Non-Hermitian physics and topological phenomena in convective thermal metamaterials

TL;DR

This paper reviews recent advances in non-Hermitian physics and topological phenomena in convective thermal metamaterials, highlighting their implementation, unique phases, and potential industrial applications.

Contribution

It provides a comprehensive overview of how convection enables realization of non-Hermitian and topological phases in thermal metamaterials, expanding beyond conduction-only systems.

Findings

Implementation of exceptional points in thermal diffusion

Observation of chiral thermal behavior near exceptional points

Identification of Weyl exceptional rings in convective systems

Abstract

Non-Hermitian physics and topological phenomena are two hot topics attracted much attention in condensed matter physics and artificial metamaterials. Thermal metamaterials are one type of metamaterials that can manipulate heat on one's own. Recently, it has been found that non-Hermitian physics and topological phenomena can be implemented in purely diffusive systems. However, conduction alone is not omnipotent due to the missing of degrees of freedom. Heat convection, accompanying with conduction, is capable of realizing a large number of phases. In this review, we will present some important works on non-Hermitian and topological convective thermal metamaterials. In non-Hermitian physics, we will first discuss the implementation of exceptional point (EP) in thermal diffusion, followed by high-order EP and dynamic encirclement of EP. We then discuss two works on the extensions of EP in diffusion systems, namely, the chiral thermal behavior in the vicinity of EP and the Weyl exceptional ring. For topological phases, we will discuss two examples: a one-dimensional topological insulator and a two-dimensional quadrupole topological insulator. Finally, we will make a conclusion and present a promising outlook in this area. Besides the scientific values, non-Hermitian and topological convective thermal metamaterials have great potentials for industrial applications.