Worm quantum Monte-Carlo study of phase diagram of extended Jaynes-Cummings-Hubbard model

TL;DR

This study uses large-scale worm quantum Monte-Carlo simulations to explore the phase diagram of the extended Jaynes-Cummings-Hubbard model across different geometries, identifying a stable light supersolid phase only on triangular lattices.

Contribution

It provides the first detailed phase diagrams of the extended Jaynes-Cummings-Hubbard model on various lattices, revealing the existence of a stable light supersolid phase on triangular lattices.

Findings

No stable supersolid phase in 1D and square lattices.

Stable light supersolid phase found in triangular lattices.

Soliton and beats observed in finite chains, not indicating true supersolidity.

Abstract

Herein, we study the extended Jaynes-Cummings-Hubbard model mainly by the large-scale worm quantum Monte-Carlo method to check whether or not a light supersolid phase exists in various geometries, such as the one-dimensional chain, square lattices and triangular lattices. To achieve our purpose, the ground state phase diagrams are investigated. For the one-dimensional chain and square lattices, a first-order transition occurs between the superfluid phase and the solid phase and therefore there is no stable supersolid phase existing in these geometries. Interestingly, soliton/beats of the local densities arise if the chemical potential is adjusted in the finite-size chain. However, this soliton-superfluid coexistence can not be considered as a supersolid in the thermodynamic limit. Searching for a light supersolid, we also studied the Jaynes-Cummings-Hubbard model on triangular lattices, and the phase diagrams are obtained. Through measurement of the structural factor, momentum distribution and superfluid stiffness for various system sizes, a supersolid phase exists stably in the triangular lattices geometry and the regime of the supersolid phase is smaller than that of the mean field results. The light supersolid in the Jaynes-Cummings-Hubbard model is attractive because it has superreliance, which is absent in the pure Bose-Hubbard model. We believe the results in this paper could help search for new novel phases in cold-atom experiments