Pairing and pair superfluid density in one-dimensional Hubbard models

Abstract

We use unbiased computational methods to elucidate the onset and properties of pair superfluidity in two-species fermionic and bosonic systems with onsite interspecies attraction loaded in one-dimensional optical lattice. We compare results from quantum Monte Carlo (QMC) and density matrix renormalization group (DMRG), emphasizing the one-to-one correspondence between the Drude weight tensor, calculated with DMRG, and the various winding numbers extracted from the QMC. Our results show that, for any nonvanishing attractive interaction, pairs form and are the sole contributors to superfluidity, there are no individual contributions due to the separate species. For weak attraction, the pair size diverges exponentially, i.e. Bardeen-Cooper-Schrieffer (BCS) pairing requiring huge systems to bring out the pair-only nature of the superfluid. This crucial property is largely overlooked in many studies, thereby misinterpreting the origin and nature of the superfluid. We compare and contrast this with the repulsive case and show that the behavior is very different, contradicting previous claims about drag superfluidity and the symmetry of properties for attractive and repulsive interactions. Finally, our results show that the situation is similar for soft core bosons: superfluidity is due only to pairs, even for the smallest attractive interaction strength compatible with the largest system sizes that we could attain.

5 pages, 4 figures

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Cited by in corpus (8)

• Pairing and superconductivity in quasi one-dimensional flat band systems: Creutz and sawtooth lattices
• Superfluidity in the 1D Bose-Hubbard Model
• Designer Flat Bands: Topology and Enhancement of Superconductivity
• Detection of Berezinskii-Kosterlitz-Thouless transition via Generative Adversarial Networks
• Disorder in interacting quasi-one-dimensional systems: flat and dispersive bands
• Competing instabilities at long length scales in the one-dimensional Bose-Fermi-Hubbard model at commensurate fillings
• Nonlocal order parameter of pair superfluids
• Bootstrapping Flat-band Superconductors: Rigorous Lower Bounds on Superfluid Stiffness