Interplay between exotic superfluidity and magnetism in a chain of four-component ultracold atoms

TL;DR

This paper explores the complex interplay of superfluidity and magnetism in a one-dimensional chain of four-component ultracold fermionic atoms, revealing exotic states like inhomogeneous quartet superfluids and phase segregation.

Contribution

It provides a combined analytical and numerical study of competing bound states and magnetic phases in an SU(4) symmetric Hubbard model with novel inhomogeneous superfluid states.

Findings

Discovery of inhomogeneous FFLO-type superfluid of quartets

Identification of a transition to localized quartet molecular states

Observation of spatial segregation between molecular crystals and ferromagnetic liquids

Abstract

We investigate the spin-polarized chain of ultracold fermionic atoms with spin-3/2 described by the fermionic Hubbard model with SU(4) symmetric attractive interaction. The competition of bound pairs, trions, quartets and unbound atoms is studied analytically and by density matrix renormalization group simulations. We find several distinct states where bound particles coexist with the ferromagnetic state of unpaired fermions. In particular, an exotic inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)-type superfluid of quartets in a magnetic background of uncorrelated atoms is found for weaker interactions. We show that the system can be driven from this quartet-FFLO state to a molecular state of localized quartets which is also reflected in the static structure factor. For strong enough coupling, spatial segregation between molecular crystals and ferromagnetic liquids emerges due to the large effective mass of the composite particles.