arXiv subjects

K. B. Arnardottir

Publications and source records attributed to K. B. Arnardottir.

4 recordsLinked to original sources

arXiv2018

Terahertz cascades from nanoparticles

In this article we propose a system capable of THz radiation with quantum yield above unity. The system consists of nanoparticles where the material composition varies along the radial direction of each nanoparticle in such a way that a ladder of equidistant energy levels emerges. By then exciting the highest level of this ladder we produce multiple photons of the same frequency in the THz range. We demonstrate how we can calculate a continuous material composition profile that achieves a high quantum yield and then show that a more experimentally friendly design of a multishell nanoparticle can still result in a high quantum yield.

cond-mat.mes-hall↗

arXiv2014

Band gaps induced by vacuum photons in closed semiconductor cavities

We consider theoretically a closed (zero-dimensional) semiconductor microcavity where confined vacuum photonic mode is coupled to electrons in valence band of the semiconductor. It is shown that vacuum-induced virtual electron transitions between valence and conduction bands result in renormalization of electron energy spectrum. As a consequence, vacuum-induced band gaps appear within the valence band. Calculated values of the band gaps are of sub-meV scale, that makes this QED effect to be measurable in state-of-the-art experiments.

cond-mat.mes-hall↗

arXiv2013

One-dimensional Van Hove polaritons

We study the light-matter coupling of microcavity photons and an interband transition in a one-dimensional (1D) nanowire. Due to the Van Hove singularity in the density of states, resulting in a resonant character of the absorption line, the achievement of strong coupling becomes possible even without the formation of a bound state of an electron and a hole. The calculated absorption in the system and corresponding energy spectrum reveal anticrossing behavior characteristic of the formation of polariton modes. In contrast to the case of conventional exciton polaritons, the formation of 1D Van Hove polaritons will not be restricted to low temperatures and can be realized in any system with a singularity in the density of states.

cond-mat.mes-hall↗

arXiv2013

Hall effect for indirect excitons in an inhomogeneous magnetic field

We study the effect of non-homogeneous out-of-plane magnetic field on the behaviour of 2D spatially indirect excitons. Due to the difference of magnetic field acting on electrons and holes the total Lorentz force affecting the center of mass motion of an indirect exciton appears. Consequently, an indirect exciton acquires an effective charge proportional to the gradient of the magnetic field. The appearance of the Lorentz force causes the Hall effect for neutral bosons which can be detected by measurement of the spatially inhomogeneous blueshift of the photoluminescence using counter-flow experiment.

cond-mat.mes-hall↗