Quartet Superfluid in Two-dimensional Mass-imbalanced Fermi Mixtures

Abstract

Quartet superfluid (QSF) is a distinct type of fermion superfluidity that exhibits high-order correlation beyond the conventional BCS pairing paradigm. In this Letter, we report the emergent QSF in 2D mass-imbalanced Fermi mixtures with two-body contact interactions. This is facilitated by the formation of quartet bound state in vacuum that consists of a light atom and three heavy fermions. For an optimized heavy-light number ratio $3:1$, we identify QSF as the ground state in a considerable parameter regime of mass imbalance and 2D coupling strength. Its unique high-order correlation can be manifested in the momentum-space crystallization of pairing field and density distribution of heavy fermions. Our results can be readily detected in Fermi-Fermi mixtures nowadays realized in cold atoms laboratories, and meanwhile shed light on exotic superfluidity in a broad context of mass-imbalanced fermion mixtures.

7+8 pages, 3+5 figures

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Cited by in corpus (7)

• Quantum mixtures of ultracold gases of neutral atoms
• Ultracold LiCr: a new pathway to quantum gases of paramagnetic polar molecules
• Competing few-body correlations in ultracold Fermi polarons
• Quartet correlations near the surface of $N=Z$ nuclei
• BCS-BEC crossover of the strongly interacting ${}^6$Li-${}^{40}$K mixture
• Dipole-Mode Spectrum and Hydrodynamic Crossover in a Resonantly Interacting Two-Species Fermion Mixture
• Universal clusters in quasi-two-dimensional ultracold Fermi mixtures