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Pairing and Pair Superfluid Density in One-Dimensional Two-Species Fermionic and Bosonic Hubbard Models
B Grémaud1,2,3, G G Batrouni2,3,4,5
1Aix-Marseille Univ, Université de Toulon, CNRS, CPT, IPhU, AMUtech, Marseille, France.
Physical Review Letters
|July 23, 2021
Summary
Pair superfluidity in 1D optical lattices arises solely from bound pairs, not individual atoms. This Bardeen-Cooper-Schrieffer (BCS) pairing behavior, especially under weak attraction, is critical for understanding superfluid properties.
Area of Science:
- Quantum physics
- Condensed matter physics
- Ultracold atoms
Background:
- Superfluidity in quantum systems is a key phenomenon.
- Understanding the role of interspecies interactions is crucial.
- Previous studies have debated the nature of superfluidity in attractive systems.
Purpose of the Study:
- To investigate the onset and properties of pair superfluidity in 1D optical lattices.
- To compare fermionic and bosonic systems with onsite interspecies attraction.
- To clarify the contributions of pairs versus individual species to superfluidity.
Main Methods:
- Unbiased computational methods, including quantum Monte Carlo (QMC) and density matrix renormalization group (DMRG).
- Analysis of the Drude weight tensor and winding numbers to establish a correspondence between QMC and DMRG results.
- Comparison with repulsive interaction cases and soft-core bosons.
Main Results:
- Pairs are the sole contributors to superfluidity in attractive systems, with no individual species contributions.
- Weak attraction leads to exponentially diverging pair sizes (Bardeen-Cooper-Schrieffer pairing), a factor often overlooked.
- Results contradict previous claims of drag superfluidity and symmetry between attractive and repulsive interactions.
- Similar pair-only superfluidity is observed in soft-core bosons.
Conclusions:
- Pair formation is essential for superfluidity in these 1D systems, regardless of whether they are fermionic or bosonic.
- Accurate characterization requires accounting for large pair sizes in weakly attractive regimes.
- The study provides a refined understanding of superfluidity mechanisms in interacting quantum systems.
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