@article{60566,
  author       = {{Bocchini, Adriana and Rüsing, Michael and Bollmers, Laura and Lengeling, Sebastian and Mues, Philipp and Padberg, Laura and Gerstmann, Uwe and Silberhorn, Christine and Eigner, Christof and Schmidt, Wolf Gero}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  number       = {{7}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Mg dopants in lithium niobate: Defect models and impact on domain inversion}}},
  doi          = {{10.1103/5wz1-bjyr}},
  volume       = {{9}},
  year         = {{2025}},
}

@article{58606,
  author       = {{Mathew, Albert and Aschwanden, Rebecca and Tripathi, Aditya and Jangid, Piyush and Sain, Basudeb and Zentgraf, Thomas and Kruk, Sergey}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  keywords     = {{metasurfaces, nanophotonics, nonreciprocity, optical isolators, silicon photonics}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Nonreciprocal Metasurfaces with Epsilon-Near-Zero Materials}}},
  doi          = {{10.1021/acs.nanolett.4c06188}},
  year         = {{2025}},
}

@article{55267,
  author       = {{Schäfer, F. and Trautmann, A. and Ngo, C. and Steiner, J. T. and Fuchs, C. and Volz, K. and Dobener, F. and Stein, M. and Meier, Torsten and Chatterjee, S.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{7}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Optical Stark effect in type-II semiconductor heterostructures}}},
  doi          = {{10.1103/physrevb.109.075301}},
  volume       = {{109}},
  year         = {{2024}},
}

@article{54668,
  abstract     = {{Samples of dielectric optical waveguides of rib or strip type in thin-film lithium niobate (TFLN) technology are characterized with respect to their optical loss using the Fabry-Pérot method. Attributing the losses mainly to sidewall roughness, we employ a simple perturbational procedure, based on rigorously computed mode profiles of idealized channels, to estimate the attenuation for waveguides with different cross sections. A single fit parameter suffices for an adequate modelling of the effect of the waveguide geometry on the loss levels.}},
  author       = {{Hammer, Manfred and Babel, Silia and Farheen, Henna and Padberg, Laura and Scheytt, J. Christoph and Silberhorn, Christine and Förstner, Jens}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{tet_topic_waveguide}},
  number       = {{13}},
  pages        = {{22878}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides}}},
  doi          = {{10.1364/oe.521766}},
  volume       = {{32}},
  year         = {{2024}},
}

@inproceedings{55268,
  author       = {{Rose, Hendrik and Sharapova, Polina R. and Meier, Torsten}},
  booktitle    = {{Ultrafast Phenomena and Nanophotonics XXVIII}},
  editor       = {{Betz, Markus and Elezzabi, Abdulhakem Y.}},
  publisher    = {{SPIE}},
  title        = {{{Microscopic simulations of the dynamics of excitonic many-body correlations coupled to quantum light}}},
  doi          = {{10.1117/12.2690245}},
  year         = {{2024}},
}

@article{55989,
  abstract     = {{Phased arrays are vital in communication systems and have received significant interest in the field of optoelectronics and photonics, enabling a wide range of applications such as LiDAR, holography, wireless communication, etc. In this work, we present a blazed grating antenna that is optimized to have upward radiation efficiency as high as 80% with a compact footprint of 3.5 μm × 2 μm at an operational wavelength of 1.55 μm. Our numerical investigations demonstrate that this antenna in a 64 × 64 phased array configuration is capable of producing desired far-field radiation patterns. Additionally, our antenna possesses a low side lobe level of -9.7 dB and a negligible reflection efficiency of under 1%, making it an attractive candidate for integrated optical phased arrays.}},
  author       = {{Farheen, Henna and Joshi, Suraj and Scheytt, J. Christoph and Myroshnychenko, Viktor and Förstner, Jens}},
  issn         = {{2515-7647}},
  journal      = {{Journal of Physics: Photonics}},
  keywords     = {{tet_topic_opticalantenna}},
  pages        = {{045010}},
  publisher    = {{IOP Publishing}},
  title        = {{{An efficient compact blazed grating antenna for optical phased arrays}}},
  doi          = {{10.1088/2515-7647/ad6ed4}},
  volume       = {{6}},
  year         = {{2024}},
}

@article{56193,
  abstract     = {{Dielectric slab waveguides made of thin-film-lithium-niobate (TFLN) media are consid-ered, for operation in the linear regime. We outline and implement a largely analytic procedure forrigorous modal analysis of three-layer slabs with birefringent, anisotropic core. For Z-cut wave-guides, the slab eigenmode problem separates into uncoupled sets of scalar equations for TE andTM modes. Slabs in X-cut configuration support mostly mildly hybrid eigenmodes, with clear pre-dominant TE or TM polarization, and with effective indices that depend on the propagation directionof the modes, relative to the crystal axes. Strong hybridization can be observed for near degeneratemodes in singular configurations without vertical symmetry, or in symmetric slabs where two nearlydegenerate modes are of the same symmetry class. Dispersion curves for slab thickness and propa-gation angle are discussed, for slabs with oxide and air cover. }},
  author       = {{Hammer, Manfred and Farheen, Henna and Förstner, Jens}},
  issn         = {{2770-0208}},
  journal      = {{Optics Continuum}},
  keywords     = {{tet_topic_waveguide}},
  pages        = {{532822}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Guided modes of thin-film lithium niobate slabs}}},
  doi          = {{10.1364/optcon.532822}},
  year         = {{2024}},
}

@inproceedings{60023,
  author       = {{Wetter, Helene and Gao, Wenlong and Rehberg, Falk and Wingenbach, Jan and Schumacher, Stefan and Zentgraf, Thomas}},
  booktitle    = {{Proceedings of The 14th International Conference on Metamaterials, Photonic Crystals and Plasmonics}},
  issn         = {{2429-1390}},
  location     = {{Toyama, Japan}},
  title        = {{{Dielectric metasurface for wave-vector variant and circular polarization dependent transmission}}},
  year         = {{2024}},
}

@article{57410,
  author       = {{Röder, J. and Gerhard, M. and Fuchs, C. and Stolz, W. and Heimbrodt, W. and Koch, M. and Ngo, C. and Steiner, J. T. and Meier, Torsten}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{19}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Charge transfer magnetoexcitons in magnetoabsorption spectra of asymmetric type-II double quantum wells}}},
  doi          = {{10.1103/physrevb.110.195306}},
  volume       = {{110}},
  year         = {{2024}},
}

@article{61251,
  abstract     = {{<jats:p>We theoretically investigate strategies for the deterministic creation of trains of time-bin entangled photons using an individual quantum emitter described by a Λ-type electronic system. We explicitly demonstrate the theoretical generation of linear cluster states with substantial numbers of entangled photonic qubits in full microscopic numerical simulations. The underlying scheme is based on the manipulation of ground state coherences through precise optical driving. One important finding is that the most easily accessible quality metrics, the achievable rotation fidelities, fall short in assessing the actual quantum correlations of the emitted photons in the face of losses. To address this, we explicitly calculate stabilizer generator expectation values as a superior gauge for the quantum properties of the generated many-photon state. With widespread applicability in other emitter and excitation–emission schemes also, our work lays the conceptual foundations for an in-depth practical analysis of time-bin entanglement based on full numerical simulations with predictive capabilities for realistic systems and setups, including losses and imperfections. The specific results shown in the present work illustrate that with controlled minimization of losses and realistic system parameters for quantum-dot type systems, useful linear cluster states of significant lengths can be generated in the calculations, discussing the possibility of scalability for quantum information processing endeavors.</jats:p>}},
  author       = {{Bauch, David and Köcher, Nikolas and Heinisch, Nils and Schumacher, Stefan}},
  issn         = {{2835-0103}},
  journal      = {{APL Quantum}},
  number       = {{3}},
  publisher    = {{AIP Publishing}},
  title        = {{{Time-bin entanglement in the deterministic generation of linear photonic cluster states}}},
  doi          = {{10.1063/5.0214197}},
  volume       = {{1}},
  year         = {{2024}},
}

@article{61253,
  abstract     = {{<jats:p>In the SUPER scheme (Swing-UP of the quantum EmitteR population), excitation of a quantum emitter is achieved with two off-resonant, red-detuned laser pulses. This allows the generation of high-quality single photons without the need of complex laser stray light suppression or careful spectral filtering. In the present work, we extend this promising method to quantum emitters, specifically semiconductor quantum dots, inside a resonant optical cavity. A significant advantage of the SUPER scheme is identified in that it eliminates re-excitation of the quantum emitter by suppressing photon emission during the excitation cycle. This, in turn, leads to almost ideal single-photon purity, overcoming a major factor typically limiting the quality of photons generated with quantum emitters in high-quality cavities. We further find that for cavity-mediated biexciton emission of degenerate photon pairs, the SUPER scheme leads to near-perfect biexciton initialization with very high values of polarization entanglement of emitted photon pairs.</jats:p>
          <jats:sec>
            <jats:title/>
            <jats:supplementary-material>
              <jats:permissions>
                <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement>
                <jats:copyright-year>2024</jats:copyright-year>
              </jats:permissions>
            </jats:supplementary-material>
          </jats:sec>}},
  author       = {{Heinisch, Nils and Köcher, Nikolas and Bauch, David and Schumacher, Stefan}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{1}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Swing-up dynamics in quantum emitter cavity systems: Near ideal single photons and entangled photon pairs}}},
  doi          = {{10.1103/physrevresearch.6.l012017}},
  volume       = {{6}},
  year         = {{2024}},
}

@article{61255,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>Topological states have been widely investigated in different types of systems and lattices. In the present work, we report on topological edge states in double-wave (DW) chains, which can be described by a generalized Aubry-André-Harper (AAH) model. For the specific system of a driven-dissipative exciton polariton system we show that in such potential chains, different types of edge states can form. For resonant optical excitation, we further find that the optical nonlinearity leads to a multistability of different edge states. This includes topologically protected edge states evolved directly from individual linear eigenstates as well as additional edge states that originate from nonlinearity-induced localization of bulk states. Extending the system into two dimensions (2D) by stacking horizontal DW chains in the vertical direction, we also create 2D multi-wave lattices. In such 2D lattices multiple Su–Schrieffer–Heeger (SSH) chains appear along the vertical direction. The combination of DW chains in the horizonal and SSH chains in the vertical direction then results in the formation of higher-order topological insulator corner states. Multistable corner states emerge in the nonlinear regime.</jats:p>}},
  author       = {{Schneider, Tobias and Gao, Wenlong and Zentgraf, Thomas and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{2192-8614}},
  journal      = {{Nanophotonics}},
  number       = {{4}},
  pages        = {{509--518}},
  publisher    = {{Walter de Gruyter GmbH}},
  title        = {{{Topological edge and corner states in coupled wave lattices in nonlinear polariton condensates}}},
  doi          = {{10.1515/nanoph-2023-0556}},
  volume       = {{13}},
  year         = {{2024}},
}

@article{61257,
  abstract     = {{<jats:p>Exceptional points (EPs), with their intriguing spectral topology, have attracted considerable attention in a broad range of physical systems, with potential sensing applications driving much of the present research in this field. Here, we investigate spectral topology and EPs in systems with significant nonlinearity, exemplified by a nonequilibrium exciton-polariton condensate. With the possibility to control loss and gain and nonlinearity by optical means, this system allows for a comprehensive analysis of the interplay of nonlinearities (Kerr type and saturable gain) and non-Hermiticity. Not only do we find that EPs can be intentionally shifted in parameter space by the saturable gain, but we also observe intriguing rotations and intersections of Riemann surfaces and find nonlinearity-enhanced sensing capabilities. With this, our results illustrate the potential of tailoring spectral topology and related phenomena in non-Hermitian systems by nonlinearity.</jats:p>
          <jats:sec>
            <jats:title/>
            <jats:supplementary-material>
              <jats:permissions>
                <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement>
                <jats:copyright-year>2024</jats:copyright-year>
              </jats:permissions>
            </jats:supplementary-material>
          </jats:sec>}},
  author       = {{Wingenbach, Jan and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{1}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Manipulating spectral topology and exceptional points by nonlinearity in non-Hermitian polariton systems}}},
  doi          = {{10.1103/physrevresearch.6.013148}},
  volume       = {{6}},
  year         = {{2024}},
}

@article{61357,
  author       = {{Krenz, Marvin and Sanna, Simone and Gerstmann, Uwe and Schmidt, Wolf Gero}},
  issn         = {{1932-7447}},
  journal      = {{The Journal of Physical Chemistry C}},
  number       = {{41}},
  pages        = {{17774--17778}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Understanding and Improving Triplet Exciton Transfer in Sensitized Silicon Solar Cells}}},
  doi          = {{10.1021/acs.jpcc.4c05446}},
  volume       = {{128}},
  year         = {{2024}},
}

@inbook{62916,
  author       = {{Zhang, Hongdan and Zuo, Ruixin and Yang, Shidong and Trautmann, Alexander and Song, Xiaohong and Meier, Torsten and Yang, Weifeng}},
  booktitle    = {{High-Order Harmonic Generation in Solids}},
  isbn         = {{9789811279553}},
  publisher    = {{WORLD SCIENTIFIC}},
  title        = {{{Analyzing High-Order Harmonic Generation in Solids Based on Semi-Classical Recollision Models}}},
  doi          = {{10.1142/9789811279560_0006}},
  year         = {{2024}},
}

@inbook{62917,
  author       = {{Reichelt, Matthias and Zuo, Ruixin and Song, Xiaohong and Yang, Weifeng and Meier, Torsten}},
  booktitle    = {{High-Order Harmonic Generation in Solids}},
  isbn         = {{9789811279553}},
  publisher    = {{WORLD SCIENTIFIC}},
  title        = {{{High-Order Harmonic Generation in Semiconductors with Excitonic Effects}}},
  doi          = {{10.1142/9789811279560_0009}},
  year         = {{2024}},
}

@article{60581,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>The natural band alignments between indium phosphide and the main dioxides of titanium, i.e. rutile, anatase, and brookite as well as amorphous titania are calculated from the branch-point energies of the respective materials. Irrespective of the titania polymorph considered, type-I band alignment is predicted. This may change, however, in dependence on the microscopic interface structure: supercell calculations for amorphous titania grown on P-rich InP(001) surfaces result in a titania conduction band that nearly aligns with that of InP. Depending on the interface specifics, both type-I band and type-II band alignments are observed in the simulations. This agrees with recent experimental findings.</jats:p>}},
  author       = {{Ruiz Alvarado, Isaac Azahel and Dreßler, Christian and Schmidt, Wolf Gero}},
  issn         = {{0953-8984}},
  journal      = {{Journal of Physics: Condensed Matter}},
  number       = {{7}},
  publisher    = {{IOP Publishing}},
  title        = {{{Band alignment at InP/TiO<sub>2</sub> interfaces from density-functional theory}}},
  doi          = {{10.1088/1361-648x/ad9725}},
  volume       = {{37}},
  year         = {{2024}},
}

@article{54868,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Most properties of solid materials are defined by their internal electric field and charge density distributions which so far are difficult to measure with high spatial resolution. Especially for 2D materials, the atomic electric fields influence the optoelectronic properties. In this study, the atomic‐scale electric field and charge density distribution of WSe<jats:sub>2</jats:sub> bi‐ and trilayers are revealed using an emerging microscopy technique, differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). For pristine material, a higher positive charge density located at the selenium atomic columns compared to the tungsten atomic columns is obtained and tentatively explained by a coherent scattering effect. Furthermore, the change in the electric field distribution induced by a missing selenium atomic column is investigated. A characteristic electric field distribution in the vicinity of the defect with locally reduced magnitudes compared to the pristine lattice is observed. This effect is accompanied by a considerable inward relaxation of the surrounding lattice, which according to first principles DFT calculation is fully compatible with a missing column of Se atoms. This shows that DPC imaging, as an electric field sensitive technique, provides additional and remarkable information to the otherwise only structural analysis obtained with conventional STEM imaging.</jats:p>}},
  author       = {{Groll, Maja and Bürger, Julius and Caltzidis, Ioannis and Jöns, Klaus D. and Schmidt, Wolf Gero and Gerstmann, Uwe and Lindner, Jörg K. N.}},
  issn         = {{1613-6810}},
  journal      = {{Small}},
  publisher    = {{Wiley}},
  title        = {{{DFT‐Assisted Investigation of the Electric Field and Charge Density Distribution of Pristine and Defective 2D WSe<sub>2</sub> by Differential Phase Contrast Imaging}}},
  doi          = {{10.1002/smll.202311635}},
  year         = {{2024}},
}

@article{54856,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>Theoretical spectroscopy based on double perturbation theory is typically challenged by systems with large orbital hyperfine splitting. Therefore, we here derive a rigorous, non-perturbative scheme starting from Dirac’s equation which allows to calculate the contribution of the orbital HFI for complex structures including heavy atoms with strong spin-orbit coupling (SOC). Using the PAW formalism, the method has been implemented in the software package Quantum ESPRESSO. We show that the ‘orbital part’ actually scales with SOC strength if orbital quenching is hindered by low local symmetry, i.e. in case of dimers or atoms at surfaces. This holds true in particular when the unpaired electron is localized in quasi-atomic <jats:italic>p</jats:italic>-like orbitals. Here, the orbital part is by far not negligible, but becomes dominant by surpassing the dipolar contribution by a factor of five.</jats:p>}},
  author       = {{Franzke, Katharina and Schmidt, Wolf Gero and Gerstmann, Uwe}},
  issn         = {{1742-6588}},
  journal      = {{Journal of Physics: Conference Series}},
  number       = {{1}},
  publisher    = {{IOP Publishing}},
  title        = {{{Relativistic calculation of the orbital hyperfine splitting in complex microscopic structures}}},
  doi          = {{10.1088/1742-6596/2701/1/012094}},
  volume       = {{2701}},
  year         = {{2024}},
}

@article{54865,
  author       = {{Krenz, Marvin and Gerstmann, Uwe and Schmidt, Wolf Gero}},
  issn         = {{0031-9007}},
  journal      = {{Physical Review Letters}},
  number       = {{7}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Defect-Assisted Exciton Transfer across the Tetracene-Si(111):H Interface}}},
  doi          = {{10.1103/physrevlett.132.076201}},
  volume       = {{132}},
  year         = {{2024}},
}