Variational wavefunction study of the triangular lattice supersolid

TL;DR

This paper introduces a variational wavefunction model for the supersolid state of hard-core bosons on a triangular lattice, accurately capturing density deviations and order parameters.

Contribution

It proposes a novel variational wavefunction that exactly evaluates properties and explains supersolid behavior on a triangular lattice.

Findings

Exact evaluation of the wavefunction properties

Prediction of spontaneous density deviation from half-filling

Accurate estimate of the solid order parameter

Abstract

We present a variational wavefunction which explains the behaviour of the supersolid state formed by hard-core bosons on the triangular lattice. The wavefunction is a linear superposition of {\em only and all} configurations minimising the repulsion between the bosons (which it thus implements as a hard constraint). Its properties can be evaluated exactly--in particular, the variational minimisation of the energy yields (i) the surprising and initially controversial spontaneous density deviation from half-filling (ii) a quantitatively accurate estimate of the corresponding density wave (solid) order parameter.