Fragmentation Temperature of 1D and 3D Quantum Droplets in a BEC Mixture

TL;DR

This study investigates how quantum droplets in Bose-Einstein condensate mixtures can fragment at finite temperatures, revealing conditions under which droplets split into smaller droplets or gas, affecting their stability.

Contribution

It introduces the concept of droplet fragmentation at finite temperature and details the conditions leading to splitting in 1D and 3D configurations, a previously unexplored aspect.

Findings

3D droplets split when interspecies interactions are much stronger than intraspecies.

1D droplets fragment without large variation in interaction strengths and at moderate densities.

Rising temperature causes 1D droplets to expel atoms, forming a gas of free atoms and pairs.

Abstract

In a mixture of two Bose-Einstein condensates, the interactions can be tuned such that self-bound objects called quantum droplets appear. Whereas the ground states of such quantum droplets at finite temperature have been studied for three- and one-dimensional configurations, the possible fragmentation of these droplets has so far not been considered in these studies. In this paper, we show that droplets can lower their free energy by splitting or fragmenting in a combination of multiple smaller droplets and/or a gas. Three-dimensional droplets will split when the interspecies interaction strength is considerably stronger than the intraspecies interaction strength, and the number of atoms is of the same order as the minimum number of atoms necessary to form a droplet. One-dimensional droplets will fragment as long as the intraspecies and interspecies interactions strength do not vary too much in strength and the density is not to big compared with the scattering length. If the temperature rises, 1D droplets will split by expelling atoms, forming a gas of predominantly free atoms and pairs of atoms. These pairs remain present in the system up to considerably high temperatures compared to the transition temperature. Our results provide important insights on the stability of these droplets.