Tetramers of two heavy and two light bosons

TL;DR

This paper investigates the conditions under which four-boson bound states form due to competing short-range attractive and repulsive forces, with implications for impurity atoms in Bose-Einstein condensates.

Contribution

It provides a theoretical calculation of the critical repulsion strength needed to unbind four-body bosonic states considering mass differences and interaction forces.

Findings

Critical repulsion strength for unbinding four bosons calculated

Conditions for impurity atoms to bind with only one boson identified

Analysis relevant for impurity behavior in Bose-Einstein condensates

Abstract

This article considers the bound states of two heavy and two light bosons, when a short-range force attracts the bosons of different mass, and a short-range force repel the light bosons. The existence of such four-body bound states results from the competition between these two forces. For a given strength of the attraction, the critical strength of the repulsion necessary to unbind the four particles is calculated. This study is motivated by the experimental realisation of impurity atoms immersed in an atomic Bose-Einstein condensate, and aims at determining in which regime only one boson contributes to binding two impurities.