Current reversals and metastable states in the infinite Bose-Hubbard chain with local particle loss

TL;DR

This paper introduces a combined quantum trajectory and density-matrix renormalization group algorithm to study long-time dynamics in an open Bose-Hubbard chain, revealing current reversals and metastable states due to many-body interactions.

Contribution

It develops a novel computational method for infinite open quantum systems and uncovers unexpected long-time behaviors in the Bose-Hubbard model with local particle loss.

Findings

Local particle currents reverse direction far from the lossy site.

Metastable states with currents pointing away from the dissipative site form.

Reversal explained by holon-doublon pair creation and escape dynamics.

Abstract

We present an algorithm which combines the quantum trajectory approach to open quantum systems with a density-matrix renormalization group scheme for infinite one-dimensional lattice systems. We apply this method to investigate the long-time dynamics in the Bose-Hubbard model with local particle loss starting from a Mott-insulating initial state with one boson per site. While the short-time dynamics can be described even quantitatively by an equation of motion (EOM) approach at the mean-field level, many-body interactions lead to unexpected effects at intermediate and long times: local particle currents far away from the dissipative site start to reverse direction ultimately leading to a metastable state with a total particle current pointing away from the lossy site. An alternative EOM approach based on an effective fermion model shows that the reversal of currents can be understood qualitatively by the creation of holon-doublon pairs at the edge of the region of reduced particle density. The doublons are then able to escape while the holes move towards the dissipative site, a process reminiscent---in a loose sense---of Hawking radiation.