Quantum phase transitions from Solids to Supersolids in bi-partite lattices

TL;DR

This paper investigates phase transitions in an extended boson Hubbard model on bipartite lattices, revealing stable supersolids, proposing a new valence bond supersolid, and analyzing the universality class of the transitions.

Contribution

It introduces a new type of supersolid called valence bond supersolid and analyzes the universality class of the phase transitions from solids to supersolids.

Findings

Supersolids are stable near half filling on bipartite lattices.

Proposed a new valence bond supersolid phase.

Transitions belong to the same universality class as Mott insulator to superfluid.

Abstract

We studied some phases and phase transitions in an extended boson Hubbard model slightly away from half filling on bipartite lattices such as honeycomb and square lattice. We find that in the insulating side, different kinds of supersolids are generic stable states slightly away from half filling. We propose a new kind of supersolid: valence bond supersolid. We show that the quantum phase transitions from solids to supersolids driven by a chemical potential are in the same universality class as that from a Mott insulator to a superfluid, therefore have exact exponents $ z=2, \nu=1/2, \eta=0 $ (with logarithmic corrections). Comparisons with previous quantum Monte-Carlo (QMC) simulations on some microscopic models on a square lattice are made. Implications on possible future QMC simulations are given.