A5035925808- Random lasers and scattering media
- Photonic Crystals and Applications
- Photonic and Optical Devices
- Quantum optics and atomic interactions
- Strong Light-Matter Interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Neural Networks and Reservoir Computing
- Functional Brain Connectivity Studies
- Medical Imaging Techniques and Applications
- Computer Graphics and Visualization Techniques
- Terahertz technology and applications
- Plasmonic and Surface Plasmon Research
- Advanced Optical Imaging Technologies
- Data Visualization and Analytics
- Health Systems, Economic Evaluations, Quality of Life
- Topological Materials and Phenomena
- Quantum many-body systems
- Advanced MRI Techniques and Applications
- Mechanical and Optical Resonators
- Orbital Angular Momentum in Optics
- Advanced Neuroimaging Techniques and Applications
- Quantum Mechanics and Applications
- Surface Roughness and Optical Measurements
- Computational Physics and Python Applications
- Medical Image Segmentation Techniques
Karlsruhe Institute of Technology
2009-2021
University of Bonn
2006-2020
Rutgers, The State University of New Jersey
2019-2020
University of the Basque Country
2019
Ikerbasque
2019
University of Tübingen
2006-2015
Stellenbosch University
2014
National Institute for Theoretical Physics
2014
Institute of High Energy Physics
2013
University of Stuttgart
2006
Four pixel-based methods for estimating regional activation in positron emission tomography (PET) images were implemented so as to allow the comparison of their performances same dataset. Change distribution analysis, Worsley's method, a pixelwise general linear model, nonparametric and several derived from them investigated. Important technical factors, including degree smoothing, stereotactic transform, coregistration algorithm, search volume, volumetric alpha level, held constant. The...
This paper describes methods for explanatory and illustrative visualizations used to communicate aspects of Einstein's theories special general relativity, their geometric structure, the related fields cosmology astrophysics. Our illustrations target a audience laypersons interested in relativity. We discuss visualization strategies, motivated by physics education didactics mathematics, describe what kind have proven be useful different types media, such as still images popular science...
Meeting the demands of current tera-scale visualization community requires use large- and small-scale tiled displays. The Lawrence Livermore National Laboratory (LLNL) efforts in this area have led to creation one largest interactive displays built date, a number new for "personal" Visualization hardware software now being will display up 15 times pixels typical desktop display. We outline system implemented at LLNL support large, tiled, multi-pipe graphics builds on simple, portable,...
We present a systematical theory for the interplay of strong localization effects and absorption or gain classical waves in three-dimensional, disordered dielectrics. The is based on self-consistent Cooperon resummation, implementing energy conservation its absorptive emissive corrections by an exact, generalized Ward identity. Substantial renormalizations are found, depending whether occurs scatterers background medium. find finite, gain-induced correlation volume which may be significantly...
We study the coherent properties of plasmon polaritons optically excited on periodic nanostructures. The gold grains are coupled to a single mode photonic waveguide which exhibits dramatically reduced transmission originating from derived quantum interference. With nonequilibrium description Floquet-dressed we demonstrate switching light through due sheer existence intraband transitions in right above Fermi level driven by external laser light.
Spatially uniform optical excitations can induce Floquet topological band structures within insulators which develop similar or equal characteristics as are known from three-dimensional insulators. We derive in this article theoretically the development of quantum states for electromagnetically driven semiconductor bulk matter and we present results lifetime these their occupation non-equilibrium. The direct physical impact mathematical precision Floquet-Keldysh theory is evident when solve...
We present a detailed discussion of scalar wave propagation and light intensity transport in three-dimensional random dielectric media with optical gain. The intrinsic length time scales such amplifying systems are studied comprehensively discussed as well the threshold characteristics single- two-particle propagators. Our semianalytical theory is based on self-consistent Cooperon resummation, representing repeated self-interference, incorporates gain absorption, modeled way by finite...
An ultracold gas of interacting fermionic atoms in a three-dimensional optical lattice is considered, where the potential strength periodically modulated. This non-equilibrium system non-perturbatively described by means Keldysh–Floquet–Green's function approach for Mott–Hubbard systems employing generalized dynamical mean field theory (DMFT). Strong repulsive interactions between different lead to Mott insulator state equilibrium system, but additional external driving at zero temperature...
We present a quantum field theoretical method for the characterization of disordered complex media with short laser pulses in an optical coherence tomography setup (OCT). solve this scheme coherent transport space and time weighted essentially nonoscillatory methods (WENO). WENO is preferentially used determination highly nonlinear discontinuous processes including interference effects phase transitions like Anderson localization light. The theory determines spatiotemporal characteristics...
We implement externally excited ZnO Mie resonators in a framework of generalized Hubbard Hamiltonian to investigate the lifetimes excitons and exciton-polaritons out thermodynamical equilibrium. Our results are derived by Floquet-Keldysh-Green’s formalism with Dynamical Mean Field Theory (DMFT) second order iterative perturbation theory solver (IPT). find that Fano resonance which originates from coupling continuum electronic density states semiconductor resonator yields polaritons between...
We present a distributed framework that enables real-time streaming and visualization of data generated by large remote simulations. address issues arising from clientserver environments guarantee good parallel load balancing. apply progressive computing techniques parallel, hierarchical to reduce the "distance" between simulation hardware systems where actual analysis occur. simple efficient balancing method scales arbitrary sizes does not introduce additional communication cost....
We report a theoretical non-equilibrium description of polaritonics and we propose ultrafast all- optical switching due to highly nonlinear polaritonics. The electronic band structure within gold (Au) nano grains is modified by external laser light. Au are coupled single mode photonic waveguide derive strong transmission reduction originating from the establishd quantum interference with finite lifetime.
Abstract We report and validate a technique for magnetic resonace imaging (MRI) positron emission tomography (PET) coregistration the optimization of PET slice orientation that enhances complements existing techniques. The depends on an external fiducial system software models relationship gantry with respect to three‐dimensional (3D) MR reconstruction each subject's brain anatomy. offers possibility using individual neuroanatomical information plan activation studies. Estimated 3D errors...
The spatial formation of coherent random laser modes in strongly scattering disordered media is a central feature the understanding physics lasers. We derive quantum field theoretical method for lasing samples complex amplifying Mie resonators which able to provide self-consistently and free any fit parameter full set transport characteristics at above phase transition. coherence length correlation volume respectively derived as an experimentally measurable scale transition threshold. find...
Spatially uniform optical excitations can induce Floquet topological band structures within insulators which develop similar or equal characteristics as are known from three-dimensional insulators. We derive in this article theoretically the development of quantum states for electromagnetically driven semiconductor bulk matter and we present results lifetime these their occupation non-equilibrium. The direct physical impact mathematical precision Floquet-Keldysh theory is evident when solve...
We present the application of hardware accelerated volume rendering algorithms to simulation radiographs as an aid scientists designing experiments, validating codes, and understanding experimental data. The techniques presented take advantage 32-bit floating point texture capabilities obtain solutions radiative transport equation for X-rays. are accurate enough enable explore design space with greater efficiency than methods currently in use. An unsorted hexahedron projection algorithm is...
Abstract We report the theoretical analysis for tuning quantum efficiency of solid state random lasers. Vollhardt-Wölfle theory photonic transport in disordered non-conserving and open media, is coupled to lasing dynamics solved positionally dependent. The interplay non-linearity homogeneous non-radiative frequency conversion by means a Stokes-shift leads reduction laser. At threshold strong decrease spot-size stationary found due increase losses. coherently emitted photon number per unit...
We present diagrammatic transport theory including self-consistent nonlinear enhancement and dissipation in the multiple scattering regime. Our model of Vollhardt-W\"olfle photons is fit-parameter-free raises claim that results hold up to closest packed volume randomly arranged ZnO Mie scatterers. find a symmetry breaking caused by dissipative effects lossy underlying substrate leads qualitatively different physics coherence lasing granular amplifying media. According our results, confined...