Momentum-independent reflectionless transmission in the non-Hermitian time-reversal symmetric system

TL;DR

This paper explores a class of non-Hermitian, time-reversal symmetric systems with real spectra, demonstrating momentum-independent reflectionless transmission and defect invisibility, which could have implications for wave control and topological physics.

Contribution

It introduces a new class of non-Hermitian systems with real spectra based on UHA dimers, showing reflectionless transmission and defect invisibility under certain conditions.

Findings

Achieves momentum-independent reflectionless transmission in non-Hermitian systems.

Demonstrates defect invisibility due to balanced RT dimers.

Shows Hermitian counterparts share topological structures with original systems.

Abstract

We theoretically study the non-Hermitian systems, the non-Hermiticity of which arises from the unequal hopping amplitude (UHA) dimers. The distinguishing features of these models are that they have full real spectra if all of the eigenvectors are time-reversal (T) symmetric rather than parity-time-reversal (PT) symmetric, and that their Hermitian counterparts are shown to be an experimentally accessible system, which have the same topological structures as that of the original ones but modulated hopping amplitudes within the unbroken region. Under the reflectionless transmission condition, the scattering behavior of momentum-independent reflectionless transmission (RT) can be achieved in the concerned non-Hermitian system. This peculiar feature indicates that, for a certain class of non-Hermitian systems with a balanced combination of the RT dimers, the defects can appear fully invisible to an outside observer.