Global phase diagram of three-dimensional extended Boson Hubbard model - a continuous time Quantum Monte Carlo study

TL;DR

This study maps the comprehensive phase diagram of the three-dimensional extended Boson Hubbard model using quantum Monte Carlo simulations, revealing various phase transitions and the existence of a supersolid phase under specific conditions.

Contribution

It provides the first detailed global phase diagram of the 3D extended Boson Hubbard model, identifying phase boundaries and the conditions for supersolid phases.

Findings

Continuous transition from Mott to superfluid phase without symmetry breaking.

Existence of a supersolid phase with density less than 1/2.

First-order transition between Mott and CDW phases.

Abstract

We present the global phase diagram of the extended boson Hubbard model on a simple cubic lattice by quantum Monte Carlo simulation with worm update algorithm. Four kinds of phases are supported by this model, including superfluid, supersolid, Mott, and charge density wave (CDW) states, which are identified in the phase diagram of chemical potential $\mu$ versus nearest neighbor interaction V . By changing the chemical potential, a continuous transition is found from the Mott phase to a superfluid phase without breaking the translational symmetry. For an insulating CDW state, adding particles to it gives rise to a continuous transition to a supersolid phase, while removing particles usually leads to a first-order one to either supersolid or superfluid phase. By tuning the nearest neighbor interaction, one can realize the transition between two insulating phases, Mott and CDW with the same particle density, which turns out to be of the first-order. We also demonstrate that a supersolid phase with average particle density less than 1/2 can exist in a small region of $\mu$ - V phase diagram.