  Recent experimental and theoretical results on intrinsic superconductivity in
ropes of single-wall carbon nanotubes are reviewed and compared. We find strong
experimental evidence for superconductivity when the distance between the
normal electrodes is large enough. This indicates the presence of attractive
phonon-mediated interactions in carbon nanotubes, which can even overcome the
repulsive Coulomb interactions. The effective low-energy theory of rope
superconductivity explains the experimental results on the
temperature-dependent resistance below the transition temperature in terms of
quantum phase slips. Quantitative agreement with only one fit parameter can be
obtained. Nanotube ropes thus represent superconductors in an extreme 1D limit
never explored before.
