Moladad Nikbakht

Various unusual behavior of artificial materials is governed by their topological properties, among these, the edge state in classical and quantum wave systems has captured significant attention due to its widespread relevance and applications across various fields of study. Observation of such topological features has led researchers to extend the idea of band theory to diffusive systems. Inspired by the well-known Su-Schriefer-Heegar (SSH) model we employed the concept of band topology to explore the topological characteristics of radiative heat transfer in a one-dimensional chain consisting of an odd number of nanoparticles. We demonstrate the topological phase transition, and topological modes with edge as well as bulk states in an array of nanoparticles exchanging heat via radiation. The demonstrated topological features of radiative systems can find important applications in the future studies of heat transfer at the nanoscale.

Recent advancements in the field of topological band theory have significantly contributed to our understanding of intriguing topological phenomena observed in various classical and quantum systems, encompassing both wave and dissipative systems. In this study, we employ the notion of band theory to establish a profound connection between the spatiotemporal evolution of temperatures and the underlying topological properties of radiative systems. These systems involve the exchange of energy through radiation among a collection of particles. By utilizing the eigenstates of the response matrix of the system, we establish a robust framework for the examination of topological properties in radiative systems, considering both symmetric and asymmetric response matrices. Our formalism is specifically applied to investigate the topological phase transition in a one-dimensional chain composed of an even number of spherical nanoparticles. We provide compelling evidence for the existence and robustness of topological edge states in systems characterized by an asymmetric response matrix. Moreover, we demonstrate that by manipulating the arrangement and volume of particles, it is possible to control the system's structure and achieve desired topological features. Interestingly, we showed that the radiative heat transfer can be controlled and prevented by topological insulation. Additionally, we conduct an analysis of the temperature dynamics and the associated relaxation process in the proposed system. Our research findings demonstrate that the interplay between bulk states and localized states is pivotal in the emergence of distinct eigenstates and provides significant insights into the spatiotemporal dynamics of temperature and the process of thermalization within a system. This interplay holds the potential to be leveraged for the development of structures, facilitating efficient heat transfer even in the presence of perturbation. Consequently, it enables precise experimental measurements of heat transfer and serves as a platform for the exploration of thermal topology, offering new avenues for scientific inquiry in this field.

Recent advancements in the field of topological band theory have significantly contributed to our understanding of intriguing topological phenomena observed in various classical and quantum systems, encompassing both wave and dissipative systems. In this study, we employ the notion of band theory to establish a profound connection between the spatio-temporal evolution of temperatures and the underlying topological properties of radiative systems. These systems involve the exchange of energy through radiation among a collection of particles. By utilizing the eigenstates of the response matrix of the system, we establish a robust framework for the examination of topological properties in radiative systems, considering both symmetric and asymmetric response matrices. Our formalism is specifically applied to investigate the topological phase transition in a one-dimensional chain composed of an even number of spherical nanoparticles. We provide compelling evidence for the existence and robustness of topological edge states in systems characterized by an asymmetric response matrix. Moreover, we demonstrate that by manipulating the arrangement and volume of particles, it is possible to control the system's structure and achieve desired topological features. Interestingly, we showed that the radiative heat transfer can be controlled and prevented by topological insulation. Additionally, we conduct an analysis of the temperature dynamics and the associated relaxation process in the proposed system. Our research findings demonstrate that the interplay between bulk states and localized states is pivotal in the emergence of distinct eigenstates and provides significant insights into the spatio-temporal dynamics of temperature and the process of thermalization within a system.

Radiative thermal diodes based on two-element structures rectify heat flows thanks to a temperature dependence of material optical properties. The heat transport asymmetry through these systems, however, remains weak without a significant change in material properties with the temperature. Here we explore the heat transport in three-element radiative systems and demonstrate that a strong asymmetry in the thermal conductance can appear because of many-body interactions, without any dependence of optical properties on the temperature. The analysis of transport in three-body systems made with polar dielectrics and metallic layers reveals that rectification coefficients exceeding 50 % can be achieved in the near-field regime with temperature differences of about 200 K. This work paves the way for compact devices to rectify near field radiative heat fluxes over a broad temperature range and could have important applications in the domain of nanoscale thermal management.

Radiative thermal diodes based on two-element structures rectify heat flows thanks to a temperature dependence of material optical properties. The heat transport asymmetry through these systems, however, remains weak without a significant change in material properties with the temperature. Here we explore the heat transport in three-element radiative systems and demonstrate that a strong asymmetry in the thermal conductance can appear because of many-body interactions, without any dependence of optical properties on the temperature. The analysis of transport in three-body systems made with polar dielectrics and metallic layers reveals that rectification coefficients exceeding 50% can be achieved in the near-field regime with temperature differences of about 200 K. This work paves the way for compact devices to rectify near-field radiative heat fluxes over a broad temperature range and could have important applications in the domain of nanoscale thermal management.

A theory of temperature dynamics in many-body systems driven by time-dependent external sources is introduced. The formalism is based on the combination of perturbation theory and the fluctuational-electrodynamics approach in many-body systems. By using response theory, an explicit formula for temperature and phase shifts is derived and expressed in terms of the amplitude and phase of external power sources. Although the proposed method is highly efficient because it can skip the transient response, it is valid when external powers are weak. As an illustration of this theoretical framework, we have shown the dynamics of temperatures in one, two, and three degrees of freedom systems driven by sine wave input powers. Finally, we highlight some emergent phenomena arising from purely dynamical many-body effects, including amplification, attenuation, delaying, or accelerating temperature responses. This work could find important applications in the domain of dynamical thermal management at the nanoscale.

In the present article the radiative thermal current and radiative resistance are introduced and investigated in a system of parallel slabs. The system is placed in an environment with a constant temperature and subjected to a constant temperature gradient, which causes a radiative energy flux through the system. We have calculated the steady-state temperature profile of the system, assuming that the material and thickness of the middle slab could be different from the other slabs. We propose the exact formulation for calculating the thermal current and thermal resistances in both linear and nonlinear regimes. According to our results, the middle slab acts as a thermal barrier, and depending on the width of this barrier, an extreme thermal isolation is achievable. Simulation results indicate that the thermal resistance of the barrier is an increasing function of the thickness for near-field separation distances but is virtually insensitive to the barrier width in the far-field regime. The long-range character of the radiative heat transfer which occurs in systems with identical slabs is also discussed.

In present article the radiative thermal current and radiative resistance are introduced and investigated in a system of parallel slabs. The system is placed in an environment with a constant temperature and subjected to a constant temperature gradient, which causes a radiative energy flux through the system. We have calculated the steady-state temperatures profile of the system, assuming that the material and thickness of the middle slab could be different from the other slabs. We propose the exact formulation for calculating the thermal current and thermal resistances in both linear and nonlinear regimes. According to our results, the middle slab acts as a thermal barrier and depending on the width of this barrier, an extreme thermal isolation is achievable. Simulation results indicate that the thermal resistance of the barrier is an increasing function of the thickness for near-field separation distances but it is virtually insensitive to the barrier width in far field regime. The long range character of the radiative heat transfer, which occurs in system with identical slabs is also discussed.