Flux-Driven Circular Current in a Non-Hermitian Dimerized Aharonov-Bohm Ring: Impact of Physical Gain and Loss

Abstract

In the present theoretical work, we numerically explore magnetic response of a tight-binding dimerized ring subjected to Aharonov-Bohm (AB) flux and environmental interactions. Specifically, we introduce an imaginary site potential on the odd lattice sites to represent physical gain and loss, while the even lattice sites remain unperturbed. We investigate the induced current resulting from the AB flux in both real and imaginary eigenspaces, aiming to enhance this current significantly by adjusting the gain/loss parameter ($d$). Our analysis focuses on how exceptional points in the real and imaginary eigenenergy spaces contribute to notable increases in current at specific $d$ values, and the emergence of purely real current when the imaginary current vanishes. We discuss how the dual behavior of energy spectrum (real and imaginary), converging to and diverging from zero energy, affects the enhancement of the current. Additionally, we study the interplay between the correlations of dimerized hopping integrals and the gain-loss parameter, which affects the current and highlights key features associated with these physical parameters. Furthermore, we consider how system size impacts our findings. Our study may reveal unconventional characteristics in various loop configurations, potentially paving the way for new research directions.