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Cold atoms in an optical lattice provide an ideal platform for studying Bloch oscillations. Here, we extend Bloch oscillations to two superposed optical lattices that are accelerated away from one another, and for the first time show that…
Special localized wavemodes show up in several physical scenarios including BEC in optical lattices, nonlinear photonic crystals and systems with strong electron-phonon interaction. These result from an underlying nonlinear contribution to…
Embedded Si and Ge nanocrystals (NCs) in wide band-gap matrices are studied theoretically using an atomistic pseudopotential approach. From small clusters to large NCs containing on the order of several thousand atoms are considered.…
The ac Stark effect can shift initially nonresonant minibands in semiconductor superlattices into multiphoton resonances. This effect can result in strongly enhanced generation of a particular desired harmonic of the driving laser…
The effects of chemical disorder on the electronic and optical properties of semiconductor alloy multilayers are studied based on the tight-binding theory and single-site coherent potential approximation. Due to the quantum confinement of…
The phenomenological boundary conditions for the envelope wave function, which is applicable for contacts of semiconductors with the rather different crystal symmetry are proposed. It is shown that the boundary conditions are determined by…
Generalized with respect to the Stark interaction of atoms with a vacuum field of zero photon density, Dicke's model is used to describe the Raman superradiance of a localized ensemble of identical atoms in a coherent non-resonant light…
We consider terahertz absorption and gain in a single miniband of semiconductor superlattice subject to a bichromatic electric field in the most general case of commensurate frequencies of the probe and pump fields. Using an exact solution…
Surface-state mediated interactions between adsorbates on surfaces can be exploited for the fabrication of self-organized nanostructures such as two-dimensional superlattices of adatoms. Using angle-resolved photoemission we provide…
We present a theoretical approach to calculate the {\it local} absorption spectrum of excitons confined in a semiconductor nanostructure. Using the density-matrix formalism, we derive a microscopic expression for the non-local…
The infrared range optical absorption mechanism of Carbon-Copper composite thin layer coated on the Diamond-Like Carbon (DLC) buffer layer has been investigated. By consideration of weak interactions between copper nanoparticles in their…
We address the issue of inter-particle dipolar interactions in the context of magnetic hyperthermia. More precisely, the main question dealt with here is concerned with the conditions under which the specific absorption rate is enhanced or…
We examine phenomenon of electromagnetic transparency in semiconductor superlattices (having various miniband dispersion laws) in the presence of multi-frequency periodic and non-periodic electric fields. Effects of induced transparency and…
The mixed-state resistive response of a superconductor thin film with an asymmetric washboard pinning potential subject to superimposed dc and ac currents of arbitrary amplitudes and frequency at finite temperature is theoretically…
The electromagnetic response of Dirac semimetals in the infrared and terahertz frequency ranges is attracting growing interest for potential applications in optoelectronics and nonlinear optics. The interplay between the free-carrier…
The problem of the one-exciton absorption spectrum is considered for the lattice of two-level interacting atoms whose initial energy splitting depends on the coordinate. It is shown that for some types of interatomic interaction, this…
A theory of the frequency dependence of the interplane conductivity of a strongly anisotropic superconductor is presented. The form of the conductivity is shown to be a sensitive probe of the strength of quantum and thermal fluctuations of…
Linear and nonlinear optical absorption coefficients of the two-dimensional semiconductor ring in the perpendicular magnetic field $\bf B$ are calculated within independent electron approximation. Characteristic feature of the energy…
In this paper we investigate the effect of Cd doping at ultra-low concentrations in SnO$_2$ both experimentally, by measuring the temperature dependence of the electric quadrupole hyperfine interactions with time-differential perturbed…
The four-wave mixing produced with two ultrashort phase-locked w-3w laser pulses propagating coherently in a two-level system in the infrared spectral region is shown to depend on the pulses relative phase. The Maxwell-Bloch equations are…