Effects of finite temperature on the robustness of the Mott insulator phase in pseudo one-dimensional Bose-Hubbard Model

TL;DR

This paper investigates how finite temperature impacts the stability of the Mott insulator phase in a pseudo one-dimensional Bose-Hubbard model, revealing that excited states weaken interactions and reduce the phase's robustness.

Contribution

It introduces the effect of excited states at finite temperature on the Mott insulator phase within a pseudo one-dimensional Bose-Hubbard model, highlighting the phase's decreased stability.

Findings

Mott lobes shrink in the phase diagram at finite temperature

Interactions involving excited states weaken the MI phase

Finite temperature increases in-site particle dispersion

Abstract

We study the superfluid-Mott insulator (SF-MI) transition in an one-dimensional optical lattice system, and employ the Bose-Hubbard model in two dimension with a combined potential of an optical lattice in one direction and a confining harmonic trap in the other direction, which we refer to as the pseudo one-dimension Bose-Hubbard model. There some excited states with respect to the harmonic trap are considered. The Mott lobes shrink in the $\mu$ and $J$ directions of the $\mu$-$J$ phase diagram. The shrinkage occurs because the interactions involving the excited states become weaker than that between particles in the ground state. The dispersion of the in-site particle increases because the energy spacing between the eigenstates of the Hamiltonian decreases at finite temperature. The excited states significantly affect the robustness of the MI phase at finite temperate.