In the first part of my talk I discuss the prediction and physical consequences of a new geometric zero-th order critical transition occurring to the Casimir torque at Theta=0 rotation angle between diffraction gratings. In the second part I discuss the theory predictions and proposal for the realization of a genuinely quantum thermal machine to be realized in systems out of thermal equilibrium. Here the recorded video: "https://online.kitp.ucsb.edu/online/flectro22/antezza/".

This is a broad-audience public lecture names "KITP Blackboard Lunch" I gave at the Kavli Institute of Theoreical Physics (KITP) at the University of California at Santa Barbara (UCSB) to discuss the physical basis of the core subjects of the KITP 7-week program "Emerging Regimes and Implications of Quantum and Thermal Fluctuational Electrodynamics" I organized at KITP. This lecture was devoted to the KITP permanent staff and to all the participants to the several KITP programs. Here the recorded video: "https://online.kitp.ucsb.edu/online/bblunch/antezza"

After a rapid introduction to the basic physical concepts of radiative heat transfer, I will focus on the study of the radiative heat transfer between two identical metallic one-dimensional lamellar gratings. To this aim I will present and exploit a modification to the widely used Fourier modal method, known as adaptive spatial resolution, based on a stretch of the coordinate associated with the periodicity of the grating. I show that this technique dramatically improves the rate of convergence when calculating the heat flux, and that there is a remarkable amplification of the exchanged energy, ascribed to the appearance of spoof-plasmon modes. By comparing our results to recent studies, we find a consistent quantitative disagreement with some previously obtained results going up to 50%.

Excitation of hybrid modes constituted by different material-supported polaritons is a common way to enhance the near-field radiative energy transport, which has fascinating promise in applications of thermal photonics. Here, we investigate near–field thermal radiation mechanisms in heterostructure composed of hBN film and black phosphorus single layer. The results show that this heterostructured system can give rise to a remarkable enhancement for photon tunneling, outperforming the near-field thermal radiation properties of its building blocks, as well as some other representative heterostructures. Moreover, we find that the anisotropic hybrid effect can induce a remarkable topological reconstitution of polaritons for hBN film and black phosphorus, forming a novel anisotropic hybrid polaritons. Notably, such hybrid modes show significant topological differences compared to hBN film and black phosphorus in the type-I Reststrahlen band due to the anisotropic anticrossing hybridization effect. Lastly, we systematically analyze the evolution of such hybrid polariton modes as a function of hBN film thickness and the corresponding influence on radiative properties of the heterostructure. This work may benefit the applications of near-field energy harvesting and radiative cooling based on hybrid polaritons in anisotropic two-dimensional material and hyperbolic film.

InGaN/GaN single quantum wells were grown by molecular beam epitaxy on the silicon substrate onto thin AlN and GaN buffer layers. The InGaN/GaN structure is porosified using a combination of SixNy nanomasking and sublimation and compared with a non-porous reference. The photoluminescence efficiency at room temperature of the porosified sample is improved by a factor reaching 40 compared with the reference sample. Plan-view and cross-sectional transmission electron microscopy images reveal that the remaining material is free of dislocation cores. The regions around dislocations are, thus, preferentially sublimated. This explains the strong photoluminescence improvement of nanoporous InGaN/GaN samples.

In this work we investigate the properties of negatively charged nitrogen-vacancy (NV−) centres created during single crystal diamond growth by chemical vapour deposition (CVD) on [113]-oriented substrates and with N2O as a dopant gas. The use of spin echo and double electron-electron resonance (DEER) allows us to assess NV− ratio with respect to substitutional nitrogen impurities (N_S0) incorporated during growth, a critical figure of merit for quantum technologies. We demonstrate that, at moderate growth temperatures (800 °C), dense NV− ensembles of several hundreds of ppb (800 ppb for 50 ppm of added N2O) and with exceptionally high NV−/N_S0 ratios of up to 25% can be achieved. This NV− creation yield is higher by at least an order of magnitude to that typically obtained on standard [100]-grown diamonds and comparable to the best values reported for electron-irradiated diamonds. The material obtained here thus advantageously combines a high NV− density, high creation yield, long coherence times of several tens of μs together with a partial preferential orientation. These are highly desirable requirements for diamond-based quantum sensors that may spur new developments with this crystalline orientation leading to improved performance and sensitivity.