@inproceedings{4247, abstract = {{We numerically investigate strong light-matter interaction and normal mode coupling/splitting in a system composed of a single two-level atom and the localized mode of a small mode volume photonic crystal nanocavity.}}, author = {{Förstner, Jens and Dineen, Colm and Zakharian, A.R. and Moloney, Jerome V. and Koch, Stephan W.}}, booktitle = {{Frontiers in Optics}}, isbn = {{1557527970}}, publisher = {{OSA}}, title = {{{Normal Mode Coupling in Photonic Crystal Nanocavities}}}, doi = {{10.1364/fio.2005.fwc2}}, year = {{2005}}, } @article{4249, abstract = {{The interaction of electrons with LO phonons provides an important mechanism of optical dephasing and carrier scattering for the two-dimensional electron gas in semiconductor quantum wells. In this paper, the corresponding ultrafast nonlinearities for off-resonant and resonant intersubband excitations are investigated. Quantum kinetic effects of the electron-phonon interaction and the corresponding violation of the microscopic energy conservation yield a qualitative different picture compared to the standard Markovian theory, if the phonon energy is larger than the intersubband-gap energy.}}, author = {{Butscher, Stefan and Förstner, Jens and Waldmüller, Inès and Knorr, Andreas}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{4}}, pages = {{045314--045314--4}}, publisher = {{American Physical Society (APS)}}, title = {{{Ultrafast electron-phonon interaction of intersubband transitions: Quantum kinetics from adiabatic following to Rabi-oscillations}}}, doi = {{10.1103/physrevb.72.045314}}, volume = {{72}}, year = {{2005}}, } @inproceedings{4251, abstract = {{A system of two quantum dots coupled by dipole‐dipole interaction is investigated within a density matrix approach. We compute the temporal evolution of the system in the linear and nonlinear optical regime and discuss the possibility of performing basic quantum information gates. The influence of the Förster energy transfer on Rabi oscillations is discussed.}}, author = {{Danckwerts, J. and Förstner, Jens and Knorr, A.}}, booktitle = {{AIP Conference Proceedings}}, issn = {{0094-243X}}, keywords = {{tet_topic_qd}}, publisher = {{AIP}}, title = {{{Quantum information processing using Coulomb-coupled quantum dots}}}, doi = {{10.1063/1.1994668}}, volume = {{772}}, year = {{2005}}, } @article{4252, abstract = {{The electromagnetic field of a high-quality photonic crystal nanocavity is computed using the finite difference time domain method. It is shown that a separatrix occurs in the local energy flux discriminating between predominantly near and far field components. Placing a two-level atom into the cavity leads to characteristic field modifications and normalmode splitting in the transmission spectra.}}, author = {{Dineen, C. and Förstner, Jens and Zakharian, A.R. and Moloney, J.V. and Koch, S.W.}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_phc}}, number = {{13}}, publisher = {{The Optical Society}}, title = {{{Electromagnetic field structure and normal mode coupling in photonic crystal nanocavities}}}, doi = {{10.1364/opex.13.004980}}, volume = {{13}}, year = {{2005}}, } @article{4254, abstract = {{A microscopic description based on the density matrix formalism is developed to describe the dynamics of photoemission of hot electrons at semiconductor surfaces, including the interaction of bulk and surface states. The equations of motion for the electronic occupations and transitions include the interaction with arbitrary optical fields as well as the electron-phonon coupling. Model wave functions are used to qualitatively describe the bulk-surface dynamics and the subsequent time resolved two-photon photoemission s2PPEd spectra. Our results suggest that it is possible to extract energetic and temporal information of the underlying dynamical occupations of the intermediate states from the 2PPE spectra.}}, author = {{Zeiser, A. and Bücking, N. and Förstner, Jens and Knorr, A.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{24}}, publisher = {{American Physical Society (APS)}}, title = {{{Microscopic theory of electron dynamics and time-resolved two-color two-photon photoemission at semiconductor surfaces}}}, doi = {{10.1103/physrevb.71.245309}}, volume = {{71}}, year = {{2005}}, } @inproceedings{4258, abstract = {{A theoretical description of ultrafast phonon induced electronic transport between surface and bulk states after optical excitation is presented. In particular, the influence of the electron transfer processes on two photon photo emission is evaluated. }}, author = {{Bucking, N. and Zeiser, A. and Förstner, Jens and Knorr, A.}}, booktitle = {{2005 Quantum Electronics and Laser Science Conference}}, isbn = {{1557527962}}, pages = {{1929--1931}}, publisher = {{IEEE}}, title = {{{Kinetic theory of the electron transport in the two photon photo emission at semiconductor surfaces}}}, doi = {{10.1109/qels.2005.1549331}}, year = {{2005}}, } @inproceedings{4259, abstract = {{The ultrafast intersubband dynamics in a semiconductor quantum well subband system is investigated theoretically. Non-Markovian electron-phonon interaction leads to polaron formation and enhanced dephasing. }}, author = {{Butscher, S. and Förstner, Jens and Waldmuller, I. and Knorr, A.}}, booktitle = {{2005 Quantum Electronics and Laser Science Conference}}, isbn = {{1557527962}}, pages = {{640--642}}, publisher = {{IEEE}}, title = {{{Ultrafast quantum kinetics of semiconductor intersubband transitions: polaron signatures and dephasing dynamics}}}, doi = {{10.1109/qels.2005.1548881}}, year = {{2005}}, } @article{4260, abstract = {{Using a fully quantized description of strongly confined electrons interacting with acoustic phonons and the photon field, the nonstationary resonance-fluorescence spectra of a semiconductor quantum dot are investigated. For excitation pulses with durations approaching typical electron-phonon scattering times, the virtual quantum processes yield an observable electron-phonon sideband broadening.}}, author = {{Ahn, K. J. and Förstner, Jens and Knorr, A.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qd}}, number = {{15}}, publisher = {{American Physical Society (APS)}}, title = {{{Resonance fluorescence of semiconductor quantum dots: Signatures of the electron-phonon interaction}}}, doi = {{10.1103/physrevb.71.153309}}, volume = {{71}}, year = {{2005}}, } @article{4262, abstract = {{Time-dependent two-photon photoemission spectra are used to resolve the femtosecond dynamics of hot electrons at the energetically lowest surface resonance of reconstructed InP(100). Two different cases are studied, where electrons either are lifted into the surface resonance via a direct optical transition or are captured from bulk states. These data are the first of this kind recorded with a time resolution below 70 fs. The microscopic analysis shows that electron-phonon scattering is a major mechanism for electron transfer between surface and bulk states.}}, author = {{Töben, L. and Gundlach, L. and Ernstorfer, R. and Eichberger, R. and Hannappel, T. and Willig, F. and Zeiser, A. and Förstner, Jens and Knorr, A. and Hahn, P. H. and Schmidt, W. G.}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, number = {{6}}, publisher = {{American Physical Society (APS)}}, title = {{{Femtosecond Transfer Dynamics of Photogenerated Electrons at a Surface Resonance of Reconstructed InP(100)}}}, doi = {{10.1103/physrevlett.94.067601}}, volume = {{94}}, year = {{2005}}, } @article{4264, abstract = {{We demonstrate that the temporal pulse phase remains essentially unaltered before separate phase characteristics are developed when propagating high-intensity pulses coherently on the exciton resonance of an optically thick semiconductor. This behavior is a clear manifestation of self-induced transmission and pulse breakup into solitonlike pulses due to Rabi flopping of the carrier density. Experiments using a novel fast-scan cross-correlation frequency-resolved optical gating (XFROG) method are in good agreement with numerical calculations based on the semiconductor Bloch equations.}}, author = {{Nielsen, N. C. and zu Siederdissen, T. Höner and Kuhl, J. and Schaarschmidt, M. and Förstner, Jens and Knorr, A. and Giessen, H.}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, keywords = {{tet_topic_qd}}, number = {{5}}, publisher = {{American Physical Society (APS)}}, title = {{{Phase Evolution of Solitonlike Optical Pulses during Excitonic Rabi Flopping in a Semiconductor}}}, doi = {{10.1103/physrevlett.94.057406}}, volume = {{94}}, year = {{2005}}, } @inbook{4269, abstract = {{We investigate the spatiotemporal characteristics of subpicosecond pulse propagation in the nonlinear defocusing regime below the band edge of bulk GaAs. We observe temporal and spatial pulse compression and instabilities.}}, author = {{Nielsen, N. C. and zu Höner Siederdissen, T. and Kuhl, J. and Schaarschmidt, M. and Förstner, Jens and Knorr, A. and Koch, S. W. and Giessen, H.}}, booktitle = {{Springer Series in Chemical Physics}}, isbn = {{9783540241102}}, issn = {{0172-6218}}, keywords = {{tet_topic_polariton}}, pages = {{19--21}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Temporal and Spatial Pulse Compression in a Nonlinear Defocusing Material}}}, doi = {{10.1007/3-540-27213-5_5}}, year = {{2005}}, } @article{4270, abstract = {{The adiabatic driving of the resonant electron dynamics in a one-dimensional resonant photonic band gap is proposed as an optical mechanism for nonlinear ultrafast switching. Pulsed excitation inside the photonic gap results in an ultrafast suppression and recovery of the gap. This behavior results from the adiabatic carrier dynamics due to rapid radiative damping inside the band gap.}}, author = {{Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Prineas, John P. and Nielsen, Nils C. and Kuhl, Jürgen and Khitrova, Galina and Gibbs, Hyatt M. and Giessen, Harald and Koch, Stephan W.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{23}}, publisher = {{American Physical Society (APS)}}, title = {{{Adiabatically driven electron dynamics in a resonant photonic band gap: Optical switching of a Bragg periodic semiconductor}}}, doi = {{10.1103/physrevb.70.233302}}, volume = {{70}}, year = {{2004}}, } @article{4274, abstract = {{We present a theory of the optical line shape of coherent intersubband transitions in a semiconductor quantum well, considering non-Markovian LO-phonon scattering as major broadening mechanism. We show that a quantum kinetic approach leads to additional polaron resonances and a resonance enhancement for gap energies close to the phonon energy.}}, author = {{Butscher, S. and Förstner, Jens and Waldmüller, I. and Knorr, A.}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, keywords = {{tet_topic_qw}}, number = {{11}}, pages = {{R49--R51}}, publisher = {{Wiley}}, title = {{{Polaron signatures in the line shape of semiconductor ;intersubband transitions: quantum kinetics of the electron–phonon interaction}}}, doi = {{10.1002/pssb.200409053}}, volume = {{241}}, year = {{2004}}, } @article{4277, abstract = {{We investigate the temporal and spectral properties of subpicosecond pulses transmitted on the heavy-hole exciton transition through a multiple-quantum-well Bragg structure, exhibiting a one-dimensional photonic band gap. At low light intensities, a temporal propagation beating is observed. This beating is strongly dependent on the optical dephasing time T2 which is dominated by the radiative interwell coupling. In an intermediate intensity regime, the Pauli-blocking nonlinearity leads to gradual suppression of the photonic band gap and vanishing of the linear propagation beating. For highly nonlinear excitation, we find signatures of selfinduced transmission due to Rabi flopping and adiabatic following of the carrier density. Numerical simulations using the semiconductor Maxwell-Bloch equations are in excellent agreement with the experimental data up to intensities for which higher many-particle correlations become more important and self-phase modulation occurs in the sample substrate.}}, author = {{Nielsen, N. C. and Kuhl, J. and Schaarschmidt, M. and Förstner, Jens and Knorr, A. and Koch, S. W. and Khitrova, G. and Gibbs, H. M. and Giessen, H.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{7}}, publisher = {{American Physical Society (APS)}}, title = {{{Linear and nonlinear pulse propagation in a multiple-quantum-well photonic crystal}}}, doi = {{10.1103/physrevb.70.075306}}, volume = {{70}}, year = {{2004}}, } @inproceedings{4279, abstract = {{We demonstrate temporal and spatial pulse compression and modulational instabilities in the nonlinear defocusing regime near the band edge of bulk GaAs. Experiment and theory show that spatiotemporal coupling is responsible for these surprising phenomena.}}, author = {{Nielsen, Nils. C. and Siederdissen, Tilmann H. zu and Kuhl, Jürgen and Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Koch, Stephan W. and Giessen, Harald }}, booktitle = {{International Conference on Ultrafast Phenomena 2004}}, isbn = {{3-54024-110-8}}, keywords = {{tet_topic_polariton}}, location = {{Niigata (Japan)}}, publisher = {{Technical Digest (CD) (Optical Society of America, 2004)}}, title = {{{Subpicosecond spatiotemporal pulse compression in a nonlinear defocusing material}}}, year = {{2004}}, } @inproceedings{4280, abstract = {{Theoretically and experimentally, we investigate temporal phase evolution during Rabi-flopping on the A-exciton resonance in CdSe using a novel fast-scanning XFROG method and observe phase changes smaller than π/2 compared to the slightly-chirped input pulse.}}, author = {{Höner zu Siederdissen, Tilman and Nielsen, Nils Christian. and Kuhl, Jürgen and Förstner, Jens and Knorr, Andreas and Giessen, Harald}}, booktitle = {{International Quantum Electronics Conference and Photonic Applications Systems Technologies}}, isbn = {{1-55752-770-9}}, keywords = {{tet_topic_qd}}, location = {{San Francisco, California (USA)}}, publisher = {{OSA}}, title = {{{Temporal phase evolution during excitonic Rabi flopping in semiconductors}}}, doi = {{10.1364/iqec.2004.imb3}}, year = {{2004}}, } @inproceedings{4281, abstract = {{The coupled spatiotemporal characteristics of subpicosecond pulses propagating in the nonlinear defocusing regime near the band edge of bulk GaAs are investigated experimentally and theoretically. We demonstrate pulse compression both in time and transverse space.}}, author = {{Nielsen, Nils C. and Kuhl, Jürgen and Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Koch, Stephan W. and Giessen, Harald }}, booktitle = {{Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies}}, isbn = {{1-55752-770-9}}, keywords = {{tet_topic_polariton}}, location = {{San Francisco, California (USA)}}, publisher = {{Technical Digest (CD) (Optical Society of America, 2004)}}, title = {{{Temporal and spatial compression of near-resonant pulses in a nonlinear defocusing semiconductor }}}, year = {{2004}}, } @inproceedings{4282, abstract = {{We investigate theoretically the ultrafast nonlinear suppression of the resonant photonic band gap by strong laser pulses in semiconductor multiple qnantum wells. We achieve good agreement with our measurements on reflection samples.}}, author = {{Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Prineas, John P. and Nielsen, Nils C. and Kuhl, Jürgen and Kithrova, Galina and Gibbs, Hyatt M. and Giessen, Harald and Koch, Stephan W.}}, booktitle = {{Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies}}, isbn = {{1-55752-778-4 }}, keywords = {{tet_topic_qw}}, location = {{San Francisco, California (USA) }}, publisher = {{OSA}}, title = {{{Nonlinear light pulse propagation in Bragg-periodic multiple semiconductor quantum well samples: ultrafast switching of a resonant photonic band gap}}}, doi = {{10.1364/iqec.2004.iwa3}}, year = {{2004}}, } @inbook{4286, abstract = {{Due to their many-particle character and their application in quantum cascade lasers, optical intersubband excitations in semiconductor quantum wells have become the focus of many recent publications [1,2]. In samples of high quality, intrinsic processes like electron-electron and electron-phonon many particle correlations determine the basic optical and transport properties such as lineshape and ultrafast dynamics. At the same time, intersubband excitations allow the direct investigation of dynamical properties of an important model system of many particle physics - the two-dimensional electron gas. We here present a microscopic theory for the intersubband dynamics and absorption. The calculation of absorption spectra of MQW systems is in principle composed of two parts: the determination of the polarization in a single quantum well within a density matrix approach as the source of electromagnetic radiation (Fig. 1a) and the calculation of the generated fields in the geometry of interest (Fig. 1b) within a Green's function approach [3,4]. We will here focus on the so-called single-pass geometry (cf. Fig. 1b, [5]).}}, author = {{Waldmüller, Ines and Förstner, Jens and Knorr, Andreas }}, booktitle = {{Nonequilibrium Physics at Short Time Scales}}, editor = {{Morawetz, Klaus}}, isbn = {{9783642057458}}, keywords = {{tet_topic_qw}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Self-consistent Projection Operator Theory of Intersubband Absorbance in Semiconductor Quantum Wells}}}, doi = {{10.1007/978-3-662-08990-3}}, year = {{2004}}, } @phdthesis{4319, abstract = {{In dieser Arbeit wird eine Theorie vorgestellt, welche die quantenmechanische Vielteilchenphysik der Licht-Materie Wechselwirkung in Halbleiternanostrukturen beschreibt. Diese mikroskopische Beschreibung wird durch Kombination eines allgemeinen Dichtematrixansatzes mit speziellen Methoden zur Auswertung der Maxwellgleichungen wie der zeitaufgelösten Finite-Differenzen-Methode (FDTD) erreicht. Die Theorie wird auf verschiedene physikalische Situationen angewendet, wie z.B. Lichtausbreitung in Volumenhalbleitern, Interband- und Intersubbandübergänge in Quantenfilmstrukturen und optische Anregung von Quantenpunkten. Der Fokus liegt dabei auf der Beschreibung der linearen und nichtlinearen Antwort des Vielteilchensystems und seiner Ankopplung an das elektromagnetische Feld. In diesem Zusammenhang wird sowohl die Erzeugung als auch der Zerfall von optischen Anregungen untersucht, indem verschiedene Kopplungsmechanismen wie Elektron-Phonon-, Elektron-Photon- und Elektron-Elektron-Wechselwirkung berücksichtigt werden. Im Bereich der linearen Optik, also für Anregung mit geringer Intensität, ermöglicht die Theorie die Berechnung von Absorptionsspektren. Verschiedene Effekte in linearer Optik werden in dieser Arbeit untersucht und beschrieben: Linienaufspaltung durch Polaritonen im Volumenmaterial, Zunahme der Linienbreite bei Intersubbandübergängen verursacht durch Elektron-Elektron- und Elektron- Phonon-Streuung in einzelnen Quantenfilmen, Bildung einer optischen Bandlücke durch starke radiative Kopplung in Vielfilmstrukturen in Bragg-Geometrie, Phononenseitenbänder verursacht durch quantenkinetische Effekte in einzelnen Quantenpunkten und schliesslich Superradianz und Interferenzeffekte in Quantenpunktgittern. Bei nichtlinearer Anregung treten Dichte-Rabiflops als fundamentale Prozesse in allen betrachteten Systemen auf und können als kohärente Be- und Entvölkerung von quantenmechanischen Zuständen beobachtet werden. Der Einfluss von starker Lichtkopplung und verschiedenen Wechselwirkungen auf dynamische Größen wie die Besetzung wird untersucht. Bei nichtlinearer Propagation, bei der sich ein starker Lichtpuls über längere Strecken in einem System bewegt, wird selbstinduzierte Verstärkung der Transmission näher betrachtet. Des weiteren werden von der Coulombwechselwirkung verursachte nichtlineare Effekte wie exzitoninduziertes Dephasieren in Volumenmaterial und verschränkte Zustände in Quantenpunkten untersucht, die einen Zusammenbruch der Hartree-Fock- Näherung darstellen. Zusammenfassend werden in dieser Arbeit verschiedene lineare und nichtlineare optische Effekte in Halbleiternanostrukturen verschiedener Dimensionalität mit Hilfe einer allgemeinen Theorie, die einen Dichtematrixansatz mit den Maxwellschen Gleichungen kombiniert, untersucht.}}, author = {{Förstner, Jens}}, keywords = {{tet_topic_qd, tet_topic_qw, tet_topic_phc}}, title = {{{Light Propagation and Many-Particle Effects in Semiconductor Nanostructures}}}, doi = {{10.14279/depositonce-999}}, year = {{2004}}, }