@article{28196, abstract = {{We show that narrow trenches in a high-contrast silicon-photonics slab can act as lossless power dividers for semi-guided waves. Reflectance and transmittance can be easily configured by selecting the trench width. At sufficiently high angles of incidence, the devices are lossless, apart from material attenuation and scattering due to surface roughness. We numerically simulate a series of devices within the full 0-to-1-range of splitting ratios, for semi-guided plane wave incidence as well as for excitation by focused Gaussian wave bundles. Straightforward cascading of the trenches leads to concepts for 1×M-power dividers and a polarization beam splitter.}}, author = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}}, issn = {{2578-7519}}, journal = {{OSA Continuum}}, keywords = {{tet_topic_waveguide}}, number = {{12}}, pages = {{3081}}, title = {{{Configurable lossless broadband beam splitters for semi-guided waves in integrated silicon photonics}}}, doi = {{10.1364/osac.437549}}, volume = {{4}}, year = {{2021}}, } @article{23843, author = {{Meier, F. and Protte, M. and Baron, E. and Feneberg, M. and Goldhahn, R. and Reuter, Dirk and As, Donat Josef}}, issn = {{2158-3226}}, journal = {{AIP Advances}}, title = {{{Selective area growth of cubic gallium nitride on silicon (001) and 3C-silicon carbide (001)}}}, doi = {{10.1063/5.0053865}}, year = {{2021}}, } @misc{54402, abstract = {{Dataset of the publication “Nondegenerate two-photon absorption in ZnSe: Experiment and theory“, L. Krauss-Kodytek, W.-R. Hannes, T. Meier, C. Ruppert, and M. Betz, Phys. Rev. B 104, 085201 (2021). ( https://doi.org/10.1103/PhysRevB.104.085201 ). The zip file includes the data on which the plots shown in figures 3, 4, and 5 are based.}}, author = {{Krauss-Kodytek, Laura and Hannes, Wolf-Rüdiger and Meier, Torsten and Ruppert, Claudia and Betz, Markus}}, publisher = {{LibreCat University}}, title = {{{Nondegenerate two-photon absorption in ZnSe: Experiment and theory}}}, doi = {{10.5281/ZENODO.5195116}}, year = {{2021}}, } @misc{54401, abstract = {{Dataset of the publication “Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles“, Proc. SPIE 11684,116840X (2021) ( https://doi.org/10.1117/12.2576887 ). The zip file includes the data on which the figures are based, the gnuplot files for the figures, and an explaining readme.txt.}}, author = {{Reichelt, Matthias and Rose, Hendrik and Kosarev, Alexander N. and Poltavtsev, Sergey V. and Bayer, Manfred and Akimov, Ilya A. and Schneider, Christian and Kamp, Martin and Höfling, Sven and Meier, Torsten}}, publisher = {{LibreCat University}}, title = {{{Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles}}}, doi = {{10.5281/ZENODO.5226911}}, year = {{2021}}, } @article{21821, abstract = {{We present a combined experimental and numerical study of the far-field emission properties of optical travelling wave antennas made from low-loss dielectric materials. The antennas considered here are composed of two simple building blocks, a director and a reflector, deposited on a glass substrate. Colloidal quantum dots placed in the feed gap between the two elements serve as internal light source. The emission profile of the antenna is mainly formed by the director while the reflector suppresses backward emission. Systematic studies of the director dimensions as well as variation of antenna material show that the effective refractive index of the director primarily governs the far-field emission pattern. Below cut off, i.e., if the director’s effective refractive index is smaller than the refractive index of the substrate, the main lobe results from leaky wave emission along the director. In contrast, if the director supports a guided mode, the emission predominately originates from the end facet of the director.}}, author = {{Leuteritz, T. and Farheen, Henna and Qiao, S. and Spreyer, F. and Schlickriede, Christian and Zentgraf, Thomas and Myroshnychenko, Viktor and Förstner, Jens and Linden, S.}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_opticalantenna}}, number = {{10}}, title = {{{Dielectric travelling wave antennas for directional light emission}}}, doi = {{10.1364/oe.422984}}, volume = {{29}}, year = {{2021}}, } @article{26889, author = {{Luo, Kai Hong and Santandrea, Matteo and Stefszky, Michael and Sperling, Jan and Massaro, Marcello and Ferreri, Alessandro and Sharapova, Polina and Herrmann, Harald and Silberhorn, Christine}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, title = {{{Quantum optical coherence: From linear to nonlinear interferometers}}}, doi = {{10.1103/physreva.104.043707}}, year = {{2021}}, } @article{26283, author = {{Lüders, Carolin and Pukrop, Matthias and Rozas, Elena and Schneider, Christian and Höfling, Sven and Sperling, Jan and Schumacher, Stefan and Aßmann, Marc}}, issn = {{2691-3399}}, journal = {{PRX Quantum}}, title = {{{Quantifying Quantum Coherence in Polariton Condensates}}}, doi = {{10.1103/prxquantum.2.030320}}, year = {{2021}}, } @article{21946, abstract = {{Lithium niobate (LiNbO3), a material frequently used in optical applications, hosts different kinds of polarons that significantly affect many of its physical properties. In this study, a variety of electron polarons, namely free, bound, and bipolarons, are analyzed using first-principles calculations. We perform a full structural optimization based on density-functional theory for selected intrinsic defects with special attention to the role of symmetry-breaking distortions that lower the total energy. The cations hosting the various polarons relax to a different degree, with a larger relaxation corresponding to a larger gap between the defect level and the conduction-band edge. The projected density of states reveals that the polaron states are formerly empty Nb 4d states lowered into the band gap. Optical absorption spectra are derived within the independent-particle approximation, corrected by the GW approximation that yields a wider band gap and by including excitonic effects within the Bethe-Salpeter equation. Comparing the calculated spectra with the density of states, we find that the defect peak observed in the optical absorption stems from transitions between the defect level and a continuum of empty Nb 4d states. Signatures of polarons are further analyzed in the reflectivity and other experimentally measurable optical coefficients.}}, author = {{Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}}, issn = {{2073-4352}}, journal = {{Crystals}}, pages = {{542}}, publisher = {{MDPI}}, title = {{{Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}}}, doi = {{10.3390/cryst11050542}}, volume = {{11}}, year = {{2021}}, } @article{22310, author = {{Neufeld, Sergej and Bocchini, Adriana and Schmidt, Wolf Gero}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, title = {{{Potassium titanyl phosphate Z- and Y-cut surfaces from density-functional theory}}}, doi = {{10.1103/physrevmaterials.5.064407}}, year = {{2021}}, } @article{22960, abstract = {{We perform a theoretical analysis of the structural and electronic properties of sodium potassium niobate K1-xNaxNbO3 in the orthorhombic room-temperature phase, based on density-functional theory in combination with the supercell approach. Our results for x=0 and x=0.5 are in very good agreement with experimental measurements and establish that the lattice parameters decrease linearly with increasing Na contents, disproving earlier theoretical studies based on the virtual-crystal approximation that claimed a highly nonlinear behavior with a significant structural distortion and volume reduction in K0.5Na0.5NbO3 compared to both end members of the solid solution. Furthermore, we find that the electronic band gap varies very little between x=0 and x=0.5, reflecting the small changes in the lattice parameters.}}, author = {{Bidaraguppe Ramesh, Nithin and Schmidt, Falko and Schindlmayr, Arno}}, issn = {{1434-6036}}, journal = {{The European Physical Journal B}}, number = {{8}}, publisher = {{EDP Sciences, Società Italiana di Fisica and Springer}}, title = {{{Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory}}}, doi = {{10.1140/epjb/s10051-021-00179-8}}, volume = {{94}}, year = {{2021}}, } @article{23816, abstract = {{Employing the ultrafast control of electronic states of a semiconductor quantum dot in a cavity, we introduce an approach to achieve on-demand emission of single photons with almost perfect indistinguishability and photon pairs with near ideal entanglement. Our scheme is based on optical excitation off resonant to a cavity mode followed by ultrafast control of the electronic states using the time-dependent quantum-confined Stark effect, which then allows for cavity-resonant emission. Our theoretical analysis considers cavity-loss mechanisms, the Stark effect, and phonon-induced dephasing, allowing realistic predictions for finite temperatures.}}, author = {{Bauch, David and Heinze, Dirk Florian and Förstner, Jens and Jöns, Klaus and Schumacher, Stefan}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qd}}, pages = {{085308}}, title = {{{Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots}}}, doi = {{10.1103/physrevb.104.085308}}, volume = {{104}}, year = {{2021}}, } @article{23418, abstract = {{Density-functional theory within a Berry-phase formulation of the dynamical polarization is used to determine the second-order susceptibility χ(2) of lithium niobate (LiNbO3). Defect trapped polarons and bipolarons are found to strongly enhance the nonlinear susceptibility of the material, in particular if localized at NbV–VLi defect pairs. This is essentially a consequence of the polaronic excitation resulting in relaxation-induced gap states. The occupation of these levels leads to strongly enhanced χ(2) coefficients and allows for the spatial and transient modification of the second-harmonic generation of macroscopic samples.}}, author = {{Kozub, Agnieszka L. and Schindlmayr, Arno and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{2469-9969}}, journal = {{Physical Review B}}, pages = {{174110}}, publisher = {{American Physical Society}}, title = {{{Polaronic enhancement of second-harmonic generation in lithium niobate}}}, doi = {{10.1103/PhysRevB.104.174110}}, volume = {{104}}, year = {{2021}}, } @article{21547, author = {{Riabinin, Matvei and Sharapova, Polina and Bartley, Tim and Meier, Torsten}}, issn = {{2399-6528}}, journal = {{Journal of Physics Communications}}, number = {{4}}, title = {{{Generating two-mode squeezing with multimode measurement-induced nonlinearity}}}, doi = {{10.1088/2399-6528/abeec2}}, volume = {{5}}, year = {{2021}}, } @inbook{21587, abstract = {{Solving partial differential equations on unstructured grids is a cornerstone of engineering and scientific computing. Nowadays, heterogeneous parallel platforms with CPUs, GPUs, and FPGAs enable energy-efficient and computationally demanding simulations. We developed the HighPerMeshes C++-embedded Domain-Specific Language (DSL) for bridging the abstraction gap between the mathematical and algorithmic formulation of mesh-based algorithms for PDE problems on the one hand and an increasing number of heterogeneous platforms with their different parallel programming and runtime models on the other hand. Thus, the HighPerMeshes DSL aims at higher productivity in the code development process for multiple target platforms. We introduce the concepts as well as the basic structure of the HighPerMeshes DSL, and demonstrate its usage with three examples, a Poisson and monodomain problem, respectively, solved by the continuous finite element method, and the discontinuous Galerkin method for Maxwell’s equation. The mapping of the abstract algorithmic description onto parallel hardware, including distributed memory compute clusters, is presented. Finally, the achievable performance and scalability are demonstrated for a typical example problem on a multi-core CPU cluster.}}, author = {{Alhaddad, Samer and Förstner, Jens and Groth, Stefan and Grünewald, Daniel and Grynko, Yevgen and Hannig, Frank and Kenter, Tobias and Pfreundt, Franz-Josef and Plessl, Christian and Schotte, Merlind and Steinke, Thomas and Teich, Jürgen and Weiser, Martin and Wende, Florian}}, booktitle = {{Euro-Par 2020: Parallel Processing Workshops}}, isbn = {{9783030715922}}, issn = {{0302-9743}}, keywords = {{tet_topic_hpc}}, title = {{{HighPerMeshes – A Domain-Specific Language for Numerical Algorithms on Unstructured Grids}}}, doi = {{10.1007/978-3-030-71593-9_15}}, year = {{2021}}, } @article{21362, author = {{Xue, Yan and Chestnov, Igor and Sedov, Evgeny and Kiktenko, Evgeniy and Fedorov, Aleksey K. and Schumacher, Stefan and Ma, Xuekai and Kavokin, Alexey}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{1}}, title = {{{Split-ring polariton condensates as macroscopic two-level quantum systems}}}, doi = {{10.1103/physrevresearch.3.013099}}, volume = {{3}}, year = {{2021}}, } @article{21359, author = {{Barkhausen, Franziska and Pukrop, Matthias and Schumacher, Stefan and Ma, Xuekai}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{7}}, title = {{{Structuring coflowing and counterflowing currents of polariton condensates in concentric ring-shaped and elliptical potentials}}}, doi = {{10.1103/physrevb.103.075305}}, volume = {{103}}, year = {{2021}}, } @article{29747, author = {{Jurgen von Bardeleben, Hans and Cantin, Jean-Louis and Gerstmann, Uwe and Schmidt, Wolf Gero and Biktagirov, Timur}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}}, number = {{19}}, pages = {{8119--8125}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Spin Polarization, Electron–Phonon Coupling, and Zero-Phonon Line of the NV Center in 3C-SiC}}}, doi = {{10.1021/acs.nanolett.1c02564}}, volume = {{21}}, year = {{2021}}, } @article{22010, author = {{Aldahhak, Hazem and Hogan, Conor and Lindner, Susi and Appelfeller, Stephan and Eisele, Holger and Schmidt, Wolf Gero and Dähne, Mario and Gerstmann, Uwe and Franz, Martin}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, pages = {{035303}}, title = {{{Electronic structure of the Si(111)3×3R30∘−B surface from theory and photoemission spectroscopy}}}, doi = {{10.1103/physrevb.103.035303}}, volume = {{103}}, year = {{2021}}, } @inproceedings{40374, abstract = {{We present a frequency multimode integrated SU (1,1) interferometer with a polarization converter and strong signal-idler photon correlations. Phase sensitivity below the shot noise limit is demonstrated, various filtering and seeding strategies are discussed.}}, author = {{Ferreri, A. and Santandrea, Matteo and Stefszky, Michael and Luo, Kai Hong and Herrmann, Harald and Silberhorn, Christine and Sharapova, Polina}}, booktitle = {{Conference on Lasers and Electro-Optics}}, publisher = {{Optica Publishing Group}}, title = {{{Multimode integrated SU(1,1) interferometer}}}, doi = {{10.1364/cleo_qels.2021.ftu1n.6}}, year = {{2021}}, } @article{58083, author = {{Yaremkevich, Dmytro D. and Scherbakov, Alexey V. and Kukhtaruk, Serhii M. and Linnik, Tetiana L. and Khokhlov, Nikolay E. and Godejohann, Felix and Dyatlova, Olga A. and Nadzeyka, Achim and Pattnaik, Debi P. and Wang, Mu and Roy, Syamashree and Campion, Richard P. and Rushforth, Andrew W. and Gusev, Vitalyi E. and Akimov, Andrey V. and Bayer, Manfred }}, journal = {{ACS Nano}}, number = {{3}}, title = {{{Protected Long-Distance Guiding of Hypersound Underneath a Nanocorrugated Surface}}}, doi = {{10.1021/acsnano.0c09475}}, volume = {{15}}, year = {{2021}}, }