Revisiting a stability problem of two-component quantum droplets
P. Ziń, Maciej Pylak, Mariusz Gajda
Abstract
We study the problem of the stability of a two-component droplet. The standard solution [D. S. Petrov, Phys. Rev. Lett. 115, 155302 (2015)] is based on a particular form of the mean field energy functional, in particular on the assumption of vanishing of potentially large hard-mode-source energy contribution. This imposes a constraint on the densities of the two components. The problem is reduced to stability analysis of a one-component system. As opposed to this, we present a two-component approach including possible nonzero hard-mode-source energy. We minimize the energy under conditions corresponding to the experimentally relevant situation where volume is free and atoms can evaporate. For the specific case of a two-component Bose-Bose droplet we find approximate analytic solutions and compare them to the standard result. We show that the densities of a stable droplet are limited to a range depending on interaction strength, in contrast to the original unique solution.