  Hubbard ladders are an important stepping stone to the physics of the
two-dimensional Hubbard model. While many of their properties are accessible to
numerical and analytical techniques, the question of whether weakly hole-doped
Hubbard ladders are dominated by superconducting or charge-density-wave
correlations has so far eluded a definitive answer. In particular, previous
numerical simulations of Hubbard ladders have seen a much faster decay of
superconducting correlations than expected based on analytical arguments. We
revisit this question using a state-of-the-art implementation of the density
matrix renormalization group algorithm that allows us to simulate larger system
sizes with higher accuracy than before. Performing careful extrapolations of
the results, we obtain improved estimates for the Luttinger liquid parameter
and the correlation functions at long distances. Our results confirm that, as
suggested by analytical considerations, superconducting correlations become
dominant in the limit of very small doping.
