Quantum Monte-Carlo study of a two-species boson Hubbard model

TL;DR

This study uses quantum Monte Carlo simulations to explore supersolid phases in a two-species boson Hubbard model, revealing three distinct superfluid phases and comparing findings with mean-field predictions.

Contribution

First quantum Monte Carlo analysis of a two-species boson Hubbard model demonstrating multiple superfluid phases and phase transition characteristics.

Findings

Identified three distinct superfluid phases at low temperatures.

Compared phase boundaries and transition nature with mean-field theory.

Showed inter-species interactions facilitate vacancy and interstitial condensation.

Abstract

We consider a two-species hard-core boson Hubbard model for a supersolid, where the two types of bosons represent vacancies and interstitials doped into a commensurate crystal. The on-site inter-species interaction may create bound states of vacancies and interstitials facilitating vacancy condensation at lower energies than in a single-species model, as suggested in an earlier mean field study. Here we carry out quantum Monte Carlo simulation to study possible supersolid phases of the model, corresponding to superfluid phases of the vacancies or interstitials. At low temperatures, we find three distinct superfluid phases. The extent of the phases and the nature of the phase transitions are discussed in comparison to mean-field theory.