Quantum Phases of Soft-Core Dipolar Bosons in Optical Lattices

TL;DR

This paper investigates the phase diagram of soft-core dipolar bosons in a 2D optical lattice, revealing various solid, supersolid, and pair phases through quantum Monte Carlo simulations, and discusses experimental observability.

Contribution

It provides the first comprehensive phase diagram including full dipolar interactions and identifies new mechanisms for stabilizing supersolid phases.

Findings

Supersolid phases are stabilized by both particle and hole doping.

The study maps out the stability of quantum phases against temperature.

It discusses conditions for observing pair checkerboard phases experimentally.

Abstract

We study the phase diagram of a system of soft-core dipolar bosons confined to a two-dimensional optical lattice layer. We assume that dipoles are aligned perpendicular to the layer such that the dipolar interactions are purely repulsive and isotropic. We consider the full dipolar interaction and perform Path Integral Quantum Monte Carlo simulations using the Worm Algorithm. Besides a superfluid phase, we find various solid and supersolid phases. We show that, unlike what was found previously for the case of nearest-neighboring interaction, supersolid phases are stabilized not only by doping the solids with particles but with holes as well. We further study the stability of these quantum phases against thermal fluctuations. Finally, we discuss pair formation and the stability of the pair checkerboard phase formed in a bilayer geometry, and suggest experimental conditions under which the pair checkerboard phase can be observed.