Pair Superfluidity of Three-Body Constrained Bosons in Two Dimensions

TL;DR

This paper investigates the phase diagram and quantum phase transitions of two-dimensional lattice bosons with three-body constraints, revealing a tricritical point and BKT transition characteristics through quantum Monte Carlo simulations.

Contribution

It provides the first detailed analysis of the phase diagram and critical phenomena of three-body constrained bosons in two dimensions using quantum Monte Carlo methods.

Findings

Existence of a tricritical point where the transition changes from first-order to continuous.

Identification of a BKT transition with anomalous stiffness jump.

Characterization of the superfluid-insulator transition in the system.

Abstract

We examine the equilibrium properties of lattice bosons with attractive on-site interactions in the presence of a three-body hard-core constraint that stabilizes the system against collapse and gives rise to a dimer superfluid phase formed by virtual hopping processes of boson pairs. Employing quantum Monte Carlo simulations, the ground state phase diagram of this system on the square lattice is analyzed. In particular, we study the quantum phase transition between the atomic and dimer superfluid regime and analyze the nature of the superfluid-insulator transitions. Evidence is provided for the existence of a tricritical point along the saturation transition line, where the transition changes from being first-order to a continuous transition of the dilute bose gas of holes. The Berzinskii-Kosterlitz-Thouless transition from the dimer superfluid to the normal fluid is found to be consistent with an anomalous stiffness jump, as expected from the unbinding of half-vortices.