Steady-state skin effect in bosonic topological edge states under parametric driving

TL;DR

This paper demonstrates a quantum steady-state skin effect in bosonic topological edge states induced by parametric driving, revealing non-Hermitian phenomena without dissipation and highlighting bosonic quantum features.

Contribution

It introduces a novel non-Hermitian skin effect in quantum bosonic systems via parametric pumping, bridging non-Hermitian mathematics and quantum physics.

Findings

Steady-state skin effect observed in bosonic edge states

Corner particle accumulation shows quadrature anisotropy

Non-Hermitian effects achieved without dissipation

Abstract

Non-Hermitian systems have attracted significant theoretical interest due to their extreme properties. However, realizations have mostly been limited to classical applications or artificial setups. In this study, we focus on the quantum nature inherent in bosonic Bogoliubov-de Gennes (BdG) systems, which from the perspective of spectral theory corresponds to non-Hermiticity. Based on this insight, we propose a steady-state skin effect in quantum condensed matter utilizing such BdG non-Hermiticity. Specifically, we introduce BdG quantum terms arising from parametric pumping to the edge states of an underlying bosonic Hermitian Chern insulator, thereby realizing non-Hermiticity without dissipation. This system design has the advantage of being largely independent of microscopic model details. Through analysis using non-equilibrium Green's functions, we find that under open boundary conditions, a steady state exhibiting the non-Hermitian skin effect is realized. The pronounced corner particle accumulation observed in this steady state shows quadrature anisotropy, which manifests the bosonic quantum nature. Our results bridge the gap between the fascinating mathematics of non-Hermitian matrices and practical quantum physical systems.