Anderson localization as position-dependent diffusion in disordered waveguides

We show that the recently developed self-consistent theory of Anderson localization with a position-dependent diffusion coefficient is in quantitative agreement with the supersymmetry approach up to terms of the order of $1/g_0^2$ (with $g_0$ the dimensionless conductance in the absence of interference effects) and with large-scale {\it ab-initio} simulations of the classical wave transport in disordered waveguides, at least for $g_0 \gtrsim 0.5$. In the latter case, agreement is found even in the presence of absorption. Our numerical results confirm that in open disordered media, the onset of Anderson localization can be viewed as position-dependent diffusion.Comment: 6 pages, 3 figure

Stokes parameters for light scattering from a Faraday-active sphere

We present an exact calculation for the scattering of light from a single sphere made of Faraday-active material, to first order in the external magnetic field. We use a recent expression for the T-matrix of a Mie scatterer in a magnetic field to compute the Stokes parameters in single scattering that describe completely flux and polarization of the scattered light.Comment: 17 pages, 5 figures, Latex, accepted for publication in JQSR

Transverse confinement of waves in 3D random media

We study the transmission of a tightly focused beam through a thick slab of 3D disordered medium in the Anderson localized regime. We show that the transverse profile of the transmitted beam exhibits clear signatures of Anderson localization and that its mean square width provides a direct measure of the localization length. For a short incident pulse, the width is independent of absorption.Comment: 4 pages, 3 figure

Weak localization of short pulses in disordered waveguides

We consider the phenomenon of weak localization of a short wave pulse in a quasi-1D disordered waveguide. We show that the long-time decay of the average transmission coefficient is not purely exponential, in contradiction with predictions of the diffusion theory. The diffusion theory breaks down completely for times exceeding the Heisenberg time. We also study the survival probability of a quantum particle in a disordered waveguide and compare our results with previous calculations using the super-symmetric nonlinear sigma model.Comment: 4 pages, to appear in Acta Phys. Pol. A (Proceedings of the 2nd Workshop on Quantum Chaos and Localization Phenomena, May 19-22, 2005, Warsaw

Transfer of linear momentum from the quantum vacuum to a magnetochiral molecule

In a recent publication [Phys. Rev. Lett. 111, 143602] we have shown using a QED approach that, in the presence of a magnetic field, the quantum vacuum coupled to a chiral molecule provides a kinetic momentum directed along the magnetic field. Here we explain the physical mechanisms which operate in the transfer of momentum from the vacuum to the molecule. We show that the variation of the molecular kinetic energy originates from the magnetic energy associated with the vacuum correction to the magnetization of the molecule. We carry out a semiclassical calculation of the vacuum momentum and compare the result with the QED calculation.Comment: minor corrections made to agree with the published versio

Magneto-chiral scattering of light: a new optical manifestation of chirality

We have investigated multiple scattering of light in systems subject to magneto-chiral (MC) effects. Our medium consists of magneto-optically active dipoles placed in a chiral geometry under the influence of an external magnetic field. We have calculated, for the first time, the total and the differential scattering MC cross sections of this system, explicitely showing that they are proportional to pseudoscalar quantities. This provides a new optical measure for the degree of chirality, a pseudoscalar g, of an arbitrary geometrical configuration of scatterers based on its scattering properties. We have calculated g for some simple chiral systems and we have even used it to probe the degree of optical chirality of random systems. Finally, we have compared $g$ with other recently defined chiral measures in literature.Comment: 18 pages, 6 figures, RevTeX. Submitted to PR

Anderson Localization of Matter Waves in 3D Anisotropic Disordered Potentials

Using a cutoff-free formulation of the coherent transport theory, we show that the interference terms at the origin of localization strongly affect the transport anisotropy. In contrast to the common hypothesis, we then find that the anisotropies of incoherent and coherent diffusion are significantly different, in particular at criticality. There, we show that the coherent transport anisotropy is mainly determined by the properties of the disorder-averaged effective scattering medium while the incoherent transport contributions become irrelevant

Assimilation of satellite data and insitu data for the improvement of global radiation maps in the Netherlands

For this research, two satellite products were used to see if it was possible to improve the resolution and quality of the global radiation interpolation in the Netherlands. The first data source was from the Climate Monitoring Satellite Application Facility (CM-SAF). The second data source was the Surface Insolation under Clear and Cloudy Skies (SICCS) from the KNMI. Both products were available for the period of January 2006 to December 2011 and came in the form of images with monthly and daily averages. To combine the satellite images with the in- put provided by the KNMI’s 32 measurement stations, these interpolation/merging methods were used: Thin Plate Splines (TPS), Mean Bias interpolation (MB), Interpolated Bias interpolation (IB), Kriging with External Drift; Exponential model (KED-EXP) & Kriging with External Drift; Spherical model (KED-SPH) All these methods made use of the in-situ measurements as main input for the interpolation and all methods except TPS used the satellite products as auxiliary data. Interpolations were made for the average of the six year period and on monthly measurements, for each month, in each year. Daily interpolations were made for April 2010 until July 2010. Different validation methods were used to analyze the output. The results showed that; for the six year average both products and all interpolation methods did a good job on predicting global radiation. The R2 was lowest for the IB on the CM-SAF product with a value of 0.19. However, the MAPE (mean absolute percentage error) did not exceed 1.39% on the CM-SAF product and 1.42% on the SICCS product. These values corresponded with an absolute bias of 1.77 W/m2 and 1.8 W/m2. The monthly results showed similar results. The R2 values tended to differ more, especially in the IB and MB interpolation. In most cases this could be explained by the quality of the Satellite images. The MAPE was low in all cases. A maximum MAPE of 8.38% was found (when using proper satellite images), in November, which corresponded with an absolute bias of ± 4 W/m2. Data splitting returned similar results. MAPE’s did increase up to 9.27% when leaving out 1/4th of the measurement stations but this value corresponds with an absolute bias of 2.71W/m2. These low absolute errors showed that all interpolation methods return an accurate interpolation. However, because the interpolation methods rely on the quality of the satellite images, the SICCS product would be a better product. These images were complete in all months while the CM-SAF product lacked data in December. Since it turned out that all interpolations performed well, daily data was analyzed for the period of April until July 2010. It turned out that for the daily data KED and the IB interpolations performed significantly better than the TPS or MB interpolation. The biggest average MAPE was found for the TPS method (10.7% in May). The smallest average errorof0%wasfoundfortheIBmethod. How- ever this method was paired with very low R2 values which made the model unpredictable. The average KED R2 and MAPE ranged from 0.57 to 0.75 and from 0.08% to 0.95 %. This made the method a stable and accurate interpolation method. The satellite images on their own would not be good enough to use directly as a global radiation map, for this time interval. The over- and underestimated bias of the satellite images ranged from -89.63 to 64.49 W/m2. This showed that, a combination of station data and satellite data would improve the quality and resolution of daily global radiation maps

Magneto-electric momentum transfer to atoms and molecules

We report the first observation of mechanical momentum transferred to atoms and molecules upon application of crossed electric and magnetic fields. We identify this momentum as the microscopic analogue of the classical Abraham force. Several predictions of additional magneto-electrically induced mechanical momentum are addressed. One of them, proposed to result from the interaction with the quantum vacuum, is experimentally refuted, others are found to be currently below experimental detection.Comment: 4 pages, 3 figures, one tabl