Evidence for a superfluid density in t--J ladders

TL;DR

This paper provides numerical evidence for superfluid density in t--J ladders, demonstrating anomalous flux quantization, superconducting-like excitations, and long-range pairing correlations, contrasting with Luttinger liquid behavior at low densities.

Contribution

It introduces three independent numerical techniques to establish superfluid density and superconducting features in t--J ladders, a novel insight into their quantum state.

Findings

Finite superfluid density in t--J ladders

Anomalous flux quantization observed

Long-range pairing correlations detected

Abstract

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, emphasising the contrasting behaviour to that found in the `Luttinger liquid' regime stabilised at low electron densities; We consider the nature of the low-lying excitation modes, finding the 1-D analog of the superconducting state; And using a density matrix renormalization group approach, we find long range pairing correlations and exponentially decaying spin-spin correlations.