Global ETD Search

31	Investigations of transport phenomena and dynamical relaxation in closed quantum systems Khodja, Abdellah 17 March 2015 (has links) The first part of the present Phd thesis is devoted to transport investigations in disordered quantum systems. We aim at quantitatively determining transport parameters like conductivity, mean free path, etc., for simple models of spatially disordered and/or percolated quantum systems in the limit of high temperatures and low fillings using linear response theory. We find the transport behavior for some models to be in accord with a Boltzmann equation, i.e., long mean free paths, exponentially decaying currents although there are no band-structures to start from, while this does not apply to other models even though they are also almost completely delocalized. The second part of the present PhD thesis addresses the issue of initial state independence (ISI) in closed quantum system. The relevance of the eigenstate thermalization hypothesis (ETH) for the emergence of ISI equilibration is to some extent addressed. To this end, we investigate the Heisenberg spin-ladder and check the validity of the ETH for the energy difference operator by examining the scaling behavior of the corresponding ETH-fluctuations, which we compute using an innovative numerical method based on typicality related arguments. While, the ETH turns out to hold for the generic non-integrable models and may therefore serve as the key mechanism for ISI for this cases, it does not hold for the integrable Heisenberg-chain. However, close analysis on the dynamic of substantially out-of-equilibrium initial states indicates the occurrence of ISI equillibration in the thermodynamic limit regardless of whether the ETH is violated. Thus, we introduce a new parameter $v$, which we propose as an alternative of the ETH to indicate ISI equillibration in cases, in which the ETH does not strictly apply. transport coefficients Boltzmann equation eigenstate thermalization hypothesis 33.23 - Quantenphysik 33.10 - Theoretische Physik: Allgemeines 33.66 - Amorpher Zustand, Gläser ddc:530
32	Dynamics of Population Coding in the Cortex / Dynamische Populationskodierung im Gehirn Naundorf, Björn 28 June 2005 (has links) No description available. 530 Physik Mathematics and Computer Science Spike initiation Population coding Hodgkin-Huxley model Neuron models Phase Oscillator In vivo Intracellular recordings Cortical neurons Aktionspotentialinitiierung Populationskodierung Hodgkin-Huxley Theorie Modellneurone Phasenoszillator In vivo intrazelluläre Ableitungen Kortikale Neurone 33.10 33.20 30.30 44.3 RDI 000: Theoretische Physik
33	Transport in nicht-hermiteschen niedrigdimensionalen Systemen / Transport in Non-Hermitian Low-Dimensional Systems Bendix, Oliver 20 September 2011 (has links) No description available. 530 Physik Physics Ballistischer Transport Lichttransport Greensche Funktionen Landauer-Büttiker-Formalismus Müllerzellen Photonik Wellenleiter PT-Symmetrie Unordnung Quantenmechanik Streuformalismus ballistic transport light transport Greens functions Landauer-Büttiker-formalism Müller cells photonic waveguides PT-symmetry disorder quantum mechanics scattering formalism 33.10 RDI 240: Streutheorie quantenmechanische {Theoretische Physik}
34	Modelling and simulation of surface morphology driven by ion bombardment / Modellieren und Simulation der Oberflächenmorphologie gefahren durch Ionenbombardierung Yewande, Emmanuel Oluwole 02 May 2006 (has links) No description available. 530 Physik Mathematics and Computer Science Non-equilibrium Oberflächen Ionenbombardierung Selbst--organisierte nano Muster Monte-Carlo Simulation Kontinuumtheorie die coarsening Kräuselung Topographie Quantenpunkt Non-equilibrium surfaces ion bombardment self-organized nano patterns Monte Carlo simulation continuum theory ripple coarsening topography quantum dot 33.06 33.10 33.68 RTF 400: Ionenimplantation {Physik}
35	Multiphase coexistence with sequence fractionation in random block copolymers / Multi-Phasenkoexistenz mit Sequenz-Fraktionierung in statistischen Block-Copolymeren von der Heydt, Alice 23 September 2011 (has links) No description available. 530 Physik Physics statistische Physik statistisches Blockcopolymer Sequenz-Fraktionierung Phasenkoexistenz homogen strukturiert Segregation kontinuierlicher Phasenübergang multikritischer Punkt statistical physics random block copolymer sequence fractionation phase coexistence homogeneous structured segregation continuous phase transition multicritical point 33.10 33.25 33.64 RDI 700: Statistische Physik Quantenstatistik SWK 600: Block-Copolymere Graft-Copolymere Polymergemische {Makromolekulare Chemie}
36	Synchronization, Neuronal Excitability, and Information Flow in Networks of Neuronal Oscillators / Synchronisation, Neuronale Erregbarkeit und Informations-Fluss in Netzwerken Neuronaler Oszillatoren Kirst, Christoph 28 September 2011 (has links) No description available. 530 Physik RDH 200 RDI 000 WC 000 WE 000 Physics Synchronisation neuronale Erregbarkeit Informationsfluss neuronale Oszillationen puls-gekopplete Oszillatoren Phasen-Oszillatoren dynamic clamp Informationsleitung modulare Netzwerke synchronization neuronal excitability information flow neuronal oscillations pulse-coupled oscillators phase oscillators dynamic clamp dynamic grouping information routing modular networks 33.10 30.20 42.12
37	Thermodynamic and spectral properties of quantum many-particle systems / Thermodynamische und spektrale Eigenschaften quantenmechanischer Vielteilchensysteme Fuchs, Sebastian 21 January 2011 (has links) No description available. 530 Physik Physics Hubbard-Modell Maximum-Entropie Quanten-Monte-Carlo kalte Atome korrelierte Elektronen Hubbard model maximum entropy quantum Monte Carlo quantum cluster theories dynamical cluster appoximation cold atoms correlated electrons 33.61 33.10 33.06 33.23 33.25 RDI 700: Statistische Physik Quantenstatistik RLA 000: Tieftemperaturphysik
38	Scale-free Fluctuations in in Bose-Einstein Condensates, Quantum Dots and Music Rhythms / Skalenfreie Fluktuationen in Bose-Einstein Kondensaten, Quantenpunkten und Musikrhythmen Hennig, Holger 27 May 2009 (has links) No description available. 530 Physik Mathematics and Computer Science Nichtlineare Dynamik Mesoskopische Physik Bose-Einstein Kondensation Soliton Breather Elektronischer Transport Leitwertfluktuationen skalenfrei fraktal langreichweitige Korrelationen Musikwahrnehmung Musikrhythmen nonlinear dynamics mesoscopic physics bose-einstein condensation soliton discrete breather electronic transport conductance fluctuations scale-free fractal long-range correlations music perception music rhythms 30.20 33.10 33.28 33.61 RDI 000: Theoretische Physik RV 000: Kondensierte Materie {Physik} RVC 850: Transporteigenschaften RDI 700: Statistische Physik Quantenstatistik RPI 000: Quantenoptik {Physik}
39	Ab-initio-Untersuchungen von Oberflächen- und Bulksystemen Greuling, Andreas 21 December 2010 (has links) In dieser Arbeit setzen wir ab-initio-Methoden zur Untersuchung einiger Oberflächensysteme und eines Bulksystems ein. Im Wesentlichen greifen wir hierbei auf die Dichtefunktionaltheorie (DFT) und die GW-Approximation (GWA) im Rahmen der Vielteilchenstörungstheorie zurück. Wir nutzen diese Methoden um die Adsorption von TMA auf der Rutil TiO2-Oberfläche zu untersuchen, optische Spektren von TiO2 zu berechnen und um die Adsorption von [7]-HCA auf der Calcit(10-14)-Oberfläche zu verstehen. Weiterhin beschäftigen wir uns intensiv mit PTCDA auf Ag(111), welches mit einer chemisch kontaktierten STM-Spitze manipuliert wird. 33.10 - Theoretische Physik: Allgemeines A70 - Theses and postdoctoral theses 65Z05 - Applications to physics J.2 - PHYSICAL SCIENCES AND ENGINEERING 73.63.Rt - Nanoscale contacts 68.37.Ps - Atomic force microscopy (AFM) 68.43.Fg - Adsorbate structure 71.20.Nr - Semiconductor compounds 71.15.Qe - Excited states: methodology 68.37.Ef - Scanning tunneling microscopy ddc:530

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