Stable-unstable transition for a Bose-Hubbard chain coupled to an environment

TL;DR

This paper investigates how a Bose-Hubbard chain's stability is affected by coupling to an environment, revealing a critical interaction strength where the system transitions from stable to unstable due to a charge gap opening.

Contribution

It identifies a novel stable-unstable transition in a Bose-Hubbard chain coupled to a bosonic bath, distinct from the superfluid-Mott insulator transition, explained by charge gap formation.

Findings

System loses bosons above a critical interaction.

Transition differs from superfluid-Mott insulator transition.

Accurate simulations reveal many-body origin of the transition.

Abstract

Interactions in quantum systems may induce transitions to exotic correlated phases of matter which can be vulnerable to coupling to an environment. Here, we study the stability of a Bose-Hubbard chain coupled to a bosonic bath at zero and non-zero temperature. We show that only above a critical interaction the chain loses bosons and its properties are significantly affected. The transition is of a different nature than the superfluid-Mott insulator transition and occurs at a different critical interaction. We explain such a stable-unstable transition by the opening of a charge gap. The comparison of accurate matrix product state simulations to approximative approaches that miss this transition reveals its many-body origin.