@article{43285, author = {{Meier, Torsten and Thomas, P.}}, journal = {{Physik Journal}}, number = {{3}}, pages = {{53--59}}, title = {{{Echos in Festkörpern}}}, volume = {{2}}, year = {{2003}}, } @inbook{43273, author = {{Meier, Torsten and Pasenow, B. and Thomas, P. and Koch, S.W.}}, booktitle = {{Germany NIC Series, Vol. 20}}, editor = {{Wolf, Dietrich and Münster, Gernot and Kremer, Manfred}}, isbn = {{3-00-012372-5}}, pages = {{261--270}}, publisher = {{John von Neumann Institute for Computing}}, title = {{{Many-body Coulomb effects in the optical properties of semiconductor heterostructures}}}, volume = {{20}}, year = {{2003}}, } @article{4310, abstract = {{Nonlinear propagation of optical pulses through an extended bulk semiconductor is investigated using the coupled semiconductor Maxwell‐Bloch equations including excitation induced correlations. For short pulse excitation around the exciton resonance, the theory describes the development of polariton beats and their suppression at increasing input pulse intensities due to the coupling of single exciton states to the Coulomb‐correlated continuum of two‐exciton states. A comparison of the theoretical results with experimental observations for CdSe bulk material is presented.}}, author = {{Förstner, Jens and Knorr, A. and Kuckenburg, S. and Meier, Torsten and Koch, S.W. and Giessen, H. and Linden, S. and Kuhl, J.}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, keywords = {{tet_topic_polariton}}, number = {{1}}, pages = {{453--457}}, publisher = {{Wiley}}, title = {{{Nonlinear Polariton Pulse Propagation in Bulk Semiconductors}}}, doi = {{10.1002/1521-3951(200009)221:1<453::aid-pssb453>3.0.co;2-q}}, volume = {{221}}, year = {{2002}}, } @article{43294, abstract = {{The quantum dynamics of an ensemble of interacting electrons in an array of random scatterers is treated using a numerical approach for the calculation of average values of quantum operators and time correlation functions in the Wigner representation. The Fourier transform of the product of matrix elements of the dynamic propagators obeys an integral Wigner-Liouville-type equation. Initial conditions for this equation are given by the Fourier transform of the Wiener path-integral representation of the matrix elements of the propagators at the chosen initial times. This approach combines both molecular dynamics and Monte Carlo methods and computes numerical traces and spectra of the relevant dynamical quantities such as momentum-momentum correlation functions and spatial dispersions. Considering, as an application, a system with fixed scatterers, the results clearly demonstrate that the many-particle interaction between the electrons leads to an enhancement of the conductivity and spatial dispersion compared to the noninteracting case.}}, author = {{Meier, Torsten and Filinov, V. and Thomas, P. and Varga, I. and Bonitz, M. and Fortov, V. and Koch, S.W.}}, journal = {{Physical Review B}}, number = {{16}}, publisher = {{American Physical Society}}, title = {{{Interacting electrons in a one-dimensional random array of scatterers: A quantum dynamics and Monte Carlo study}}}, doi = {{10.1103/PhysRevB.65.165124}}, volume = {{65}}, year = {{2002}}, } @article{43295, abstract = {{The influence of coherent photoexcited excitons on the absorption spectra and the Four Wave Mixing response of ZnSe/ZnMgSSe quantum wells is investigated for various polarization configurations. For purely resonant excitation at the heavy-hole-exciton a blue shift and an increasing homogeneous line width of the exciton absorption peak is found. The clear and stable blue shift shows a linear dependence on excitation fluence both in experiment and theory with different slopes for the different pump and probe polarization configurations. The equivalence of pump and probe, and Four Wave Mixing results is shown experimentally.}}, author = {{Meier, Torsten and Wachter, S. and Maute, M. and Kalt, H. and Galbraith, I. and Sieh, C. and Koch, S.W.}}, journal = {{Physica B: Condensed Matter}}, number = {{1-4}}, pages = {{309--313}}, publisher = {{North-Holland}}, title = {{{Excitation induced shift and broadening of the exciton resonance}}}, doi = {{10.1016/S0921-4526(01)01400-4}}, volume = {{314}}, year = {{2002}}, } @article{43292, abstract = {{Physicists have realized during the last two decades that the physical properties of many condensed-matter systems are often best described in terms of lumps of charge, known as quasiparticles, rather than by electrons and ions. In a crystal under equlibrium conditions, for example, the mutual repulsion of the electrons leads to a cloud of positive charge surrounding each individual electron. This "dressing" of electrons leads to charge screening. In other words, a test charge placed far from an electron will feel the influence of a new entity with a smaller charge, rather than the charge on the "bare" electron.}}, author = {{Meier, Torsten and Koch, S.W.}}, journal = {{Physics World}}, number = {{2}}, pages = {{24--25}}, publisher = {{IOP Publishing}}, title = {{{Particles get all dressed up}}}, doi = {{10.1088/2058-7058/15/2/36}}, volume = {{15}}, year = {{2002}}, } @article{43291, abstract = {{On the basis of a tight-binding model for a strongly disordered semiconductor with correlated conduction- and valence-band disorder a coherent dynamical intraband effect is analyzed. For systems that are excited by two specially designed ultrashort light-pulse sequences delayed by τ relatively to each other echolike phenomena are predicted to occur. In addition to the interband photon echo which shows up at exactly t=2τ relative to the first pulse, the system responds with two spontaneous intraband current pulses preceding and following the appearance of the photon echo. The temporal splitting depends on the electron-hole mass ratio. Calculating the population relaxation rate due to Coulomb scattering, it is concluded that the predicted new dynamical effect should be experimentally observable in an interacting and strongly disordered system, such as the Quantum Coulomb Glass.}}, author = {{Meier, Torsten and Schlichenmaier, C. and Varga, I. and Thomas, P. and Koch, S.W.}}, journal = {{Physical Review B}}, number = {{8}}, publisher = {{American Physical Society}}, title = {{{Optically induced coherent intraband dynamics in disordered semiconductors}}}, doi = {{10.1103/PhysRevB.65.085306}}, volume = {{65}}, year = {{2002}}, } @inproceedings{44127, abstract = {{A microscopic theory for optical semiconductor nonlinearities systematically including Coulomb correlation effects is able to explain AC Stark shifts measured with all possible pump/probe circular polarizations and gives evidence for a 3-level-atom-like intervalence band coherence.}}, author = {{Meier, Torsten and Gibbs, H.M. and Khitrova, G. and Ell, C. and Binder, R. and Hoyer, W. and Kira, M. and Koch, S.W. and Sieh, C.}}, booktitle = {{Nonlinear Optics: Materials, Fundamentals and Applications}}, isbn = {{1-55752-721-0}}, location = {{Wailea, Maui, Hawaii United States}}, publisher = {{Optical Society of America}}, title = {{{Higher-Order Correlations and Semiconductor Optical Nonlinearities}}}, doi = {{10.1364/NLO.2002.WA1}}, year = {{2002}}, } @article{43293, abstract = {{We present a derivation of Förster coupling between two quantum dots by solving the equation of motion for the material excitation simultaneously with Maxwells equations. This allows us to identify the Förster process with the short-range contribution of the coupling that is mediated by the total electric field. The dependence of the coupling on the distance R of the dots is ∝ R—3, i.e. the rates follow the well-known R—6 behaviour. For distances between the sites longer than a quarter of the wavelength of light there is a cross-over to coupling due to the retarded light field, which is ∝ R—1, i.e. the rates are ∝ R—2.}}, author = {{Meier, Torsten and Thomas, P. and Möller, M. and Eichmann, R. and Stroucken, T. and Knorr, A.}}, journal = {{physica status solidi (b)}}, number = {{1}}, pages = {{25--29}}, publisher = {{WILEY‐VCH Verlag Berlin GmbH}}, title = {{{Microscopic Foundation of the Förster Excitonic Energy Transfer Process}}}, doi = {{10.1002/1521-3951(200203)230:1<25::AID-PSSB25>3.0.CO;2-8}}, volume = {{230}}, year = {{2002}}, } @article{43297, abstract = {{A microscopic many-body theory describing the optical and electronic properties of semiconductors and semiconductor nanostructures is briefly reviewed. At the semiclassical level, the optical response is computed using Maxwell's equations together with the semiconductor Bloch equations which describe the dynamics of the diagonal and the off-diagonal terms of the reduced single-particle density matrix. These equations include the coupling between the semiconductor and the optical field as well as Coulomb many-body interactions among the optically excited carriers. Under quasi-equilibrium conditions, luminescence spectra can be obtained from absorption spectra on the basis of the Kubo–Martin–Schwinger relation for conditions usually limited to the regime of optical gain (lasers). More generally, light emission has to be computed at a fully quantum mechanical level leading to semiconductor luminescence equations.}}, author = {{Meier, Torsten and Koch, S.W. and Hoyer, W. and Kira, M.}}, journal = {{Physica E: Low-Dimensional Systems and Nanostructures}}, number = {{1-2}}, pages = {{45--52}}, publisher = {{North-Holland}}, title = {{{Theory of the optical properties of semiconductor nanostructures}}}, doi = {{10.1016/S1386-9477(02)00358-2}}, volume = {{14}}, year = {{2002}}, } @article{43296, abstract = {{A three-beam configuration is used to investigate the spectrally resolved wave-mixing signal of a ZnSe single quantum well. The spectrum recorded in direction 2 k2–k1 shows coherent oscillations induced by a delayed third pulse with direction k3. Intensity and polarization-dependent measurements indicate that the signal is generated by a combination of four- and six-wave mixing. The origin of the oscillations can be explained qualitatively by a two-level model. The polarization-dependent experimental results require the treatment of many-body correlations and are well explained by microscopic calculations including four-particle correlations up to fifth order in the fields.}}, author = {{Meier, Torsten and Wagner, H.P. and Tranitz, H.-P. and Reichelt, Matthias and Koch, S.W.}}, journal = {{physica status solidi (a)}}, number = {{3}}, pages = {{843--847}}, publisher = {{WILEY‐VCH Verlag Berlin GmbH}}, title = {{{Coherent Oscillations in Multiwave Mixing Due to Higher‐Order Coulomb Correlations}}}, doi = {{10.1002/1521-396X(200204)190:3<843::AID-PSSA843>3.0.CO;2-B}}, volume = {{190}}, year = {{2002}}, } @article{43300, abstract = {{The influence of coupling, correlation, and disorder on exciton and biexciton signatures is investigated using coherent excitation spectroscopy. Different biexciton-induced transitions of a single biexciton state are spectrally resolved. One of the transitions is found to be particularly sensitive to disorder. Mixed biexciton resonances, resulting from attractively interacting heavy and light hole exciton states, are identified. The observations are analyzed on the basis of microscopic model calculations.}}, author = {{Meier, Torsten and Finger, E. and Kraft, S.P. and Hofmann, M. and Koch, S.W. and Stolz, W. and Rühle, W.W.}}, journal = {{physica status solidi (b)}}, number = {{1}}, pages = {{424--434}}, publisher = {{WILEY‐VCH Verlag}}, title = {{{Coulomb correlations and biexciton signatures in coherent excitation spectroscopy of semiconductor quantum wells}}}, doi = {{10.1002/1521-3951(200211)234:1<424::AID-PSSB424>3.0.CO;2-V}}, volume = {{234}}, year = {{2002}}, } @inbook{43298, author = {{Meier, Torsten and Reichelt, Matthias and Schlichenmaier, C. and Siggelkow, S. and Thomas, P. and Koch, S.W. and Weiser, S. and Sieh, C.}}, booktitle = {{Germany NIC Series Vol. 9}}, editor = {{Rollnik, Horst and Wolf, Dietrich}}, isbn = {{3-00-009055-X}}, pages = {{ 315--324}}, publisher = {{John von Neumann Institute for Computing}}, title = {{{Many-Body Correlation Effects in Photoexcited Semiconductor Heterostructures}}}, year = {{2002}}, } @article{43299, abstract = {{A density-matrix theory for absorption changes in semiconductors induced by electron or hole occupations is outlined. Bound and unbound trions are included via four-point correlation functions representing electron–hole pair transitions in the presence of carrier populations. The spectra calculated for semiconductor nanorings show bleaching of the exciton resonance and induced absorption at energies corresponding to transitions to bound and unbound trion states. Without a magnetic field, induced absorption below the exciton line due to bound negatively (positively) charged trions appears when the two electrons (holes) of the trion are in different bands. A magnetic field introduces characteristic modifications of the spectra that can be attributed to the Aharonov–Bohm effect. It may lead to the formation of additional bound magneto-trion states.}}, author = {{Meier, Torsten and Thomas, P. and Koch, S.W. and Maschke, K.}}, journal = {{physica status solidi (b)}}, number = {{1}}, pages = {{283--293}}, publisher = {{WILEY‐VCH Verlag}}, title = {{{Signatures of trions in the optical spectra of doped semiconductor nanorings in a magnetic field}}}, doi = {{10.1002/1521-3951(200211)234:1<283::AID-PSSB283>3.0.CO;2-J}}, volume = {{234}}, year = {{2002}}, } @article{43301, author = {{Meier, Torsten and Koch, S.W.}}, journal = {{Physik Journal}}, number = {{12}}, pages = {{41--48}}, publisher = {{WILEY-VCH}}, title = {{{Optodynamik}}}, volume = {{1}}, year = {{2002}}, } @inbook{43303, abstract = {{This chapter focuses on the carrier interaction effects—that is, the many-body Coulomb correlations and their influence on band-gap semiconductor optical nonlinearities. The near band-gap semiconductor response is determined by the optical interaction with the resonant or near resonant material polarization that may result in the excitation of carriers (electron–hole pairs) and/or transient coherent nonlinearities. The microscopic analysis of these effects requires the investigation of the relevant quasi-particles and their interactions. Whereas the basic occurrence of a blue shift can be motivated already based on a simple two-level model, a more detailed understanding of the optical Stark effect in semiconductors requires a microscopic modeling of the relevant bands as well as the inclusion of the many-body Coulomb interaction. Compensations among the first- and higher-order Coulomb terms at the spectral positions of the exciton are obtained in the differential absorption induced by incoherent occupations.}}, author = {{Meier, Torsten and Koch, S.W.}}, booktitle = {{Ultrafast Physical Processes in Semiconductors}}, editor = {{Tsen, K.T.}}, isbn = {{978-0-12-752176-3}}, pages = {{231--313}}, publisher = {{Elsevier}}, title = {{{Coulomb correlation signatures in the excitonic optical nonlinearities of semiconductors}}}, doi = {{10.1016/S0080-8784(01)80172-1}}, volume = {{67}}, year = {{2001}}, } @article{43307, abstract = {{The influence of fifth-order coherences on the spectrally resolved four-wave mixing response of predominantly homogeneously broadened quasi-two-dimensional excitons is studied. Fifth-order signatures are discussed as a function of spectral position and excitation polarization. An exciton–biexciton beating for positive delay times is the dominant effect, which is pronounced at the exciton–biexciton transition for collinearly polarized excitation and at the exciton transition for cross-linearly polarized excitation. For negative delay times and collinearly polarized excitation a pronounced exciton–biexciton beating at the exciton resonance is observed that is vanishing for long negative delays owing to the faster dephasing in the two-exciton continuum compared with the bound biexciton state. These results are in qualitative agreement with microscopic model calculations that include the coherent dynamics of one- and two-exciton resonances up to the fifth order in the optical field.}}, author = {{Meier, Torsten and Langbein, W. and Koch, S.W. and Hvam, J.M.}}, journal = {{Journal of the Optical Society of America B}}, number = {{9}}, pages = {{1318--1325}}, publisher = {{Optical Society of America}}, title = {{{Spectral signatures of χ(5) processes in four-wave mixing of homogeneously broadened excitons}}}, doi = {{10.1364/JOSAB.18.001318}}, volume = {{18}}, year = {{2001}}, } @article{43306, abstract = {{Linear and nonlinear optical absorption spectra are studied theoretically for semiconductor nanorings penetrated by a magnetic field. Due to the Aharanov-Bohm effect the spectral position as well as the oscillator strength of the exciton change periodically as function of the magnetic flux enclosed by the ring. In the nonlinear differential absorption spectra it is found that the magnetic field strongly modifies Coulomb many-body correlations. In particular, the magnetic-field-induced increase of the exciton binding energy is accompanied by a decrease of the biexciton binding energy. The persistence of these effects in the presence of energetic disorder is analyzed.}}, author = {{Meier, Torsten and Thomas, P. and Koch, S.W.}}, journal = {{The European Physical Journal B - Condensed Matter and Complex Systems}}, pages = {{249--256}}, publisher = {{EDP sciences}}, title = {{{Linear and nonlinear optical properties of semiconductor nanorings with magnetic field and disorder-Influence on excitons and biexcitons}}}, doi = {{10.1007/s100510170133}}, volume = {{22}}, year = {{2001}}, } @inbook{43302, abstract = {{In this chapter a microscopic many-body theory is reviewed that allows one to compute the linear and nonlinear optical properties of semiconductor superlattices in the presence of homogeneous electric fields applied in the growth direction. The theory includes the process of optical excitation, the Coulomb interaction among the carriers, carrier-phonon coupling, and the acceleration induced by the electric field. Coherent phenomena induced by dc and ac fields, like Bloch oscillations and dynamical localization, are introduced and discussed. The theoretical analysis concentrates on the signatures and observability of such phenomena in linear and nonlinear optical experiments.}}, author = {{Meier, Torsten and Thomas, P. and Koch, S.W.}}, booktitle = {{Ultrafast Phenomena in Semiconductors}}, editor = {{Tsen, K.T.}}, isbn = {{978-1-4612-6562-7}}, pages = {{1--92}}, publisher = {{Springer}}, title = {{{Coherent Dynamics of Photoexcited Semiconductor Superlattices with Applied Homogeneous Electric Fields}}}, doi = {{10.1007/978-1-4613-0203-2_1}}, year = {{2001}}, } @article{43305, abstract = {{Pump-probe experiments on high-quality InxGa1−x As quantum wells are used to investigate the influence of light-hole excitons on the optical Stark effect. For anticircular polarization of pump and probe pulses and a moderate negative detuning of the pump energy, a redshift of the heavy-hole resonance is observed. However, with increasingly negative detuning a transition from this redshift to a blueshift is found. Microscopic calculations that include both heavy holes and light holes reproduce the experimental results. The theoretical analysis shows that the observation of the redshift depends very sensitively on the detuning of the pump pulses and the heavy-hole to light-hole splitting.}}, author = {{Meier, Torsten and Brick, P. and Ell, C. and Khitrova, G. and Gibbs, H.M. and Sieh, C. and Koch, S.W.}}, journal = {{Physical Review B}}, number = {{7}}, publisher = {{American Physical Society}}, title = {{{Influence of Light Holes on the Heavy-Hole Excitonic Optical Stark Effect}}}, doi = {{10.1103/PhysRevB.64.075323}}, volume = {{64}}, year = {{2001}}, }