@article{43202, abstract = {{For numerous applications, the computation and provision of exact derivative information plays an important role for optimizing the considered system. This paper introduces the technique of algorithmic differentiation, a method to compute derivatives of arbitrary order within working precision. This derivative information will be combined with a calculus-based optimization algorithm to optimize a non-trivially shaped laser pulse which coherently steers the electron dynamics in a semiconductor quantum wire. Numerical results illustrating the cost for the derivative computation and the optimization process are presented and discussed.}}, author = {{Meier, Torsten and Reichelt, Matthias and Walther, A.}}, journal = {{Photonics and Nanostructures - Fundamentals and Applications}}, number = {{4}}, pages = {{328--336}}, publisher = {{Elsevier}}, title = {{{Calculus-based optimization of the electron dynamics in nanostructures}}}, doi = {{10.1016/j.photonics.2011.03.006}}, volume = {{9}}, year = {{2011}}, } @book{41965, editor = {{Brinkmann, Annette and Burrichter, Rita and Decker, Claudia}}, publisher = {{LiT Verlag}}, title = {{{Lernprozesse professionell begleiten. Beiträge des Paderborner Grundschultages 2009 zu Diagnose und Förderung}}}, volume = {{16}}, year = {{2011}}, } @article{7993, author = {{Piegdon, Karoline A. and Offer, Matthias and Lorke, Axel and Urbanski, Martin and Hoischen, Andreas and Kitzerow, Heinz-Siegfried and Declair, Stefan and Förstner, Jens and Meier, Torsten and Reuter, Dirk and Wieck, Andreas D. and Meier, Cedrik}}, issn = {{1386-9477}}, journal = {{Physica E: Low-dimensional Systems and Nanostructures}}, number = {{10}}, pages = {{2552--2555}}, publisher = {{Elsevier BV}}, title = {{{Self-assembled quantum dots in a liquid-crystal-tunable microdisk resonator}}}, doi = {{10.1016/j.physe.2009.12.051}}, volume = {{42}}, year = {{2010}}, } @phdthesis{26184, author = {{Warkentin, Andreas}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Systematik zur funktionsorientierten Modellierung von Elektrik/ Elektronik-Systemen über den Produktlebenszyklus}}}, volume = {{279}}, year = {{2010}}, } @article{39740, author = {{Urbanski, Martin and Kinkead, Brandy and Hegmann, Torsten and Kitzerow, Heinz-Siegfried}}, issn = {{0267-8292}}, journal = {{Liquid Crystals}}, keywords = {{Condensed Matter Physics, General Materials Science, General Chemistry}}, number = {{9}}, pages = {{1151--1156}}, publisher = {{Informa UK Limited}}, title = {{{Director field of birefringent stripes in liquid crystal/nanoparticle dispersions}}}, doi = {{10.1080/02678292.2010.489160}}, volume = {{37}}, year = {{2010}}, } @article{39741, author = {{Kitzerow, Heinz-Siegfried}}, issn = {{0015-0193}}, journal = {{Ferroelectrics}}, keywords = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}}, number = {{1}}, pages = {{66--85}}, publisher = {{Informa UK Limited}}, title = {{{Blue Phases: Prior Art, Potential Polar Effects, Challenges}}}, doi = {{10.1080/00150191003683807}}, volume = {{395}}, year = {{2010}}, } @article{39972, author = {{Kitzerow, Heinz-Siegfried}}, issn = {{1439-9598}}, journal = {{Nachrichten aus der Chemie}}, keywords = {{General Chemical Engineering, General Chemistry}}, number = {{6}}, pages = {{678--679}}, publisher = {{Wiley}}, title = {{{33. Arbeitstagung Flüssigkristalle}}}, doi = {{10.1002/nadc.20050530635}}, volume = {{53}}, year = {{2010}}, } @article{39739, abstract = {{ The electrooptic characteristics of the field-induced reorientation of a nematic liquid crystal are studied using graphene layers as transparent conductive electrodes. The covering of a large area with highly conductive graphene was achieved by the thermal reduction of a graphene oxide film. The conductivity of the graphene electrode provides electrooptic properties that are comparable to those of liquid crystal cells with two conventional indium tin oxide electrodes. This result confirms earlier studies and suggestions concerning graphene-based liquid crystal devices. It demonstrates that the fabrication of graphene layers via the deposition and subsequent reduction of graphene oxide is suitable for liquid crystal applications. }}, author = {{Nordendorf, Gaby and Kasdorf, Olga and Kitzerow, Heinz-Siegfried and Liang, Yanyu and Feng, Xinliang and Müllen, Klaus}}, issn = {{0021-4922}}, journal = {{Japanese Journal of Applied Physics}}, keywords = {{General Physics and Astronomy, General Engineering}}, number = {{10R}}, publisher = {{IOP Publishing}}, title = {{{Liquid Crystal Addressing by Graphene Electrodes Made from Graphene Oxide}}}, doi = {{10.1143/jjap.49.100206}}, volume = {{49}}, year = {{2010}}, } @article{39738, author = {{Urbanski, Martin and Kinkead, Brandy and Qi, Hao and Hegmann, Torsten and Kitzerow, Heinz-Siegfried}}, issn = {{2040-3364}}, journal = {{Nanoscale}}, keywords = {{General Materials Science}}, number = {{7}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Electroconvection in nematic liquid crystals via nanoparticle doping}}}, doi = {{10.1039/c0nr00139b}}, volume = {{2}}, year = {{2010}}, } @article{39737, author = {{Lorenz, Alexander and Schuhmann, Rolf and Kitzerow, Heinz-Siegfried}}, issn = {{0003-6935}}, journal = {{Applied Optics}}, number = {{20}}, publisher = {{The Optical Society}}, title = {{{Switchable waveguiding in two liquid-crystal-filled photonic crystal fibers}}}, doi = {{10.1364/ao.49.003846}}, volume = {{49}}, year = {{2010}}, } @inproceedings{39736, author = {{Kinkead, Brandy and Urbanski, Martin and Qi, Hao and Kitzerow, Heinz-Siegfried and Hegmann, Torsten}}, booktitle = {{SPIE Proceedings}}, editor = {{Khoo, Iam Choon}}, issn = {{0277-786X}}, publisher = {{SPIE}}, title = {{{Alignment and electrooptic effects in nanoparticle-doped nematic liquid crystals}}}, doi = {{10.1117/12.858831}}, year = {{2010}}, } @article{41366, author = {{Seifert, Andreas and Schaper, Niclas}}, journal = {{Lehrerbildung auf dem Prüfstand}}, number = {{2}}, pages = {{179--198}}, title = {{{Überprüfung eines Kompetenzmodells und Messinstruments zur Strukturierung allgemeiner pädagogischer Kompetenz in der universitären Lehrerbildung.}}}, volume = {{3}}, year = {{2010}}, } @inproceedings{41463, author = {{Israel, Georgq and Seifert, Andreas and König, Johannes and Schaper, Niclas and Blömeke, Sigrid}}, booktitle = {{AEPF-Tagung „Mixed Methods in der empirischen Bildungsforschung”}}, location = {{Jena}}, title = {{{Entwicklung und empirische Überprüfung eines phasenübergreifenden Berufsfähig-keitsprofils für angehende Lehrpersonen.}}}, year = {{2010}}, } @inproceedings{42030, author = {{ Richter, D and Hafenbrak, R and Jöns, Klaus D. and Schulz, W-M and Eichfelder, M and Heldmaier, M and Roßbach, R and Jetter, M and Michler, P}}, title = {{{Low-density MOVPE grown InGaAs QDs exhibiting ultra-narrow single exciton linewidths}}}, volume = {{21}}, year = {{2010}}, } @article{8179, abstract = {{Given the density matrix rho of a bipartite quantum state, the quantum separability problem asks whether rho is entangled or separable. In 2003, Gurvits showed that this problem is NP-hard if rho is located within an inverse exponential (with respect to dimension) distance from the border of the set of separable quantum states. In this paper, we extend this NP-hardness to an inverse polynomial distance from the separable set. The result follows from a simple combination of works by Gurvits, Ioannou, and Liu. We apply our result to show (1) an immediate lower bound on the maximum distance between a bound entangled state and the separable set (assuming P != NP), and (2) NP-hardness for the problem of determining whether a completely positive trace-preserving linear map is entanglement-breaking.}}, author = {{Gharibian, Sevag}}, journal = {{Quantum Information & Computation}}, number = {{3{\&}4}}, pages = {{343--360}}, title = {{{Strong NP-hardness of the quantum separability problem}}}, volume = {{10}}, year = {{2010}}, } @article{4127, abstract = {{The dynamics of charge and spin injection currents excited by circularly polarized, one-color laser beams in semiconductor quantum wells is analyzed. Our microscopic approach is based on a 14x14 k · p band-structure theory in combination with multisubband semiconductor Bloch equations which allows a detailed analysis of the photogenerated carrier distributions and coherences in k space. Charge and spin injection currents are numerically calculated for [110]- and [001]-grown GaAs quantum wells including dc population contributions and ac contributions that arise from intersubband coherences. The dependencies of the injection currents on the excitation conditions, in particular, the photon energy are computed and discussed.}}, author = {{Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{11}}, publisher = {{American Physical Society (APS)}}, title = {{{Microscopic analysis of charge and spin photocurrents injected by circularly polarized one-color laser pulses in GaAs quantum wells}}}, doi = {{10.1103/physrevb.82.115316}}, volume = {{82}}, year = {{2010}}, } @inproceedings{4176, abstract = {{A microscopic theory that describes injection currents in GaAs quantum wells is presented. 14 × 14 band k.p theory is used to compute the band structure including anisotropy and spin-orbit interaction. Transient injection currents are obtained via numerical solutions of the semiconductor Bloch equations. Depending on the growth direction of the considered quantum well system and the propagation and polarization directions of the incident light beam, it is possible to generate charge and/or spin photocurrents on ultrashort time scales. The dependence of the photocurrents on the excitation conditions is computed and discussed.}}, author = {{Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIV}}, editor = {{Song, Jin-Joo and Tsen, Kong-Thon and Betz, Markus and Elezzabi, Abdulhakem Y.}}, keywords = {{tet_topic_qw}}, pages = {{76000S--76000S--9}}, publisher = {{SPIE}}, title = {{{Microscopic theoretical analysis of optically generated injection currents in semiconductor quantum wells}}}, doi = {{10.1117/12.840388}}, volume = {{7600}}, year = {{2010}}, } @article{24980, abstract = {{We discuss transport and localization properties on the insulating side of the disorder dominated superconductor-insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence of phonons, we argue that the Bose glass phase admits three distinct regimes. For strongest disorder the boson system is a fully localized, perfect insulator at any temperature. At smaller disorder, only the low temperature phase exhibits perfect insulation while delocalization takes place above a finite temperature. We argue that a third phase must intervene between these perfect insulators and the superconductor. This conducting Bose glass phase is characterized by a mobility edge in the many body spectrum, located at finite energy above the ground state. In this insulating regime purely electronically activated transport occurs, with a conductivity following an Arrhenius law at asymptotically low temperatures, while a tendency to superactivation is predicted at higher T. These predictions are in good agreement with recent transport experiments in highly disordered films of superconducting materials.}}, author = {{Gögh, N. and Thomas, P. and Kuznetsova, I. and Meier, Torsten and Varga, I.}}, issn = {{0003-3804}}, journal = {{Annalen der Physik}}, number = {{12}}, pages = {{905--909}}, title = {{{Localization of excitons in weakly disordered semiconductor structures: A model study}}}, doi = {{10.1002/andp.20095211219}}, volume = {{18}}, year = {{2010}}, } @article{23480, abstract = {{We discuss transport and localization properties on the insulating side of the disorder dominated superconductor-insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence of phonons, we argue that the Bose glass phase admits three distinct regimes. For strongest disorder the boson system is a fully localized, perfect insulator at any temperature. At smaller disorder, only the low temperature phase exhibits perfect insulation while delocalization takes place above a finite temperature. We argue that a third phase must intervene between these perfect insulators and the superconductor. This conducting Bose glass phase is characterized by a mobility edge in the many body spectrum, located at finite energy above the ground state. In this insulating regime purely electronically activated transport occurs, with a conductivity following an Arrhenius law at asymptotically low temperatures, while a tendency to superactivation is predicted at higher T. These predictions are in good agreement with recent transport experiments in highly disordered films of superconducting materials.}}, author = {{Gögh, N. and Thomas, P. and Kuznetsova, I. and Meier, Torsten and Varga, I.}}, issn = {{0003-3804}}, journal = {{Annalen der Physik}}, number = {{12}}, pages = {{905--909}}, title = {{{Localization of excitons in weakly disordered semiconductor structures: A model study}}}, doi = {{10.1002/andp.200910382}}, year = {{2010}}, } @inproceedings{2223, author = {{Lübbers, Enno and Platzner, Marco and Plessl, Christian and Keller, Ariane and Plattner, Bernhard}}, booktitle = {{Proc. Int. Conf. on Engineering of Reconfigurable Systems and Algorithms (ERSA)}}, isbn = {{1-60132-140-6}}, pages = {{225--231}}, publisher = {{CSREA Press}}, title = {{{Towards Adaptive Networking for Embedded Devices based on Reconfigurable Hardware}}}, year = {{2010}}, }