Asymmetric transmission through a flux-controlled non-Hermitian scattering center

TL;DR

This paper investigates how a flux-controlled non-Hermitian scattering center can act as a quantum diode, enabling asymmetric transmission at specific energies, with potential applications in non-Hermitian quantum systems.

Contribution

It introduces a novel flux-controlled non-Hermitian scattering scheme that achieves perfect unidirectional transmission at spectral singularities, advancing non-Hermitian quantum diode design.

Findings

A PT-symmetric scattering center has symmetric transmission despite internal unidirectional dynamics.

The proposed flux-controlled triangular ring acts as a diode at spectral singularity energies.

The system exhibits perfect unidirectionality and relates to reflectionless absorption phenomena.

Abstract

We study the possibility of asymmetric transmission induced by a non-Hermitian scattering center embedded in a one-dimensional waveguide, motivated by the aim of realizing quantum diode in a non-Hermitian system. It is shown that a $\mathcal{PT}$ symmetric non-Hermitian scattering center always has symmetric transmission although the dynamics within the isolated center can be unidirectional, especially at its exceptional point. We propose a concrete scheme based on a flux-controlled non-Hermitian scattering center, which comprises a non-Hermitian triangular ring threaded by an Aharonov-Bohm flux. The analytical solution shows that such a complex scattering center acts as a diode at the resonant energy level of the spectral singularity, exhibiting perfect unidirectionality of the transmission. The connections between the phenomena of the asymmetric transmission and reflectionless absorption are also discussed.