Persistent supersolid phase of hard-core bosons on the triangular lattice

TL;DR

This paper investigates the phase transition of hard-core bosons on a triangular lattice, revealing a stable supersolid phase that persists across a wide range of interaction strengths, characterized by a specific symmetry-breaking pattern.

Contribution

It demonstrates the existence and stability of a supersolid phase in a triangular lattice model of hard-core bosons, extending previous understanding of quantum phase transitions in such systems.

Findings

Identifies a quantum phase transition at U_c ≈ 4.45 from superfluid to supersolid.

Shows the supersolid phase maintains stability for arbitrarily large U/t.

Characterizes the supersolid as breaking lattice translation symmetry in a √3×√3 pattern.

Abstract

We study hard-core bosons with unfrustrated hopping ($t$) and nearest neighbour repulsion ($U$) on the triangular lattice. At half-filling, the system undergoes a zero temperature ($T$) quantum phase transition from a superfluid phase at small $U$ to a supersolid at $U_c \approx 4.45$ in units of $2t$. This supersolid phase breaks the lattice translation symmetry in a characteristic $\sqrt{3} \times \sqrt{3}$ pattern, and is remarkably stable--indeed, a smooth extrapolation of our results indicates that the supersolid phase persists for arbitrarily large $U/t$.