Superfluidity of fermions with repulsive on-site interaction in an anisotropic optical lattice near a Feshbach resonance

TL;DR

This study uses TEBD to explore a 1D Hubbard model with particle-assisted tunneling and repulsive interactions, revealing a novel phase with coexisting superfluid and charge-density-wave orders near a Feshbach resonance.

Contribution

It demonstrates that particle-assisted tunneling induces a new phase with coexisting orders, differing from conventional Hubbard models, in a 1D fermionic system.

Findings

Identification of a phase with coexisting superfluid and charge-density-wave orders

Particle-assisted tunneling leads to qualitatively new physics

Distinct from conventional positive-U Hubbard model

Abstract

We present a numerical study on ground state properties of a one-dimensional (1D) general Hubbard model (GHM) with particle-assisted tunnelling rates and repulsive on-site interaction (positive-U), which describes fermionic atoms in an anisotropic optical lattice near a wide Feshbach resonance. For our calculation, we utilize the time evolving block decimation (TEBD) algorithm, which is an extension of the density matrix renormalization group and provides a well-controlled method for 1D systems. We show that the positive-U GHM, when hole-doped from half-filling, exhibits a phase with coexistence of quasi-long-range superfluid and charge-density-wave orders. This feature is different from the property of the conventional Hubbard model with positive-U, indicating the particle-assisted tunnelling mechanism in GHM brings in qualitatively new physics.