Dimer-dimer zero crossing and dilute dimerized liquid in a one-dimensional mixture

TL;DR

This paper investigates the interaction crossover of dimers in a one-dimensional Bose-Bose mixture, revealing a shifted dimer-dimer zero crossing and predicting a stable dilute dimerized liquid phase due to three-dimer forces.

Contribution

It identifies the shifted dimer-dimer zero crossing curve and predicts a new dilute dimerized liquid phase stabilized by three-dimer repulsion.

Findings

Dimer-dimer interaction zero crossing is shifted towards larger intra-species couplings.

The mean-field stability boundary is not accurate for the zero crossing location.

A dilute dimerized liquid phase can exist stabilized by three-dimer forces.

Abstract

We consider the system of dimers formed in a one-dimensional mass-balanced Bose-Bose mixture of species $\sigma=\uparrow$, $\downarrow$ with attractive interspecies and repulsive intraspecies contact interactions. In the plane parametrized by the ratios of the coupling constants $g_{\uparrow\uparrow}/|g_{\uparrow\downarrow}|$ and $g_{\downarrow\downarrow}/|g_{\uparrow\downarrow}|$ we trace out the curve where the dimer-dimer interaction switches from attractive to repulsive. We find this curve to be significantly (by more than a factor of 2) shifted towards larger $g_{\sigma\sigma}$ (or smaller $|g_{\uparrow\downarrow}|$) compared to the mean-field stability boundary $g_{\uparrow\uparrow}g_{\downarrow\downarrow}=g_{\uparrow\downarrow}^2$. For a weak dimer-dimer attraction we predict a dilute dimerized liquid phase stabilized against collapse by a repulsive three-dimer force.