EVIDENCE FOR A SUPERFLUID DENSITY IN T-J LADDERS

Applying three independent techniques, we give numerical evidence for a finite superfluid density in isotropic hole-doped t-J ladders. We show the existence of anomalous flux quantization, emphasizing the contrasting behavior to that found in the ''Luttinger liquid'' regime stabilized at low electron densities. We consider the nature of the low-lying excitation modes, finding the 1D analog of the superconducting state; using a density matrix renormalization group approach, we find long range pairing correlations and exponentially decaying spin-spin correlations.