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Superconductivity and Trimer Formation in Attractive Hubbard Ladders
We investigate the interplay between superconducting correlations and trimer formation in polarized two-component Fermi gases confined to multileg attractive Hubbard ladders. Using density-matrix renormalization group (DMRG) simulations, we examine the effects of spin-dependent tunneling amplitudes on these systems. Specifically, we analyze how bound states of three fermions (trimers) influence Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) superconducting correlations at commensurate charge carrier densities, where .
In one-dimensional (1D) systems, trimer formation is known to suppress FFLO correlations exponentially. Our results show that this suppression persists in narrow ladder lattices, effectively mirroring the 1D behavior. However, we observe a striking departure from the 1D regime as the ladder width increases. For ladders with four legs, the impact of trimers on superconducting correlations becomes negligible, suggesting that wider systems host a distinct environment where FFLO-like pairing remains robust even in the presence of trimer states.
These findings highlight the dimensional crossover in Hubbard systems and elucidate the mechanisms governing superconductivity and bound-state formation in strongly correlated fermionic systems. Our work has implications for understanding unconventional superconductivity in such systems.