Superconductivity in the three-leg Hubbard ladder: a Quantum Monte Carlo   study
  Quantum Monte Carlo method is used to look into the superconductivity in the three-leg Hubbard ladder. The enhanced correlation for the pairing across the central and edge chains, which has been predicted in the weak-coupling renormalization as an effect of coexistence of gapful and gapless spin modes, is here shown to persist for intermediate interaction strengths. 
Takashi Kimura, Kazuhiko Kuroki, Hideo Aoki