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We explore in the present work the near-field radiative heat transfer between two semi-infinite parallel nonlocal dielectric planes by means of fluctuational electrodynamics. We use a theory for the nonlocal dielectric permittivity function proposed by Halevi and Fuchs. This theory has the advantage to include different models performed in the lite...
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The quantization of systems composed of transmission lines connected to lumped circuits poses significant challenges, arising from the interaction between continuous and discrete degrees of freedom. A widely adopted strategy, based on the pioneering work of Yurke and Denker, entails representing the lumped circuit contributions using Lagrangian den...
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... ## BASIC Pseudocode for Automatic Front-end System Temperature Modulation and RAM Program System Temperature [5] 10 PRINT "System On"; 20 FOR I = 0 to 100 30 IF system temperature <= 70 40 THEN fan = on 50 PRINT "Fan On" 60 INPUT "What is the System Temperature, Operator?", N 70 IF system temperature >= 70 Then fan = off 80 PRINT "Fan Off" 90 IF system temperature = 69 Then system = off 100 PRINT "System Alert Cold, Check Unit" 110 LOOP IF system temperature = 80 Then system = off 120 PRINT "System Alert Hot, Turn Off Unit" 130 INPUT "Operator Type in Last System Temperature", N 140 END ...
... In the extreme nanometersized gaps (d < 10 nm), however, necessity of a nonlocal description arises to obtain nondivergent heat fluxes [13]. Thus, so far, theoretical attempts [14][15][16][17] to explain nonlocality have focused on the gap sizes in the extreme near field. Also, recent experimental studies [18][19][20] reveal inconclusive results for nonlocality. ...
Using transdimensional plasmonic materials (TDPM) within the framework of fluctuational electrodynamics, we demonstrate nonlocality in dielectric response alters near-field heat transfer at gap sizes on the order of hundreds of nanometers. Our theoretical study reveals that, opposite to the local model prediction, propagating waves can transport energy through the TDPM. However, energy transport by polaritons at shorter separations is reduced due to the metallic response of TDPM stronger than that predicted by the local model. Our experiments conducted for a configuration with a silica sphere and a doped silicon plate coated with an ultrathin layer of platinum as the TDPM show good agreement with the nonlocal near-field radiation theory. Our experimental work in conjunction with the nonlocal theory has important implications in thermophotovoltaic energy conversion, thermal management applications with metal coatings, and quantum-optical structures.
... It is also shown that popular approximations for the non-local dielectric response, such as hydrodynamic and single-pole models [17][18][19][20][21][22] , fail to capture the SASE absorption peak and one needs more advanced models that take into account kinetic properties of metallic electrons 8,13,22,23 . This fact is very important for modelling optical properties of conductive media when the non-locality in the dielectric response plays a significant role 24 , e.g. to study propagation of plasmons in nanostructures [25][26][27][28] , near-field radiative heat transfer 29 , thermal and zero-point EM energy and forces on curved metallic boundaries 30 , losses in EM emitters placed near a metallic surface 31 , and propagation of EM waves in plasma 14 . ...
Light scattering spectroscopy is a powerful tool for studying various media, but interpretation of its results requires a detailed knowledge of how media excitations are coupled to electromagnetic waves. In electrically conducting media, an accurate description of propagating electromagnetic waves is a non-trivial problem because of non-local light-matter interactions. Among other consequences, the non-locality gives rise to the anomalous (ASE) and superanomalous (SASE) skin effects. As is well known, ASE is related to an increase in the electromagnetic field absorption in the radio frequency domain. This work demonstrates that the Landau damping underlying SASE gives rise to another absorption peak at optical frequencies. In contrast to ASE, SASE suppresses only the longitudinal field component, and this difference results in the strong polarization dependence of the absorption. The mechanism behind the suppression is generic and is observed also in plasma. Neither SASE, nor the corresponding light absorption increase can be described using popular simplified models for the non-local dielectric response.
... The theory of radiative heat transfer 1-6 predicts a divergence of the heat flux exchanged between two bodies kept at constant temperatures as the separation distance d between them tends to zero. During the last decade, theoretical results [7][8][9][10][11][12] have questioned this divergence and shown that it disappears when a nonlocal optical response 13 of the materials is taken into account. Recently, it has been shown that the divergence of the heat transfer can also be removed at subnanometric separation distances because of the interplay of conductive and radiative heat transfer inside the interacting bodies, which lead to the generation of temperature gradients and in turn to a saturation of the heat flux 14,15 . ...
Radiative heat transfer between two bodies saturates at very short separation distances due to the nonlocal optical response of the materials. In this work, we show that the presence of radiative interactions with a third body or external bath can also induce a saturation of the heat transfer, even at separation distances for which the optical response of the materials is purely local. We demonstrate that this saturation mechanism is a direct consequence of a thermalization process resulting from many-body interactions in the system. This effect could have an important impact in the field of nanoscale thermal management of complex systems and in the interpretation of measured signals in thermal metrology at the nanoscale.
... In the last years, the study of far-field and near-field thermal emission of artificial materials attracted a great deal of attention from researchers due to its high potential for important applications in near-field thermal management [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], energy harvesting [21][22][23][24], and coherent thermal sources [25][26][27][28][29][30][31][32][33][34][35][36][37][38]. In Ref. [25] it was demonstrated that a periodically microstructured surface can emit coherent and linearly polarized thermal emission, that opened the perspec- tive for control of the spectral [31,37,[39][40][41][42], angular [43,44], coherence [25,45], and polarization characteristics [46][47][48][49][50][51][52] of thermal radiation. ...
Thermal radiation from bulk disorderly placed nonresonant emitters is incoherent broadband and isotropic. In an external magnetic field the thermal radiation from any source is circularly polarized. Here we propose a thermal radiation source which emits circularly polarized radiation and which is not placed in a magnetic field. The thermal source consists of a slab waveguide with etched chiral metasurface of fourfold rotational symmetry. Using the Fourier modal method we analyze the eigenmodes of the structure and the emissivity spectra. We demonstrate that due to the absence of a mirror symmetry of the metasurface its eigenmodes as well as the thermally generated electromagnetic waves become circularly polarized. In this paper we discuss the origin of this phenomenon in detail. We demonstrate that the degree of circular polarization in an optimized structure can be as high as 0.87.
... Finally, we take the sources |P (0) m to arise from thermal fluctuations. The fluctuation-dissipation theorem states that for any polarizable body, thermal current fluctuations are related to the dissipative part of the susceptibility via [75], ...
Thermal radiative phenomena can be strongly influenced by the coupling of phonons and long-range electromagnetic fields at infrared frequencies. Typically employed macroscopic descriptions of thermal fluctuations tend to ignore atomistic effects that become relevant at nanometric scales, whereas purely microscopic treatments ignore long-range, geometry-dependent electromagnetic effects. We describe a mesoscopic framework for modeling thermal fluctuation phenomena among molecules in the vicinity of macroscopic bodies, conjoining atomistic treatments of electronic and vibrational fluctuations obtained from ab-initio density functional theory in the former with continuum descriptions of electromagnetic scattering in the latter. The interplay of these effects becomes particularly important at mesoscopic scales, where phonon polaritons can be strongly influenced by the finite sizes, shapes, and non-local/many-body response of the bodies to electromagnetic fluctuations. We show that even in small but especially in elongated low-dimensional molecular systems, such effects can modify thermal emission and heat transfer by orders of magnitude and produce qualitatively different behavior compared to predictions based on local, dipolar, or pairwise approximations valid only in dilute media.
... However, in the spatially local theory the calculated heat transfer rate diverges as soon as the separation of the bodies vanishes, i.e. when d 0. Recent works [16][17][18][19] showed that, in order to overcome these divergences, spatial nonlocality (or spatial dispersion) of the dielectric tensor must be taken into account. In addition, spatial dispersion changes the mode structure of surface plasmons and thus the spectral heat transfer rate. ...
We calculate numerically the heat transfer rate between a spatially dispersive sphere and a half-space. By utilising Huygens' principle and the extinction theorem, we derive the necessary reflection coefficients at the sphere and the plate without the need to resort to additional boundary conditions. We find for small distances $d\sim 1$nm a significant modification of the spectral heat transfer rate due to spatial dispersion. As a consequence, the spurious divergencies that occur in spatially local approach are absent.
... If the separation is too small compared to the thermal wavelength, then energy transfer exceeds the well-known classical Planck's law of the black-body radiation 1 . Several studies have shown that the radiative heat transfer between objects with planar geometry depends on the materials and could be manipulated by using anisotropic materials, layered materials, and covering objects with different material composition [2][3][4][5][6][7] . In addition to the separation distance, the radiative heat transfer in a dimer of nanoparticles depends on various properties of the constituent nanoparticles, including material composition 8,9 , size 10 , surface structure 11 , shape [12][13][14] , and relative orientation [15][16][17] . ...
... System consists of two identical core-shell nanoparticles with separation d. Each nanoparticle characterized by its core radius Rin, outer radius Rout, shell thickness t = Rout − Rin, core volume fraction f = (Rin/Rout) 3 , permittivity of the inner layer ǫc, and permittivity of the outer layer ǫs. ...
Radiative heat transfer in systems with core-shell nanoparticles may exhibit not only a combination of disparate physical properties of its components but also further enhanced properties that arise from the synergistic properties of the core and shell components. We study the thermal conductance between two core-shell nanoparticles (CSNPs). We predict that the radiative heat transfer in a dimer of Au@SiO$_2$ CSNPs (i.e., silica-coated gold nanoparticles) could be enhanced several order of magnitude compared to bare Au nanoparticles. However, the reduction of several order of magnitude in the heat transfer is possible between SiO$_2$@Au CSNPs (i.e., silica as a core and gold as a shell) than that of uncoated SiO$_2$ nanoparticles.
... These surprising results question the validity of current theories of heat transfer for these small gaps. Researchers have explored the possibility of reconciling the experimental data with computations, by relaxing the local approximation 21 that is often employed in calculations of near-field radiative heat transfer; however, such investigations 34,35 suggest that the inclusion of nonlocal effects leads to relatively modest changes of heat fluxes in the extreme near-field (down to gap sizes of a few Å). The contribution of phonons to thermal transport across vacuum gaps has also been investigated [36][37][38][39][40] . ...
Radiative heat transfer in Ångström-and nanometre-sized gaps is of great interest because of both its technological importance and open questions regarding the physics of energy transfer in this regime. Here we report studies of radiative heat transfer in few Å to 5 nm gap sizes, performed under ultrahigh vacuum conditions between a Au-coated probe featuring embedded nanoscale thermocouples and a heated planar Au substrate that were both subjected to various surface-cleaning procedures. By drawing on the apparent tunnelling barrier height as a signature of cleanliness, we found that upon systematically cleaning via a plasma or locally pushing the tip into the substrate by a few nanometres, the observed radiative conductances decreased from unexpectedly large values to extremely small ones—below the detection limit of our probe—as expected from our computational results. Our results show that it is possible to avoid the confounding effects of surface contamination and systematically study thermal radiation in Ångström-and nanometre-sized gaps.
... On the other hand, the minimum gap distance of the FDM is determined by the valid regime of fluctuational electrodynamics. Previous studies have revealed that fluctuational electrodynamics may not be sufficient to describe near-field thermal interactions if the separation gap becomes of the order or smaller than the lattice constant of a material [46], for which nonlocal effects of the dielectric function [47,48] as well as quantum electronic coupling effects [49] should be considered. The upper limit of the FDM is H/R ≈ 4, above which the induced charge inside the tip becomes more uniformly distributed and thus cannot be approximated with a point charge, Q i . ...
Fig. 1. Schematic of a tip with radius R and temperature Tt a distance H above a surface at temperature Ts as modeled by (a) the PDM, (b) the FDM with no surface, and (c) the FDM near the surface. The FDM uses a prolate spheroidal geometry with semi-major axis Lp. The non-perturbed charge distributions, Qo and , are formed by incident electric field without the surface while the induced charge distributions, Qi and , are induced by the near-field interaction between the tip and surface quantified by and .
