Flat band in two-dimensional non-Hermitian optical lattices

TL;DR

This paper introduces a method to create real-energy flat bands in 2D non-Hermitian optical lattices, enabling new possibilities for flat band engineering in complex lattice systems.

Contribution

It presents a novel approach to generate flat bands in 2D non-Hermitian lattices by matching synthetic magnetic flux and non-Hermiticity, applicable to various lattice types.

Findings

Real-energy flat bands achieved in 2D non-Hermitian Lieb lattice

Method applicable to Tasaki's decorated square, dice, and kagome lattices

Advances flat band engineering in non-Hermitian optical systems

Abstract

We propose a method to generate a real-energy flat band in a two-dimensional (2D) non-Hermitian Lieb lattice. The coincidence of the flat band eigenstate in both real and momentum spaces is essential for the proposed flat band, which is flexible at the appropriate match between the synthetic magnetic flux and non-Hermiticity. The proposed method is not limited to the 2D non-Hermitian Lieb lattice, and is applied to the 2D non-Hermitian Tasaki's decorated square lattice, dice lattice, and kagome lattice. Our findings make a step forward for the flat band engineering in 2D non-Hermitian optical lattices.