomena arising from well-defined molecular orbitals reflective of
the nanotube chirality.
