Abstract
We report on the dynamical formation of self-bound quantum droplets in attractive mixtures of $^{39}$K atoms. Considering the experimental observations of Semeghini et al., Phys. Rev. Lett. 120, 235301 (2018), we perform numerical simulations to understand the relevant processes involved in the formation of a metastable droplet from an out-of-equilibrium mixture. We first analyze the so-called self-evaporation mechanism, where the droplet dissipates energy by releasing atoms, and then we consider the effects of losses due to three-body recombinations and to the balancing of populations in the mixture. We discuss the importance of these three mechanisms in the observed droplet dynamics and their implications for future experiments.
Highlights
Self-bound droplets of ultracold atoms were recently discovered as a new exotic quantum phase [1,2,3,4]
We report on the dynamical formation of self-bound quantum droplets in attractive mixtures of 39K atoms
We have verified that the regime of its occurrence corresponds to that predicted in Ref. [1], and we have discussed how and on which timescales this mechanism allows the dissipation of energy in the droplet
Summary
Self-bound droplets of ultracold atoms were recently discovered as a new exotic quantum phase [1,2,3,4]. The first pioneering experiments performed with homonuclear mixtures at ICFO (Institut de Ciencies Fotoniques) [9,12] and LENS (the European Laboratory for Non-Linear Spectroscopy) [10,13] were able to demonstrate the existence of self-bound droplets in these systems and to provide a first characterization of their peculiar features While these works were mainly devoted to study the droplets’ equilibrium properties, the experiment reported in Ref. Calculating the excitation spectrum of the droplet, Petrov noticed that, in some specific conditions, the droplet cannot host any discrete excitation, since all the excited states are higher in energy than the particle emission threshold This suggested the idea that the droplet could be able to dissipate any excess of energy by expelling atoms, from which the term self-evaporation originated.
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