Ground state properties of a homogeneous 2D system of Bosons with dipolar interactions

TL;DR

This paper investigates the ground-state phases of a two-dimensional dipolar Bose system using quantum Monte Carlo methods, revealing a gas-solid transition and signs of supersolidity near the transition.

Contribution

It provides the first quantum Monte Carlo analysis of 2D dipolar bosons, highlighting limitations of mean-field theory and evidence for supersolid behavior.

Findings

Identified a quantum phase transition from gas to solid.

Detected non-zero superfluid fraction in finite-size crystals.

Observed enhancement of superfluidity with vacancies.

Abstract

The ground-state phase properties of a two-dimensional Bose system with dipole-dipole interactions is studied by means of quantum Monte Carlo techniques. Limitations of mean-field theory in a two-dimensional geometry are discussed. A quantum phase transition from gas to solid is found. Crystal is tested for existence of a supersolid in the vicinity of the phase transition. Existence of mesoscopic analogue of the off-diagonal long-range order is shown in the one-body density matrix in a finite-size crystal. Non-zero superfluid fraction is found in a finite-size crystal, the signal being dramatically increased in presence of vacancies.