New Trends of Non-Hermitian Topology in Open and Correlated Quantum Systems

Introduction

Non-Hermiticity plays a central role in describing open systems, which in recent years has been investigated in the context of topology revealing a dramatic enrichment of the phenomenology of topological phases. A particular focus has been on the appearance of truly non-Hermitian (NH) degeneracies known as exceptional points (EPs) at which not only the eigenvalues but also the eigenvectors coalesce.

Phenomena of Exceptional Points

In their most elementary form, EPs reveal intriguing phenomena, such as:

• Unidirectional transmission
• One-sided visibility

Due to the novelty of the field, research has only recently started to dive into the topic of higher-order EPs and the importance of EPs beyond classical systems.

NTopQuant Project Overview

NTopQuant elucidates the role played by exceptional nodal phases in open and correlated quantum systems by providing a new perspective on open quantum materials.

Insights and Understanding

NTopQuant not only paves the way towards gaining profound insights into the properties of higher-order exceptional nodal phases but also expands our understanding of open and correlated quantum systems.

Experimental Connections

Making connections to experiment, NTopQuant studies nonlinear optical systems in close collaboration with experimentalists at the host institute. While EPs are typically realized in coupled systems, we focus on single devices, thus proposing a new path towards studying EPs in optical systems.

Moiré Materials

Equally relevant for experiment are Moiré materials, which are powerful quantum simulators realizing exotic strongly correlated phases. NTopQuant investigates these materials in their open form, which not only results in a new research direction but also paves the way towards studying NH effects in strongly correlated systems in the lab.

Expertise and Environment

The PI is considered an expert in NH topology, and the host institute offers a vibrant scientific environment. As such, they form the perfect combination for carrying out this highly interdisciplinary research program with the goal to establish a novel perspective on open and correlated quantum systems.