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.
Highlights
The combination of Feshbach resonance and optical-lattice techniques has opened up possibilities for investigating strongly interacting ultracold atoms under tunable configurations [1]
New Journal of Physics 10 (2008) 073007 1367-2630/08/073007+07$30.00 for the repulsive conventional (Fermi–)Hubbard model the susceptibility for superfluid and charge-density-wave (CDW) orders are suppressed at low temperatures and the leading quasi-long-range (QLR) order is given by a spin density wave (SDW) at any filling fraction [6]
In contrast to the case of the conventional positive-U Hubbard model, we show that the superfluid and CDW emerge as dominant QLR orders over spin orders for the positive-U general Hubbard model (GHM) when the system is significantly hole-doped below halffilling, at or very close to half-filling, the dominant correlation in GHM is still antiferromagnetic
Summary
The combination of Feshbach resonance and optical-lattice techniques has opened up possibilities for investigating strongly interacting ultracold atoms under tunable configurations [1]. In this work, we show that coexistence of QLR superfluid and CDW orders can be observed for fermionic atoms with repulsive on-site interaction in an anisotropic optical lattice near a wide Feshbach resonance.
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