Quantum-Phase Transitions of Interacting Bosons and the Supersolid Phase

TL;DR

This paper explores the phase diagram of strongly interacting bosons in two dimensions, revealing superfluid, Mott insulator, charge-density wave, and supersolid phases, along with critical exponents for phase transitions.

Contribution

It introduces a comprehensive analysis combining mean-field, variational, and Monte Carlo methods to identify and characterize a supersolid phase in two-dimensional bosonic systems.

Findings

Identification of a stable supersolid phase with coexisting orders

Mapping of the phase diagram including superfluid, Mott insulator, and charge-density wave phases

Determination of critical exponents for phase transitions

Abstract

We investigate the properties of strongly interacting bosons in two dimensions at zero temperature using mean-field theory, a variational Ansatz for the ground state wave function, and Monte Carlo methods. With on-site and short-range interactions a rich phase diagram is obtained. Apart from the homogeneous superfluid and Mott-insulating phases, inhomogeneous charge-density wave phases appear, that are stabilized by the finite-range interaction. Furthermore, our analysis demonstrates the existence of a supersolid phase, in which both long-range order (related to the charge-density wave) and off-diagonal long-range order coexist. We also obtain the critical exponents for the various phase transitions.