@article{40199, author = {{Brańczyk, Agata M and Ralph, T C and Helwig, Wolfram and Silberhorn, Christine}}, issn = {{1367-2630}}, journal = {{New Journal of Physics}}, keywords = {{General Physics and Astronomy}}, number = {{6}}, publisher = {{IOP Publishing}}, title = {{{Optimized generation of heralded Fock states using parametric down-conversion}}}, doi = {{10.1088/1367-2630/12/6/063001}}, volume = {{12}}, year = {{2010}}, } @inbook{43260, author = {{Güdde, J. and Rohleder, M. and Meier, Torsten and Koch, S.W. and Höfer, U.}}, booktitle = {{Dynamics at Solid State Surfaces and Interfaces}}, editor = {{Bovensiepen, U. and Petek, H. and Wolf, M.}}, pages = {{579--591}}, publisher = {{Wiley‐VCH Verlag}}, title = {{{Coherently controlled electrical currents at surfaces}}}, doi = {{10.1002/9783527633418.ch24}}, volume = {{1}}, 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{43261, abstract = {{We report the development of an experimental technique to measure the dynamics of electrical currents on the femtosecond timescale. The technique combines methods of coherent control with time- and angle-resolved photoelectron spectroscopy. Direct snapshots of the momentum distribution of the excited electrons as function of time are then determined by photoelectron spectroscopy. In this way we gain information on the generation and decay of ultrashort current pulses in unprecedented detail. In particular, this technique allows the observation of elastic electron scattering in terms of an incoherent population dynamics in momentum space. We have applied this optical current generation and detection scheme to electrons in so-called image-potential states which represent a prototype of two-dimensional electronic surface states. Electrons in these states are bound perpendicular to the metal surface by the Coulombic image potential whereas they can move almost freely parallel to the surface. For the (n=1) image-potential state of Cu(100) we find a decay time of 10 fs due to electron scattering with steps and surface defects.}}, author = {{Güdde, J. and Rohleder, M. and Meier, Torsten and Koch, S.W. and Höfer, U.}}, booktitle = {{Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIV}}, editor = {{Song, Jin-Joo and Tsen, Kong-Thon and Betz, Markus and Y. Elezzabi, Abdulhakem}}, publisher = {{SPIE}}, title = {{{Ultrafast coherent control of electric currents at metal surfaces}}}, doi = {{10.1117/12.839672}}, volume = {{7600}}, 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{44063, abstract = {{We present an analysis of the coupling between photonic crystal cavities in different geometries. Inline‐, side‐ and angle‐coupled L3‐geometries are investigated numerically in three dimensions. Asymmetric mode splitting of the fundamental mode for the L3‐cavity is shown for all geometrical setups evidencing for strong cavity‐cavity interactions. The coupling efficiency for the fundamental mode is shown to be best for a 30° angle between the cavity‐centers due to the direction of in‐plane leackage out of the cavites.}}, author = {{Meier, Torsten and Declair, S. and Förstner, J.}}, journal = {{AIP Conference Proceedings}}, number = {{46 }}, publisher = {{American Institute of Physics}}, title = {{{Numerical Analysis of Coupled Photonic Crystal Cavities}}}, doi = {{10.1063/1.3506125}}, volume = {{1291}}, 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}}, } @article{18558, abstract = {{We present an implementation of the GW approximation for the electronic self-energy within the full-potential linearized augmented-plane-wave (FLAPW) method. The algorithm uses an all-electron mixed product basis for the representation of response matrices and related quantities. This basis is derived from the FLAPW basis and is exact for wave-function products. The correlation part of the self-energy is calculated on the imaginary-frequency axis with a subsequent analytic continuation to the real axis. As an alternative we can perform the frequency convolution of the Green function G and the dynamically screened Coulomb interaction W explicitly by a contour integration. The singularity of the bare and screened interaction potentials gives rise to a numerically important self-energy contribution, which we treat analytically to achieve good convergence with respect to the k-point sampling. As numerical realizations of the GW approximation typically suffer from the high computational expense required for the evaluation of the nonlocal and frequency-dependent self-energy, we demonstrate how the algorithm can be made very efficient by exploiting spatial and time-reversal symmetry as well as by applying an optimization of the mixed product basis that retains only the numerically important contributions of the electron-electron interaction. This optimization step reduces the basis size without compromising the accuracy and accelerates the code considerably. Furthermore, we demonstrate that one can employ an extrapolar approximation for high-lying states to reduce the number of empty states that must be taken into account explicitly in the construction of the polarization function and the self-energy. We show convergence tests, CPU timings, and results for prototype semiconductors and insulators as well as ferromagnetic nickel.}}, author = {{Friedrich, Christoph and Blügel, Stefan and Schindlmayr, Arno}}, issn = {{1550-235X}}, journal = {{Physical Review B}}, number = {{12}}, publisher = {{American Physical Society}}, title = {{{Efficient implementation of the GW approximation within the all-electron FLAPW method}}}, doi = {{10.1103/PhysRevB.81.125102}}, volume = {{81}}, year = {{2010}}, } @inproceedings{44064, abstract = {{We compute photocurrents generated by femtosecond single-color laser pulses in non-centrosymmetric semiconductor quantum wells by combining a 14 x 14 k.p band structure theory with multi-band semiconductor Bloch equations. The transient photocurrents are investigated experimentally by measuring the associated Terahertz emission. The dependencies of the photocurrent and the Terahertz emission on the excitation conditions are discussed for (110)-oriented GaAs quantum wells. The comparison between theory and experiment shows a good agreement.}}, author = {{Meier, Torsten and Duc, Huynh Thanh and Foerstner, Jens and Priyadarshi, S. and Racu, Ana Maria and Pierz, Klaus and Siegner, Uwe and Bieler, Mark}}, booktitle = {{DPG Spring meeting 2010 }}, issn = {{0420-0195}}, location = {{Regensburg, Germany}}, number = {{3}}, title = {{{Experimental and theoretical investigations of photocurrents in non-centrosymmetric semiconductor quantum wells}}}, volume = {{45}}, year = {{2010}}, } @inproceedings{44067, abstract = {{Semiconductor nanostructures always contain a certain degree of disorder due to interface roughness and/or alloy disorder. The disorder has significant influence on the optical properties, e.g., excitonic absorption spectra. An adaptive wavelet approach for the solution of the excitonic Schroedinger equation, i.e., the semiconductor Bloch equation for the interband coherence linear in the external field, has been developed and applied to compute absorption spectra and/or wave functions. Results obtained for a thin GaAs semiconductor quantum wire considering a number of different model disorder potentials are presented and discussed.}}, author = {{Meier, Torsten and Mollet, Christian and Kunoth, Angela}}, booktitle = {{DPG Spring meeting 2010}}, issn = {{ 0420-0195}}, location = {{Regensburg, Germany}}, number = {{3}}, title = {{{A numerical adaptive wavelet approach to excitonic absorption spectra of disordered semiconductor nanostructures}}}, volume = {{45}}, year = {{2010}}, } @inproceedings{44065, abstract = {{The behavior of waveguide plasmon polaritons is studied employing ultrafast coherent control like schemes for a gold lattice coupled to a photonic waveguide for the structure. Different models to describe the third-harmonic generation are presented and the resulting equations are solved numerically. The calculations are compared to recent experimental data and show good agreement for the most prominent features in the time-integrated third order intensity.}}, author = {{Meier, Torsten and Podzimski, Reinold and Reichelt, Matthias and Utikal, Tobias and Giessen, Harald}}, booktitle = {{DPG Spring meeting 2010}}, issn = {{0420-0195}}, location = {{Regensburg, Germany}}, number = {{3}}, title = {{{Controlling the third-harmonic generation in a metallic photonic crystal coupled to a waveguide}}}, volume = {{45}}, year = {{2010}}, } @inproceedings{44066, abstract = {{We present a joint theoretical study of the optical properties of GaAs and AlAs bulk and heterostructures. Thereby, we compare the theoretical description of optical excitation on several levels of theory. Results obtained from kp theory are discussed along with data from ab initio calculations within the frameworks of independent-particle (DFT), independent quasiparticle (GW), or Coulomb-correlated quasiparticle (BSE) approximation.}}, author = {{Meier, Torsten and Landmann, Marc and Pochwala, Michal and Foerstner, Jens and Rauls, Eva and Schmidt, Wolf Gero}}, booktitle = {{DPG Spring meeting 2010}}, issn = {{0420-0195}}, location = {{Regensburg, Germany}}, number = {{3}}, title = {{{Theoretical description of optical properties in III-V semiconductor nanostructures}}}, volume = {{45}}, year = {{2010}}, } @article{45294, author = {{Riese, Josef}}, journal = {{PhyDid – Physik und Didaktik in Schule und Hochschule}}, pages = {{25--33}}, title = {{{Empirische Erkenntnisse zur Wirksamkeit der universitären Lehrerbildung – Indizien für notwendige Veränderungen der fachlichen Ausbildung von Physiklehrkräften}}}, volume = {{9}}, year = {{2010}}, } @article{45293, author = {{Riese, Josef and Reinhold, Peter}}, journal = {{Zeitschrift für Didaktik der Naturwissenschaften}}, pages = {{167--187}}, title = {{{Empirische Erkenntnisse zur Struktur professioneller Handlungskompetenz von angehenden Physiklehrkräften}}}, volume = {{16}}, year = {{2010}}, } @article{45292, author = {{Borowski, Andreas and Riese, Josef}}, journal = {{Praxis der Naturwissenschaften Physik in der Schule}}, number = {{5}}, pages = {{5--8}}, title = {{{Physikalisch-fachdidaktisches Wissen – Was kommt in der Praxis an?}}}, volume = {{59}}, year = {{2010}}, } @inproceedings{45540, author = {{Borowski, Andreas and Fischer, Hans and Olszewski, Jennifer and Reinhold, Peter and Riese, Josef}}, booktitle = {{Entwicklung naturwissenschaftlichen Denkens zwischen Phänomen und Systematik. Gesellschaft für Didaktik der Chemie und Physik. Jahrestagung in Dresden 2009}}, editor = {{Höttecke, Dietmar}}, pages = {{377--379}}, title = {{{Ein Vergleich von Tests zum fachdidaktischen Wissen von Physiklehrkräften}}}, year = {{2010}}, } @inproceedings{45541, author = {{Borowski, Andreas and Fischer, Hans and Olszewski, Jennifer and Reinhold, Peter and Riese, Josef and Vogelsang, Christoph}}, booktitle = {{Entwicklung naturwissenschaftlichen Denkens zwischen Phänomen und Systematik. Gesellschaft für Didaktik der Chemie und Physik. Jahrestagung in Dresden 2009}}, editor = {{Höttecke, Dietmar}}, pages = {{365--367}}, title = {{{Professionswissen von Physiklehrkräften}}}, year = {{2010}}, } @inproceedings{45542, author = {{Riese, Josef and Reinhold, Peter}}, booktitle = {{Entwicklung naturwissenschaftlichen Denkens zwischen Phänomen und Systematik. Gesellschaft für Didaktik der Chemie und Physik. Jahrestagung in Dresden 2009}}, editor = {{Höttecke, Dietmar}}, pages = {{368--370}}, title = {{{Entwicklung und Struktur Physik-bezogener Kompetenz im Lehramtsstudium}}}, year = {{2010}}, } @inproceedings{45539, author = {{Riese, Josef and Reinhold, Peter}}, booktitle = {{Contemporary science education research: teaching}}, editor = {{Taşar, Mehmet Fatih and Çakmakci, Gültekin}}, pages = {{79--85; 91--94}}, title = {{{Measuring physics student teachers’ pedagogical content knowledge as an indicator of their professional action competence}}}, year = {{2010}}, }