Quantum Monte Carlo study of a two dimensional dipolar Bose gas in a harmonic trap

TL;DR

This study uses Quantum Monte Carlo simulations to explore how the orientation of dipoles affects the structure and superfluid properties of a two-dimensional dipolar Bose gas in a harmonic trap, revealing structural transitions and changes in superfluidity.

Contribution

It provides the first detailed quantum Monte Carlo analysis of dipole orientation effects on 2D Bose gases in traps, including structural and superfluid behavior.

Findings

Vertical dipoles form a shell-structured crystal

Tilting dipoles induces striped structures

Tilting reduces superfluidity

Abstract

We present a Quantum Monte Carlo study of the ground state properties of a two dimensional system of Bose particle with dipole moment in a harmonic trap. The direction of the dipoles is assumed to be fixed by an external field. We study how the system behaves when the direction of the dipole moments is changed. Our analysis is made using Path Integral Monte Carlo simulations in the Grand Canonical ensemble, using the Worm Algorithm. We study systems of increasing size, focusing on the spatial distribution of the atoms inside the trap and on the superfluid fraction of the sample. We find that vertical dipoles form a crystal, characterized by a shell structure, while tilting the dipoles has the effect of inducing a striped structure. We find that similar behaviour can be found in the analogue classical system. Vertical dipoles display nonclassical inertia while a strong tilting decreases superfluidity.