Quantum droplets in one-dimensional mixtures of quasi Bose-Einstein condensates and Tonks-Girardeau gases

TL;DR

This paper demonstrates that kinetic energy in a one-dimensional mixture of a quasi-BEC and a Tonks-Girardeau gas can stabilize quantum droplets against collapse, revealing a new mechanism for droplet formation in low-dimensional quantum gases.

Contribution

It introduces a novel stabilization mechanism for quantum droplets based on kinetic energy in a 1D mixture, extending understanding beyond Lee-Huang-Yang corrections.

Findings

Kinetic energy can prevent collapse in 1D mixtures.

Identification of low-density and high-density droplet regimes.

Transition from mixture to droplet phase is third order.

Abstract

While binary atomic Bose-Einstein condensates are typically prone to collapse under strong interspecies attraction, it has been shown that higher-order fluctuation corrections, known as Lee-Huang-Yang corrections, can stabilize the mixture. In this work, we demonstrate an alternative stabilization mechanism based on kinetic energy. Specifically, we consider a one-dimensional mixture of a quasi-BEC and a Tonks-Girardeau gas, and show that the kinetic energy of the TG component can counteract the interspecies attraction, thereby preventing collapse. This balance leads to the formation of a self-bound quantum droplet, which exhibits two distinct regimes: a low-density and a high-density droplet. We argue that these regimes are smoothly connected by a crossover. Furthermore, an analysis of the derivatives of the ground state energy reveals that the transition from a miscible mixture to the droplet phase is of third order. Our findings extend the theoretical understanding of quantum droplets in low-dimensional quantum gases, and the proposed system is experimentally accessible within current ultracold atom platforms.