The possibility of low-energy surface plasmon amplification by optically excited excitons in small-diameter single-wall carbon nanotubes is theoretically demonstrated. The nonradiative ...exciton-plasmon energy transfer causes the buildup of macroscopic population numbers of coherent localized surface plasmons associated with high-intensity coherent local fields formed at nanoscale throughout the nanotube surface. These strong local fields can be used in a variety of new optoelectronic applications of carbon nanotubes, including near-field nonlinear-optical probing and sensing, optical switching, enhanced electromagnetic absorption, and materials nanoscale modification.
Deep spiking neural networks are one of the promising eventbased sensor signal processing concepts. However, the practical application of such networks is difficult with standard deep neural network ...training packages. In this paper, we propose a vector-matrix description of a spike neural network that allows us to adapt the traditional backpropagation algorithm for signals represented as spike time sequences. We represent spike sequences as binary vectors. This enables us to derive expressions for the forward propagation of spikes and the corresponding spike training algorithm based on the back propagation of the loss function sensitivities. The capabilities of the proposed vector-matrix model are demonstrated on the problem of handwritten digit recognition on the MNIST data set. The classification accuracy on test data for spiking neural network with 3 hidden layers is equal to 98.14%.
The flutter of an elastic plate in a viscous supersonic gas flow is investigated. The influence of viscous perturbations of the boundary layer on the single-mode flutter is studied considering two ...different types of a boundary layer profile: the generalized convex boundary layer profile and the profile with a generalized inflection point. It is shown that in the case of the convex layer for thick boundary layers the plate is fully stabilized. In the case of a profile with the generalized inflection point, the thickening of the layer first yields the increase of the growth rates of the perturbations, and the growth is greater than in the inviscid approximation. Numerical simulation of two-dimensional supersonic gas flows with boundary layers (that can have a destabilizing effect on the flutter of an elastic surface) over different curved surfaces is performed. The flow patterns over them are studied: regions of these surfaces, over which stable boundary-layer profiles with a generalized inflection point are formed, are found, and their boundaries are obtained.
Abstract
Ever since its inception, coherent excited states of semiconductors have been the focus of semiconductor materials research to evolve into a vibrant field of low-dimensional solid-state ...physics. The field is gaining new momentum these days due to emerging transdimensional semiconductors such as van der Waals bound layers of transition metal dichalcogenides (TMDs) of controlled thickness. Here, we develop the theory of magnetic-field-induced Wigner crystallization for charged interlayer excitons (CIE) discovered recently in TMD heterobilayers. We derive the ratio of the potential interaction energy to the kinetic energy for the many-particle CIE system in the perpendicular magnetostatic field of an arbitrary strength and predict the crystallization effect in the strong field regime. We show that magnetic-field-induced Wigner crystallization and melting of CIEs can be observed in magneto-photoluminescence experiments with TMD bilayers of systematically varied electron-hole doping concentrations. Our results advance the capabilities of this new generation of transdimensional quantum materials.
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