Supersolids in the Bose-Hubbard Hamiltonian

TL;DR

This paper investigates the phase diagram of the Bose-Hubbard model with extended interactions, revealing superfluid, solid, and supersolid phases depending on interaction strengths and doping levels.

Contribution

It combines numeric and analytic methods to map out the phase diagram, identifying conditions for supersolid formation in the extended Bose-Hubbard model.

Findings

Solid phases are checkerboard or striped depending on interactions.

Supersolid phases exhibit simultaneous diagonal and off-diagonal order.

No coexistence of superfluidity and solid order at half filling.

Abstract

We use a combination of numeric and analytic techniques to determine the groun d state phase diagram of the Bose--Hubbard Hamiltonian with longer range repulsi ve interactions. At half filling one finds superfluidity and an insulating solid phase. Depending on the relative sizes of near--neighbor and next near--neighbor interactions, this solid either follows a checkerboard or a striped pattern. In neither case is there a coexistence with superfluidity. However upon doping ``supersolid'' phases appear with simultaneous diagonal and off--diagonal long range order.