@inproceedings{3543, author = {{Hildebrandt, Andre and Alhaddad, Samer and Hammer, Manfred and Förstner, Jens}}, booktitle = {{Integrated Optics: Devices, Materials, and Technologies XX}}, editor = {{Broquin, Jean-Emmanuel and Nunzi Conti, Gualtiero}}, keywords = {{tet_topic_waveguide}}, publisher = {{SPIE}}, title = {{{Oblique incidence of semi-guided waves on step-like folds in planar dielectric slabs: Lossless vertical interconnects in 3D integrated photonic circuits}}}, doi = {{10.1117/12.2214460}}, year = {{2016}}, } @article{13920, abstract = {{We investigate the transient optical response in high-quality Cd0.88Zn0.12Te crystals in the regime of slow light propagation on the lower exciton-polariton branch. Femtosecond photoexcitation leads to very substantial transmission changes in a ∼10-meV broad spectral range within the transparency window of the unexcited semiconductor. These nonlinear optical signatures decay on picosecond time scales governed by carrier thermalization and recombination. The temporal and spectral dependence indicate the dynamical optical response as arising from excitation-induced dephasing and perturbed free induction decay. Model simulations for the optical response taking into account the actual exciton-polariton dispersion and excitation-induced dephasing of a nonlinearly driven two-level system support this interpretation.}}, author = {{Lohrenz, J. and Melzer, S. and Ruppert, C. and Akimov, I. A. and Mariette, H. and Reichelt, Matthias and Trautmann, Alexander and Meier, Torsten and Betz, M.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{7}}, title = {{{Ultrafast dynamical response of the lower exciton-polariton branch in CdZnTe}}}, doi = {{10.1103/physrevb.93.075201}}, volume = {{93}}, year = {{2016}}, } @article{10024, abstract = {{The influence of electronic many-body interactions, spin-orbit coupling, and thermal lattice vibrations on the electronic structure of lithium niobate is calculated from first principles. Self-energy calculations in the GW approximation show that the inclusion of self-consistency in the Green function G and the screened Coulomb potential W opens the band gap far stronger than found in previous G0W0 calculations but slightly overestimates its actual value due to the neglect of excitonic effects in W. A realistic frozen-lattice band gap of about 5.9 eV is obtained by combining hybrid density functional theory with the QSGW0 scheme. The renormalization of the band gap due to electron-phonon coupling, derived here using molecular dynamics as well as density functional perturbation theory, reduces this value by about 0.5 eV at room temperature. Spin-orbit coupling does not noticeably modify the fundamental gap but gives rise to a Rashba-like spin texture in the conduction band.}}, author = {{Riefer, Arthur and Friedrich, Michael and Sanna, Simone and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}}, issn = {{2469-9969}}, journal = {{Physical Review B}}, number = {{7}}, publisher = {{American Physical Society}}, title = {{{LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects}}}, doi = {{10.1103/PhysRevB.93.075205}}, volume = {{93}}, year = {{2016}}, } @article{10025, abstract = {{The phonon dispersions of the ferro‐ and paraelectric phase of LiTaO3 are calculated within density‐functional perturbation theory. The longitudinal optical phonon modes are theoretically derived and compared with available experimental data. Our results confirm the recent phonon assignment proposed by Margueron et al. [J. Appl. Phys. 111, 104105 (2012)] on the basis of spectroscopical studies. A comparison with the phonon band structure of the related material LiNbO3 shows minor differences that can be traced to the atomic‐mass difference between Ta and Nb. The presence of phonons with imaginary frequencies for the paraelectric phase suggests that it does not correspond to a minimum energy structure, and is compatible with an order‐disorder type phase transition.}}, author = {{Friedrich, Michael and Schindlmayr, Arno and Schmidt, Wolf Gero and Sanna, Simone}}, issn = {{1521-3951}}, journal = {{Physica Status Solidi B}}, number = {{4}}, pages = {{683--689}}, publisher = {{Wiley-VCH}}, title = {{{LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles}}}, doi = {{10.1002/pssb.201552576}}, volume = {{253}}, year = {{2016}}, } @article{13910, author = {{Ma, Xuekai and Driben, Rodislav and Malomed, Boris A. and Meier, Torsten and Schumacher, Stefan}}, issn = {{2045-2322}}, journal = {{Scientific Reports}}, title = {{{Two-dimensional symbiotic solitons and vortices in binary condensates with attractive cross-species interaction}}}, doi = {{10.1038/srep34847}}, volume = {{6}}, year = {{2016}}, } @article{4185, abstract = {{Semiconductor quantum-dot cavity systems are promising sources for solid-state-based on-demand generation of single photons for quantum communication. Commonly, the spectral characteristics of the emitted single photon are fixed by system properties such as electronic transition energies and spectral properties of the cavity. In the present work we study cavity-enhanced single-photon generation from the quantum-dot biexciton through a partly stimulated nondegenerate two-photon emission. We show that frequency and linewidth of the single photon can be fully controlled by the stimulating laser pulse, ultimately allowing for efficient all-optical spectral shaping of the single photon.}}, author = {{Breddermann, D. and Heinze, D. and Binder, R. and Zrenner, Artur and Schumacher, Stefan}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{16}}, publisher = {{American Physical Society (APS)}}, title = {{{All-optical tailoring of single-photon spectra in a quantum-dot microcavity system}}}, doi = {{10.1103/physrevb.94.165310}}, volume = {{94}}, year = {{2016}}, } @article{13919, author = {{Sternemann, E. and Jostmeier, T. and Ruppert, C. and Thunich, S. and Duc, H. T. and Podzimski, R. and Meier, Torsten and Betz, M.}}, issn = {{0946-2171}}, journal = {{Applied Physics B}}, title = {{{Quantum interference control of electrical currents in GaAs microstructures: physics and spectroscopic applications}}}, doi = {{10.1007/s00340-015-6310-y}}, volume = {{122}}, year = {{2016}}, } @article{10030, abstract = {{The vibrational properties of stoichiometric LiNbO3 are analyzed within density-functional perturbation theory in order to obtain the complete phonon dispersion of the material. The phonon density of states of the ferroelectric (paraelectric) phase shows two (one) distinct band gaps separating the high-frequency (~800 cm−1) optical branches from the continuum of acoustic and lower optical phonon states. This result leads to specific heat capacites in close agreement with experimental measurements in the range 0–350 K and a Debye temperature of 574 K. The calculated zero-point renormalization of the electronic Kohn–Sham eigenvalues reveals a strong dependence on the phonon wave vectors, especially near Γ. Integrated over all phonon modes, our results indicate a vibrational correction of the electronic band gap of 0.41 eV at 0 K, which is in excellent agreement with the extrapolated temperature-dependent measurements.}}, author = {{Friedrich, Michael and Riefer, Arthur and Sanna, Simone and Schmidt, Wolf Gero and Schindlmayr, Arno}}, issn = {{1361-648X}}, journal = {{Journal of Physics: Condensed Matter}}, number = {{38}}, publisher = {{IOP Publishing}}, title = {{{Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory}}}, doi = {{10.1088/0953-8984/27/38/385402}}, volume = {{27}}, year = {{2015}}, } @article{13504, author = {{Sanna, S. and Dues, C. and Schmidt, Wolf Gero}}, issn = {{0927-0256}}, journal = {{Computational Materials Science}}, pages = {{145--150}}, title = {{{Modeling atomic force microscopy at LiNbO 3 surfaces from first-principles}}}, doi = {{10.1016/j.commatsci.2015.03.025}}, volume = {{103}}, year = {{2015}}, } @article{13506, author = {{Sanson, A. and Zaltron, A. and Argiolas, N. and Sada, C. and Bazzan, M. and Schmidt, Wolf Gero and Sanna, S.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, title = {{{Polaronic deformation at theFe2+/3+impurity site inFe:LiNbO3crystals}}}, doi = {{10.1103/physrevb.91.094109}}, volume = {{91}}, year = {{2015}}, } @article{13507, author = {{Landmann, M. and Rauls, E. and Schmidt, Wolf Gero and Neumann, M. D. and Speiser, E. and Esser, N.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, title = {{{GaNm-plane: Atomic structure, surface bands, and optical response}}}, doi = {{10.1103/physrevb.91.035302}}, volume = {{91}}, year = {{2015}}, } @article{4330, abstract = {{Sources of single photons are key elements for applications in quantum information science. Among the different sources available, semiconductor quantum dots excel with their integrability in semiconductor on-chip solutions and the potential that photon emission can be triggered on demand. Usually, the photon is emitted from a single-exciton ground state. Polarization of the photon and time of emission are either probabilistic or pre-determined by electronic properties of the system. Here, we study the direct two-photon emission from the biexciton. The two-photon emission is enabled by a laser pulse driving the system into a virtual state inside the band gap. From this intermediate state, the single photon of interest is then spontaneously emitted. We show that emission through this higher-order transition provides a versatile approach to generate a single photon. Through the driving laser pulse, polarization state, frequency and emission time of the photon can be controlled on-the-fly.}}, author = {{Heinze, Dirk and Breddermann, Dominik and Zrenner, Artur and Schumacher, Stefan}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, number = {{1}}, publisher = {{Springer Nature}}, title = {{{A quantum dot single-photon source with on-the-fly all-optical polarization control and timed emission}}}, doi = {{10.1038/ncomms9473}}, volume = {{6}}, year = {{2015}}, } @article{8762, author = {{Sergent, S. and Kako, S. and Bürger, M. and Schupp, T. and As, Donat Josef and Arakawa, Y.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, title = {{{Polarization properties of single zinc-blende GaN/AlN quantum dots}}}, doi = {{10.1103/physrevb.90.235312}}, year = {{2014}}, } @article{10036, author = {{Hölscher, Rebecca and Schmidt, Wolf Gero and Sanna, Simone}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{10213--10220}}, title = {{{Modeling LiNbO3 Surfaces at Ambient Conditions}}}, doi = {{10.1021/jp502936f}}, year = {{2014}}, } @article{13514, author = {{Li, Yanlu and Schmidt, Wolf Gero and Sanna, S.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{9}}, title = {{{IntrinsicLiNbO3point defects from hybrid density functional calculations}}}, doi = {{10.1103/physrevb.89.094111}}, volume = {{89}}, year = {{2014}}, } @article{13515, author = {{Sanna, S. and Hölscher, R. and Schmidt, Wolf Gero}}, issn = {{0169-4332}}, journal = {{Applied Surface Science}}, pages = {{70--78}}, title = {{{Temperature dependent LiNbO3(0001): Surface reconstruction and surface charge}}}, doi = {{10.1016/j.apsusc.2014.01.104}}, year = {{2014}}, }