Breakdown of the Mott insulator: Exact solution of an asymmetric Hubbard model

TL;DR

This paper provides an exact solution to an asymmetric Hubbard model to understand how dissipative tunneling causes the breakdown of a Mott insulator, leading to an insulator-metal transition.

Contribution

It introduces an exact solution for the asymmetric Hubbard model with dissipation, revealing the mechanism of Mott insulator breakdown due to tunneling effects.

Findings

Hubbard gap decreases monotonically with increased tunneling

The system undergoes an insulator-metal transition as the gap closes

Comparison with non-Hermitian systems highlights the quantum phase transition

Abstract

The breakdown of the Mott insulator is studied when the dissipative tunneling into the environment is introduced to the system. By exactly solving the one-dimensional asymmetric Hubbard model, we show how such a breakdown of the Mott insulator occurs. As the effect of the tunneling is increased, the Hubbard gap is monotonically decreased and finally disappears, resulting in the insulator-metal transition. We discuss the origin of this quantum phase transition in comparison with other non-Hermitian systems recently studied.