Quantum droplets with particle imbalance in one-dimensional optical lattices

TL;DR

This paper investigates how particle imbalance affects the formation and properties of quantum droplets in a one-dimensional optical lattice with a binary bosonic mixture, revealing phenomena like particle expulsion and super Tonks-Girardeau gas formation.

Contribution

It introduces a detailed analysis of particle-imbalanced quantum droplets using DMRG simulations, highlighting the interplay between bound states and unpaired particles in one-dimensional systems.

Findings

Quantum droplets can sustain small particle imbalances with effective magnetization.

Beyond a critical imbalance, excess particles are expelled from the droplet.

Unpaired particles form a super Tonks-Girardeau gas at the expulsion point.

Abstract

We study the formation of particle-imbalanced quantum droplets in a one-dimensional optical lattice containing a binary bosonic mixture at zero temperature. To understand the effects of the imbalance from both the few- and many-body perspectives, we employ density matrix renormalization group (DMRG) simulations and perform the extrapolation to the thermodynamic limit. In contrast to the particle-balanced case, not all bosons are paired, resulting in an interplay between bound states and individual atoms that leads to intriguing phenomena. Quantum droplets manage to sustain a small particle imbalance, resulting in an effective magnetization. However, as the imbalance is further increased, a critical point is eventually crossed, and the droplets start to expel the excess particles while the magnetization in the bulk remains constant. Remarkably, the unpaired particles on top of the quantum droplet effectively form a super Tonks-Girardeau (hard-rod) gas. The expulsion point coincides with the critical density at which the size of the super Tonks-Girardeau gas matches the size of the droplet.