Striped Ultradilute Liquid of Dipolar Bosons in Two Dimensions

TL;DR

This paper explores the formation of a self-bound, striped phase in a two-dimensional dipolar Bose-Einstein condensate, highlighting the role of dipole tilting and quantum fluctuations in stabilizing and modulating the system.

Contribution

It introduces a variational hypernetted-chain approach to analyze the ground state of dipolar bosons, capturing quantum fluctuations non-perturbatively and predicting conditions for striped phase formation.

Findings

Identification of conditions for self-bound phase stability.

Prediction of stripe formation due to dipole tilting.

Demonstration of a non-perturbative method for strongly correlated systems.

Abstract

We investigate the phases of a Bose-Einstein condensate of dipolar atoms restricted to move in a two-dimensional plane. The dipole moments are all aligned in a direction tilted with respect to the plane normal. As a result of the attractive and repulsive components of the dipole-dipole interaction, the dipolar gas has a self-bound phase, which is stabilized by quantum fluctuations. Furthermore, tilting the dipoles tunes the anisotropy of the dipole-dipole interaction, which can trigger a spatial density modulation. In this work we study these two aspects and investigate the conditions for the formation of a self-bound and striped phase, which has been realized in experiments with dipolar droplets. We use a variational method based on the hypernetted-chain Euler-Lagrange optimization of a Jastrow-Feenberg ansatz for the many-body wave function to study the ground state properties. This method takes into account quantum fluctuations in a non-perturbative way and thus can be used also for strongly correlated systems.