Enhanced pairing in the checkerboard Hubbard ladder

Karakonstantakis, George; Berg, Erez; White, Steven R.; Kivelson, Steven A.

doi:10.1103/physrevb.83.054508

Cited by 31 publications

(44 citation statements)

References 25 publications

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“…Exact diagonalization of the 4 × 4 site system [10] has found a substantial maximum of the pair-binding energy at t ′ /t ≈ 0.5, U/t ≈ 8 and low hole doping. A similar pairing maximum, occurring at intermediate inhomogeneity levels t ′ /t ≈ 0.5−0.7 and interaction strengths U/t ≈ 5 − 8, was subsequently found in larger plaquette systems using the contractor renormalization (CORE) [11] and DMRG [12] methods. Furthermore, by calculating the other necessary ingredient for superconductivity, namely phase stiffness, these studies have provided evidence that optimal inhomogeneity likely exists also for the superconducting transition temperature, T c , and not just for the pairing scale.…”

Section: Introductionsupporting

confidence: 60%

Optimal inhomogeneity for pairing in Hubbard systems with next-nearest-neighbor hopping

2017

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Previous studies have shown that bipartite Hubbard systems with inhomogeneous hopping amplitudes can exhibit higher pair-binding energies than the uniform model. Here we examine whether this result holds for systems with a more generic band structure. To this end, we use exact diagonalization and the density matrix renormalization group method to study the 4 × 4 Hubbard cluster and the two-leg Hubbard ladder with checkerboard-modulated nearest-neighbor hopping, t, and next-nearest-neighbor (diagonal) hopping, t d . We find that the strongest pairing continues to occur at an intermediate level of inhomogeneity. While the maximal pair-binding energy is enhanced by a positive t d /t, it is suppressed and appears at weaker repulsion strengths and smaller hole concentrations when t d /t is negative. We point out a possible connection between the pairing maximum and the magnetic properties of the system.

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Section: Introductionsupporting

confidence: 60%

Optimal inhomogeneity for pairing in Hubbard systems with next-nearest-neighbor hopping

2017

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“…Other examples are the 'plaquette' model studied by Scalapino 52 , Kivelson, 53 and others, [54][55][56][57]66 as a description of superconductivity arising from pair binding on 2 × 2 plaquettes, and the 1/5-depleted square lattice 23,58,59 for which the results in the left panel of Fig. 12 show the improvement of the sign by increasing the inter-plaquette hopping t ′ from zero.…”

Section: Spatial Entanglementmentioning

confidence: 99%

Geometry dependence of the sign problem in quantum Monte Carlo simulations

2015

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The sign problem is the fundamental limitation to quantum Monte Carlo simulations of the statistical mechanics of interacting fermions. Determinant quantum Monte Carlo (DQMC) is one of the leading methods to study lattice models such as the Hubbard Hamiltonian, which describe strongly correlated phenomena including magnetism, metal-insulator transitions, and (possibly) exotic superconductivity. Here, we provide a comprehensive dataset on the geometry dependence of the DQMC sign problem for different densities, interaction strengths, temperatures, and spatial lattice sizes. We supplement these data with several observations concerning general trends in the data, including the dependence on spatial volume and how this can be probed by examining decoupled clusters, the scaling of the sign in the vicinity of a particle-hole symmetric point, and the correlation between the total sign and the signs for the individual spin species.

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“…In this paper, we use the tunability of the t-J -V -W Hamiltonian to find parameter regimes supporting robust d-wave superfluidity in one-and two-dimensional systems of weakly coupled plaquettes [33][34][35][36][37][38]. Furthermore, we demonstrate that this solvable limit and the associated d-wave superfluidity are experimentally realizable.…”

Section: Introductionmentioning

confidence: 99%

“…In order to construct robust d-wave superfluids at 3/4 filling (three molecules per plaquette), we would like it to be energetically favorable for two holes to condense on the same plaquette. This condition is achieved if the binding energy of two holes [33][34][35][36][37][38] is positive, where E g (n) is the energy of the ground state of |n .…”

Section: Representation Symmetriesmentioning

confidence: 99%

d-wave superfluidity in optical lattices of ultracold polar molecules

2011

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Recent work on ultracold polar molecules, governed by a generalization of the t-J Hamiltonian, suggests that molecules may be better suited than atoms for studying d-wave superfluidity due to stronger interactions and larger tunability of the system. We compute the phase diagram for polar molecules in a checkerboard lattice consisting of weakly coupled square plaquettes. In the simplest experimentally realizable case where there is only tunneling and an XX-type spin-spin interaction, we identify the parameter regime where d-wave superfluidity occurs. We also find that the inclusion of a density-density interaction destroys the superfluid phase and that the inclusion of a spin-density or an Ising-type spin-spin interaction can enhance the superfluid phase. We also propose schemes for experimentally realizing the perturbative calculations exhibiting enhanced d-wave superfluidity.

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Enhanced pairing in the checkerboard Hubbard ladder

Cited by 31 publications

References 25 publications

Optimal inhomogeneity for pairing in Hubbard systems with next-nearest-neighbor hopping

Optimal inhomogeneity for pairing in Hubbard systems with next-nearest-neighbor hopping

Geometry dependence of the sign problem in quantum Monte Carlo simulations

d-wave superfluidity in optical lattices of ultracold polar molecules

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