Composite pairing and superfluidity in a one-dimensional resonant Bose-Fermi mixture

TL;DR

This paper investigates the ground-state phases of a one-dimensional resonant Bose-Fermi mixture, revealing a phase with composite superfluidity due to molecular coupling and low-energy excitation gaps.

Contribution

It introduces a bosonization approach and renormalization group analysis to characterize the phase diagram of resonant Bose-Fermi mixtures with equal particle densities.

Findings

Identification of a phase with composite superfluid or pairing correlations

Derivation of an effective low-energy Hamiltonian similar to coupled Tomonaga-Luttinger liquids

Mapping of the phase diagram showing depletion transitions and superfluid phases

Abstract

We study the ground-state properties of one-dimensional mixtures of bosonic and fermionic atoms resonantly coupled to fermionic Feshbach molecules. When the particle densities of fermionic atoms and Feshbach molecules differ, the system undergoes various depletion transitions between binary and ternary mixtures, as a function of the detuning parameter. However, when the particle densities of fermionic atoms and Feshbach molecules are identical, the molecular conversion and disassociation processes induce a gap in a sector of low-energy excitations, and the remaining system can be described by a two-component Tomonaga-Luttinger liquid. Using a bosonization scheme, we derive the effective low-energy Hamiltonian for the system, which has a similar form as that of the two-chain problem of coupled Tomonaga-Luttinger liquids. With the help of improved perturbative renormalization group analysis of the latter problem, we determine the ground-state phase diagram and find that it contains a phase dominated by composite superfluid or pairing correlations between the open and closed resonant channels.