TY - JOUR AU - Plaickner, Julian AU - Speiser, Eugen AU - Braun, Christian AU - Schmidt, Wolf Gero AU - Esser, Norbert AU - Sanna, Simone ID - 22008 JF - Physical Review B SN - 2469-9950 TI - Surface localized phonon modes at the Si(553)-Au nanowire system ER - TY - JOUR AU - Meier, Lukas AU - Schmidt, Wolf Gero ID - 40244 IS - 1 JF - physica status solidi (b) KW - Condensed Matter Physics KW - Electronic KW - Optical and Magnetic Materials SN - 0370-1972 TI - GaInP/AlInP(001) Interfaces from Density Functional Theory VL - 259 ER - TY - JOUR AU - Ruiz Alvarado, Isaac Azahel AU - Karmo, Marsel AU - Runge, Erich AU - Schmidt, Wolf Gero ID - 22009 JF - ACS Omega SN - 2470-1343 TI - InP and AlInP(001)(2 × 4) Surface Oxidation from Density Functional Theory ER - TY - JOUR AB - 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. AU - Bidaraguppe Ramesh, Nithin AU - Schmidt, Falko AU - Schindlmayr, Arno ID - 22960 IS - 8 JF - The European Physical Journal B SN - 1434-6028 TI - Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory VL - 94 ER - TY - JOUR AU - Friedrich, Christoph AU - Blügel, Stefan AU - Schindlmayr, Arno ID - 22761 IS - 3 JF - Physical Review B SN - 2469-9950 TI - Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)] VL - 104 ER - TY - JOUR AB - Uniaxial anisotropy in nonlinear birefringent crystals limits the efficiency of nonlinear optical interactions and breaks the spatial symmetry of light generated in the parametric down-conversion (PDC) process. Therefore, this effect is usually undesirable and must be compensated for. However, high gain may be used to overcome the destructive role of anisotropy in order to generate bright two-mode correlated twin-beams. In this work, we provide a rigorous theoretical description of the spatial properties of bright squeezed light in the presence of strong anisotropy. We investigate a single crystal and a system of two crystals with an air gap (corresponding to a nonlinear SU(1,1) interferometer) and demonstrate the generation of bright correlated twin-beams in such configurations at high gain due to anisotropy. We explore the mode structure of the generated light and show how anisotropy, together with crystal spacing, can be used for radiation shaping. AU - Riabinin, M. AU - Sharapova, Polina AU - Meier, Torsten ID - 37334 IS - 14 JF - Optics Express KW - Atomic and Molecular Physics KW - and Optics SN - 1094-4087 TI - Bright correlated twin-beam generation and radiation shaping in high-gain parametric down-conversion with anisotropy VL - 29 ER - TY - JOUR AU - Geraldi, Andrea AU - De, Syamsundar AU - Laneve, Alessandro AU - Barkhofen, Sonja AU - Sperling, Jan AU - Mataloni, Paolo AU - Silberhorn, Christine ID - 26287 JF - Physical Review Research SN - 2643-1564 TI - Transient subdiffusion via disordered quantum walks ER - TY - JOUR AU - Tiedau, J. AU - Engelkemeier, M. AU - Brecht, Benjamin AU - Sperling, Jan AU - Silberhorn, Christine ID - 21021 JF - Physical Review Letters SN - 0031-9007 TI - Statistical Benchmarking of Scalable Photonic Quantum Systems VL - 126 ER - TY - JOUR AU - Prasannan, Nidhin AU - De, Syamsundar AU - Barkhofen, Sonja AU - Brecht, Benjamin AU - Silberhorn, Christine AU - Sperling, Jan ID - 26286 JF - Physical Review A SN - 2469-9926 TI - Experimental entanglement characterization of two-rebit states VL - 103 ER - TY - JOUR AU - Köhnke, S. AU - Agudelo, E. AU - Schünemann, M. AU - Schlettwein, O. AU - Vogel, W. AU - Sperling, Jan AU - Hage, B. ID - 26285 JF - Physical Review Letters SN - 0031-9007 TI - Quantum Correlations beyond Entanglement and Discord ER - TY - JOUR AB - 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. AU - Bauch, David AU - Heinze, Dirk Florian AU - Förstner, Jens AU - Jöns, Klaus AU - Schumacher, Stefan ID - 23816 JF - Physical Review B KW - tet_topic_qd SN - 2469-9950 TI - Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots VL - 104 ER - TY - JOUR AB - AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands. AU - Wiebeler, Christian AU - Vollbrecht, Joachim AU - Neuba, Adam AU - Kitzerow, Heinz-Siegfried AU - Schumacher, Stefan ID - 39653 IS - 1 JF - Scientific Reports KW - Multidisciplinary SN - 2045-2322 TI - Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters VL - 11 ER - TY - JOUR AU - Klement, Philip AU - Dehnhardt, Natalie AU - Dong, Chuan-Ding AU - Dobener, Florian AU - Bayliff, Samuel AU - Winkler, Julius AU - Hofmann, Detlev M. AU - Klar, Peter J. AU - Schumacher, Stefan AU - Chatterjee, Sangam AU - Heine, Johanna ID - 40434 IS - 23 JF - Advanced Materials KW - Mechanical Engineering KW - Mechanics of Materials KW - General Materials Science SN - 0935-9648 TI - Atomically Thin Sheets of Lead‐Free 1D Hybrid Perovskites Feature Tunable White‐Light Emission from Self‐Trapped Excitons VL - 33 ER - TY - JOUR AU - Barkhausen, Franziska AU - Pukrop, Matthias AU - Schumacher, Stefan AU - Ma, Xuekai ID - 21359 IS - 7 JF - Physical Review B SN - 2469-9950 TI - Structuring coflowing and counterflowing currents of polariton condensates in concentric ring-shaped and elliptical potentials VL - 103 ER - TY - JOUR AU - Franz, Martin AU - Chandola, Sandhya AU - Koy, Maximilian AU - Zielinski, Robert AU - Aldahhak, Hazem AU - Das, Mowpriya AU - Freitag, Matthias AU - Gerstmann, Uwe AU - Liebig, Denise AU - Hoffmann, Adrian Karl AU - Rosin, Maximilian AU - Schmidt, Wolf Gero AU - Hogan, Conor AU - Glorius, Frank AU - Esser, Norbert AU - Dähne, Mario ID - 24975 JF - Nature Chemistry SN - 1755-4330 TI - Controlled growth of ordered monolayers of N-heterocyclic carbenes on silicon ER - TY - JOUR AB - 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. AU - Kozub, Agnieszka L. AU - Schindlmayr, Arno AU - Gerstmann, Uwe AU - Schmidt, Wolf Gero ID - 23418 JF - Physical Review B SN - 2469-9950 TI - Polaronic enhancement of second-harmonic generation in lithium niobate VL - 104 ER - TY - CONF AU - Rose, Hendrik AU - Paul, Jagannath AU - Wahlstrand, Jared K. AU - Bristow, Alan D. AU - Meier, Torsten ED - Betz, Markus ED - Elezzabi, Abdulhakem Y. ID - 23475 T2 - Ultrafast Phenomena and Nanophotonics XXV TI - Theoretical analysis and simulations of two-dimensional Fourier transform spectroscopy performed on exciton-polaritons of a quantum-well microcavity system VL - 11684 ER - TY - JOUR AU - Krauss-Kodytek, L. AU - Hannes, W.-R. AU - Meier, Torsten AU - Ruppert, C. AU - Betz, M. ID - 37333 IS - 8 JF - Physical Review B SN - 2469-9950 TI - Nondegenerate two-photon absorption in ZnSe: Experiment and theory VL - 104 ER - TY - JOUR AU - Riabinin, Matvei AU - Sharapova, Polina AU - Bartley, Tim AU - Meier, Torsten ID - 21547 IS - 4 JF - Journal of Physics Communications SN - 2399-6528 TI - Generating two-mode squeezing with multimode measurement-induced nonlinearity VL - 5 ER - TY - JOUR AU - Krauss-Kodytek, L. AU - Hannes, Wolf-Rüdiger AU - Meier, Torsten AU - Ruppert, C. AU - Betz, M. ID - 23472 IS - 8 JF - Physical Review B SN - 2469-9950 TI - Nondegenerate two-photon absorption in ZnSe: Experiment and theory VL - 104 ER -