Diffusive skin effect and topological heat funneling

Abstract

Non-Hermitian wave system has attracted intense attentions in the past decade since it reveals interesting physics and generates various counterintuitive effects. However, in the diffusive system that is inherently non-Hermitian with natural dissipation, the robust control of heat flow is hitherto still a challenge. Here we introduce the skin effect into diffusive systems. Different from the skin effect in wave systems, where asymmetric couplings were enabled by dynamic modulations or judicious gain/loss engineering, asymmetric couplings of the temperature fields in diffusive systems can be realized by directly contacted metamaterial channels. Topological heat funneling is further presented, where the temperature field automatically concentrates towards a designated position and shows a strong immunity against the defects. Our work indicates that the diffusive system can provide a distinctive platform for exploring non-Hermitian physics as well as thermal topology.

Diffusive Skin Effect in Zeolites

“…In this work, we took methane as an instance and focused on the diffusion trajectory inside various zeolites. Similar to the density of current in the skin part of conductor, − we found an intriguing “skin effect” during the diffusion process in more than 200 kinds of zeolites, where methane molecules preferentially diffused along the wall of zeolites regardless of the pore channels.…”

Introduction

“…The third level (LV3) is other theories for designing functions not predicted by the transformation theory. With the development of theoretical thermotics, many phenomena and functions beyond the predictions of transformation thermotics were revealed, such as the anti-parity-time symmetry in diffusive systems [21,22], diffusive geometric phases [23,24], thermal wave nonreciprocity [25][26][27][28][29], thermal edge states [30][31][32][33][34], and thermal skin effects [35,36]. These emerging theories may guide the future development of theoretical thermotics.…”

Two-Dimensional Thermal Regulation Based on Non-Hermitian Skin Effect

“…[29] As a result, non-Hermitian physics phenomena [30,31] such as non-Hermitian skin effect (NHSE) [32][33][34][35][36][37] can also be applied in designs of thermal regulation systems. [38] In this Letter, we present a combination of thermal diffusion coupled mode theory and NHSE. We propose two models: a two-dimensional edge state Su-Schrieffer-Heeger (SSH) model and a two-dimensional corner state SSH model.…”