Dynamics of equilibration and collisions in ultradilute quantum droplets

TL;DR

This study uses advanced density-functional theory to analyze how ultradilute quantum droplets of potassium behave during equilibration and collisions, revealing the importance of initial population ratios and three-body losses.

Contribution

It provides a comprehensive three-dimensional analysis of quantum droplet collisions considering non-optimal initial ratios and three-body loss effects, which were not addressed in prior work.

Findings

Good agreement with experiments for non-optimal initial ratios

Three-body loss effects vary significantly depending on the state

Initial population ratio influences collision outcomes

Abstract

Employing time-dependent density-functional theory, we have studied dynamical equilibration and binary head-on collisions of quantum droplets made of a $^{39}$K-$^{39}$K Bose mixture. The phase space of collision outcomes is extensively explored by performing fully three-dimensional calculations with effective single-component QMC based and two-components LHY-corrected mean-field functionals. We exhaustively explored the important effect -- not considered in previous studies -- of the initial population ratio deviating from the optimal mean-field value $N_2/N_1 = \sqrt{a_{11} / a_{22}}$. Both stationary and dynamical calculations with an initial non-optimal concentration ratio display good agreement with experiments. Calculations including three-body losses acting only on the $\left|F, m_{F}\right\rangle=|1,0\rangle$ state show dramatic differences with those obtained with the three-body term acting on the total density.