The ground state of the bose-hubbard model is a supersolid

TL;DR

This paper challenges the conventional view by demonstrating that the Bose-Hubbard model's ground state cannot be a perfect Mott insulator and suggests it may instead be a supersolid with vortex-like phase fluctuations.

Contribution

It provides a new perspective on the ground state of the Bose-Hubbard model, proposing that it is not a Mott insulator but possibly a supersolid with unique phase fluctuation characteristics.

Findings

The ground state cannot be a perfect Mott insulator.

The low-energy spectrum involves vortex-like phase fluctuations.

The question of whether the ground state is necessarily commensurate remains open.

Abstract

The Bose-Hubbard model is well-defined description of a Bose solid which may be realistic for cold atoms in a periodic optical lattice. We show that contrary to accepted theories it can never have as a ground state a perfect Mott insulator solid and that it has a low-energy spectrum of vortex-like phase fluctuations. Whether the ground state is necessarily commensurate remains an open question.