Binding between two-component bosons in one dimension

TL;DR

This paper explores the ground state behaviors of one-dimensional Bose-Bose mixtures under harmonic confinement, revealing conditions for molecular gas formation, condensation, and collapse across varying inter-species interactions.

Contribution

It provides a detailed analysis of the crossover from weak to strong inter-species attraction in 1D Bose mixtures using an exact numerical method, highlighting novel phases and collapse mechanisms.

Findings

Formation of molecular Tonks-Girardeau gas at intermediate interactions

Emergence of molecular condensate at stronger coupling

Collapse to a bound state beyond critical attraction

Abstract

We investigate the ground state of one-dimensional few-atom Bose-Bose mixtures under harmonic confinement throughout the crossover from weak to strong inter-species attraction. The calculations are based on the numerically exact multi-configurational time-dependent Hartree method. For repulsive components we detail the condition for the formation of a molecular Tonks-Girardeau gas in the regime of intermediate inter-species interactions, and the formation of a molecular condensate for stronger coupling. Beyond a critical inter-species attraction, the system collapses to an overall bound state. Different pathways emerge for unequal particle numbers and intra-species interactions. In particular, for mixtures with one attractive component, this species can be viewed as an effective potential dimple in the trap center for the other, repulsive component.