Composite fermionization of 1-D Bose-Bose mixtures

TL;DR

This paper investigates the ground states of one-dimensional Bose-Bose mixtures under harmonic confinement, revealing a crossover from demixed to separated phases as inter-species repulsion increases, with various pathways influenced by system asymmetries.

Contribution

It introduces the concept of composite-fermionization crossover in 1D Bose-Bose mixtures and explores how different parameters affect phase separation and symmetry.

Findings

Demixing occurs at weak intra-species interactions.

Atomic-level separation happens at strong intra-species repulsion.

Profiles become strongly overlapping due to symmetry, sensitive to perturbations.

Abstract

We study the ground states of one-dimensional Bose-Bose mixtures under harmonic confinement. As we vary the inter-species coupling strength up to the limit of infinite repulsion, we observe a generalized, composite-fermionization crossover. The initially coexisting phases demix as a whole (for weak intra-species interactions) and separate on an atomic level (for strong intra-species repulsion). By symmetry, the two components end up with strongly overlapping profiles, albeit sensitive to symmetry-breaking perturbations. Different pathways emerge in case the two components have different atom numbers, different intra-species interactions, or different masses and/or trap frequencies.