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With examples and clear explanation throughout, this step-by-step approach makes quantum theory of plasmons accessible to readers without specialized training in theory. Jacak uses original research results to offer a fully analytical theory formulation suitable for further development and applications. The theory is focused on the Random Phase Approximation description of plasmons in metallic nano-structures, previously defined for bulk metal. Particular attention is paid to large damping of plasmons in nanostructures including electron scattering and Lorentz friction losses, quantum description of plasmon photovoltaic effect is presented and there is in-depth analysis of plasmon-polariton kinetics in metallic nano-chains. Suitable for students in the field of plasmonics, opto-electronics and photonics, and for researchers active in the field of photo-voltaics, opto-electronics, nano-plasmonics and nano-photonics. Also of help to researchers in soft plasmonics with applications to electro-signalling in neurons.

The challenging question on possible plasmon type excitations in finite ionic systems is discussed. The related theoretical model is formulated and developed in order to describe surface and volume plasmons of ion liquid in finite electrolyte systems. The irradiation of ionic surface plasmon fluctuations is studied in terms of the Lorentz friction of oscillating charges. The attenuation of surface plasmons in the ionic sphere is calculated and minimized with respect to the sphere size. Various regimes of approximation for description of size effect for damping of ionic plasmons are determined and a cross-over in damping size-dependence is demonstrated. The most convenient dimension of finite electrolyte system for energy and information transfer by usage of ionic dipole plasmons is determined. The overall shift of size effect to micrometer scale for ions in comparison to nanometer scale for electrons in metals is found and by several orders red shift of plasmonic resonances in ion systems is predicted in a wide range of variation depending of ion system parameters. This convenient opportunity of tuning of resonances differs ionic plasmons from plasmons in metals where electron concentration was firmly fixed.

We propose a new model of the saltatory conduction in myelinated axons. This conduction of the action potential in myelinated axons does not agree with the conventional cable theory, though the latter has satisfactorily explained the electrosignaling in dendrites and in unmyelinated axons. By the development of the wave-type concept of ionic plasmon-polariton kinetics in axon cytosol we have achieved an agreement of the model with observed properties of the saltatory conduction. Some resulting consequences of the different electricity model in the white and the gray matter for nervous system organization have been also outlined.SIGNIFICANCEMost of axons in peripheral nervous system and in white matter of brain and spinal cord are myelinated with the action potential kinetics speed two orders greater than in dendrites and in unmyelinated axons. A decrease of the saltatory conduction velocity by only 10% ceases body functioning. Conventional cable theory, useful for dendrites and unmyelinated axon, does not explain the saltatory conduction (discrepancy between the speed assessed and the observed one is of one order of the magnitude). We propose a new nonlocal collective mechanism of ion density oscillations synchronized in the chain of myelinated segments of plasmon-polariton type, which is consistent with observations. This model explains the role of the myelin in other way than was previously thought.

We demonstrate a new wave-type model of saltatory conduction in myelinated axons. A poor conductivity of the neuron cytosol limits electrical current signal velocity upon the cable theory, to 1–3 m/s, whereas the saltatory conduction undergoes with the velocity of signal transduction 100–300 m/s. We propose the wave-type mechanism of the saltatory conduction in the form of kinetics of ion plasmon-polariton being the hybrid of the electromagnetic wave and of the ion plasma oscillations, which meets the observations. Plasmons oscillations have a quantum character to some extent as the coherent oscillations of all ions are possible due to their repulsion which can be understood upon the quantum approach like random phase approximation by Pines and Bohm. Basing on the difference of electricity of myelinated white matter and nonmyelinated gray matter in cortex we outline the topological concept of the memory functioning.

Photovoltaics is amongst the most important technologies for renewable energy sources, and plays a key role in the development of a society with a smaller environmental footprint. Key parameters for solar cells are their energy conversion efficiency, their operating lifetime, and the cost of the energy obtained from a photovoltaic system compared to other sources. The optimization of these aspects involves the exploitation of new materials and development of novel solar cell concepts and designs. Both theoretical modeling and characterization of such devices require a comprehensive view including all scales from the atomic to the macroscopic and industrial scale. The different length scales of the electronic and optical degrees of freedoms specifically lead to an intrinsic need for multiscale simulation, which is accentuated in many advanced photovoltaics concepts including nanostructured regions. Therefore, multiscale modeling has found particular interest in the photovoltaics community, as a tool to advance the field beyond its current limits. In this article, we review the field of multiscale techniques applied to photovoltaics, and we discuss opportunities and remaining challenges. © T. Abu Hamed et al., published by EDP Sciences, 2018., European Cooperation in Science and Technology: MP1406, The authors are grateful for the financial support by the COST Action MP1406 “MultiscaleSolar.”

We analyze theoretically a hybridization type dressing of orbital (i.e., charge) and spin degrees of freedom of excitations captured in semiconductor quantum dot with band phonons and magnons (the latter for magnetic semiconductor surroundings), as a mechanism of dephasing of rapidly excited dot exciton state. Within the Green function approach we derive our previously formulated heuristic general rule for estimation of corresponding dephasing time-rate. The pure dephasing (off-diagonal decoherence) of quantum dot exciton resulting due to this dressing is studied, for both orbital and spin states of the exciton. A significant difference between phonon-induced (for charge) and magnon-assisted (for spin) quantum dot exciton dephasing is indicated as the result of the spin conservation, which leads to the disappearance of the exciton spin pure-dephasing at T = 0 (freezing out of spin dephasing), in contrary to the exciton charge dephasing caused by phonons, which maintains strong even at T = 0.

We demonstrate disappearance at 0 T = 0, and strong reduction at low temperatures, of pure-dephasing of exciton spin located in a quantum dot (QD) embedded in a magnetic medium, e.g. in a diluted magnetic semiconductor. The off-diagonal spin decoherence results due to hybridization of local QD exciton spin with magnons from surrounding crystal–we estimate the corresponding time-scale and formulate a general rule for the scaling of dephasing time versus QD diameter derived within the Green function approach (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A lasing system based on electrically driven quantum dot matrix is proposed, where population inversion of the dot matrix is obtained by rapid (nonadiabatic) switching on of in-plane electric field as a pumping force. Numerical analysis of electron-photon system kinetics is performed for various electric fields and temperatures. For parabolic type of confinement in QDs, a convenient amplification of contribution from several levels is indicated. The relevant analysis utilises an exact solution of Cauchy problem for an infinite chain of linear differential equations.

The growing interest is recently focusing on QDs of type II, which contrary to type I QDs attract electrons and repulse holes (or conversely). In such QDs an electron-hole pair (Xexciton) can still be traped due to electron-hole Coulomb attraction, resulting in significantly more complex structure of excitonic states. We consider an X exciton in QD of type II defined by electrostatic focusing in a narrow quantum well, in the presence of additional external in-plane electric field. The dependence of PL spectrum on dot size and in-plane electric field is analysed within the Hartree approach for model planar Gaussian confinement. The exciton ground state and its energy red-shift are found as a function of electric field and dot size. Corresponding rearrangement of PL spectrum is described.

Phonon-induced decoherence of orbital degrees of freedom in quantum dots (QDs) (GaAs/InAs) is studied and the relevant time-scales are estimated versus dot dimension. Dephasing of excitons due to acoustic phonons and optical phonons, including enhancement of the effective Frohlich constant caused by localization, is assessed for the state-of-art QDs. Temporal inefficiency of Pauli blocking in QDs due to lattice inertia is additionally predicted. For QD placed in a diluted magnetic semiconductor medium a magnon induced dephasing of spin is estimated in accordance with experimental results for Zn(Mn)Se/CdSe. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Recent experimental investigations of far-infrared attenuation in GaAs/InAs quantum dot in magnetic field and measurements of photoluminescence features for smaller pyramid-shape GaAs/InAs quantum dots indicated an enhancement of coupling of longitudinal optical phonons with confined electrons, which manifested itself in a significant increase of the effective Frohlich constant in comparison to its bulk value. We give a simple quasiclassical explanation of this enhancement and relate the renormalization of the Frohlich constant with the dot diameter.

Surface plasmons in metallic nanostructures including metallically nanomodified solar cells are conventionally studied and modeled by application of the Mie approach to plasmons or by the finite element solution of differential Maxwell equations with imposed boundary and material constraints (e.g., upon commercial COMSOL software system). Both approaches are essentially classical ones and neglect quantum particularities related to plasmon excitations in metallic components. We demonstrate that these quantum plasmon effects are of crucial importance especially in theoretical simulations of plasmon-aided photovoltaic phenomena. Quantum corrections considerably improve both the Mie and COMSOL approaches in this case. We present the semiclassical random phase approximation description of plasmons in metallic nanoparticles and apply the quantumFermi golden rule scheme to assess the sunlight energy transfer to the semiconductor solar cell mediated by surface plasmons in metallic nanoparticles deposited on the top of the battery. In addition, short-ranged electron-electron interaction in metals is discussed in the framework of the semiclassical hydrodynamic model. The significance of the related quantum corrections is illustrated by the quantumly improved COMSOL simulations. (C) 2017 Optical Society of America

In equidistant infinite chain of metallic nanospheres the collective mode of surface plasmons propagates without radiative losses, i.e., the Lorentz friction losses in each nanosphere are compensated by energy income in near-, medium- and far-field from the rest of the chain. Within an approximate approach including numerical studies in Green function framework it has been indicated superluminal propagation of some plasmon-polariton modes. By the exact solution of the nonlinear dynamic equation we demonstrate that the superluminal modes were an artifact of the perturbation solution type and we show that the group velocities for both polarizations are limited by light velocity, though vary in large range depending on chain parameters and are typically one order lower than the light velocity.

The spin degrees of freedom in quantum dots (QDs) of He‐type embedded in diluted magnetic semiconductor (DMS) medium are considered for modelling of qubit and gate for quantum information processing (QIP). The qubit is defined as a singlet and triplet pair of states of two electrons in He QD. Methods of qubit rotations and two‐qubit operations are considered. Decoherence due to spin waves in magnetically ordered phase of DMS is however recognized as the the source of unavoidable dephasing with inconvenient, from point of view of the DiVincenzo conditions, time‐scale.

Phonon-induced unavoidable decoherence of orbital degrees of freedom in quantum dots is studied and the relevant time scales are estimated. Dephasing of excitons due to acoustic phonons and, in a polar medium, to optical phonons, including anharmonic effects and enhancement of the effective Fr\"ohlich constant due to localization, is assessed for typical self-assembled quantum dots. Temporal inefficiency of Pauli blocking due to lattice inertia is predicted. For quantum dots placed in a diluted magnetic semiconductor medium a magnon-induced dephasing of a spin is also estimated in accordance with experimental results.

The random-phase-approximation semiclassical scheme for description of plasmon excitations in large metallic nanospheres (with radius 10--100 nm) is developed for a case of presence of dynamical electric field. The spectrum of plasmons in metallic nanosphere is determined including both surface and volume type excitations and their mutual connections. It is demonstrated that only surface plasmons of dipole type can be excited by a homogeneous dynamical electric field. The Lorentz friction due to irradiation of e-m energy by plasmon oscillations is analysed with respect to the sphere dimension. The resulting shift of resonance frequency due to plasmon damping is compared with experimental data for various sphere radii. Collective of wave-type oscillations of surface plasmons in long chains of metallic spheres are described. The undamped region of propagation of plasmon waves along the chain is found in agreement with some previous numerical simulations.

Semiconductor quantum dots which trap simultaneously electrons and holes are called quantum dots of type-I. Contrary to these structures, empty dots of type-II attract only one type of charged carriers and repel the other. Particularities of confining potential are unaccessible by any direct measurements, thus recognition of quantum dot type by indirect method is highly desired. Our proposal is to distinguish between the two types of quantum dots via a comparison of photoluminescence spectra of these structures, which differ in both cases qualitatively.

In this paper we present results of calculations for quantum dots matrix acting as an active medium in novelty proposal of far-infrared laser. The proposal is based on the pumping laser by rapid (nonadiabatic) switching on in-plane electric field which allows us to obtain population inversion. The numerical analysis of electron-photon system kinetics was performed for various electric fields and temperatures. These calculation utilises the method of solving the Cauchy problem for infinite chain of linear differential equations. Also the contribution of dynamics of non-radiative transitions mediated by the phonons has been taken account. The obtained results indicate that by the properly chosen of QDs parameters it is possible to reduce the rate of these transitions in the degree that allows us to obtain good laser efficiency at low temperatures.