@article{60001, author = {{Zietlow, Christian and Lindner, Jörg}}, journal = {{Ultramicroscopy}}, number = {{275}}, publisher = {{Elsevier}}, title = {{{An unbiased ADMM-TGV algorithm for the deconvolution of STEM-EELS maps}}}, doi = {{10.1016/j.ultramic.2025.114159}}, year = {{2025}}, } @phdthesis{63856, abstract = {{Electron energy-loss spectroscopy (EELS) is an advanced analytical technique in transmission electron microscopy, as it provides insights into material characteristics, such as electronic properties or elemental composition, at the atomic scale. The precision of every EELS analysis, however, is inherently limited by noises and blur. This thesis offers a comprehensive understanding of the noise, which is particularly valuable at low dwell times necessary for beam sensitive materials and for electron-matter interactions with low frequency of occurrence, where the noise dominates the measurement. Additionally, correlations encountered in the noise of an EELS measurement are described from both a theoretical and experimental perspective. These correlations are caused by a convolution of the noisy signal with the detector point spread function. Methods for characterizing key noise parameters of typical detectors are described, allowing the noise model to be tailored to any EELS detector. Ultimately, a novel deconvolution method enabling significant sharpening and denoising of EELS measurements is introduced and demonstrated. Its efficiency is further validated on both simulation and experimental data. The described advancement offered by the proposed deconvolution method enables the extension of current electron microscope capabilities, facilitating analysis that would be unfeasible with existing deconvolution techniques.}}, author = {{Zietlow, Christian}}, publisher = {{Universitätsbibliothek Paderborn}}, title = {{{A novel Lagrangian-based method for the deconvolution of electron energy-loss spectra}}}, doi = {{10.17619/UNIPB/1-2438}}, year = {{2025}}, } @article{63882, author = {{Dinkelbach, Lars and Wudy, Stefan A. and Hartmann, Michaela F. and Libuda, Lars and Föcker, Manuel and Hebebrand, Johannes and Hinney, Anke and Nöthlings, Ute and Alexy, Ute and Grasemann, Corinna and Hirtz, Raphael}}, issn = {{0165-0327}}, journal = {{Journal of Affective Disorders}}, publisher = {{Elsevier BV}}, title = {{{Urinary steroid metabolome shows adrenal, gonadal, and neuroactive steroid dysregulation in adolescents with depressive symptoms}}}, doi = {{10.1016/j.jad.2025.120867}}, volume = {{399}}, year = {{2025}}, } @unpublished{64071, abstract = {{Stimulated by the renewed interest and recent developments in semi-empirical quantum chemical (SQC) methods for noncovalent interactions, we examine the properties of liquid water at ambient conditions by means of molecular dynamics (MD) simulations, both with the conventional NDDO-type (neglect of diatomic differential overlap) methods, e.g. AM1 and PM6, and with DFTB-type (density-functional tight-binding) methods, e.g. DFTB2 and GFN-xTB. Besides the original parameter sets, some specifically reparametrized SQC methods (denoted as AM1-W, PM6-fm, and DFTB2-iBi) targeting various smaller water systems ranging from molecular clusters to bulk are considered as well. The quality of these different SQC methods for describing liquid water properties at ambient conditions are assessed by comparison to well-established experimental data and also to BLYP-D3 density functional theory-based ab initio MD simulations. Our analyses reveal that static and dynamics properties of bulk water are poorly described by all considered SQC methods with the original parameters, regardless of the underlying theoretical models, with most of the methods suffering from too weak hydrogen bonds and hence predicting a far too fluid water with highly distorted hydrogen bond kinetics. On the other hand, the reparametrized force-matchcd PM6-fm method is shown to be able to quantitatively reproduce the static and dynamic features of liquid water, and thus can be used as a computationally efficient alternative to electronic structure-based MD simulations for liquid water that requires extended length and time scales. DFTB2-iBi predicts a slightly overstructured water with reduced fluidity, whereas AM1-W gives an amorphous ice-like structure for water at ambient conditions.}}, author = {{Wu, Xin and Elgabarty, Hossam and Alizadeh, Vahideh and Henao Aristizabal, Andres and Zysk, Frederik and Plessl, Christian and Ehlert, Sebastian and Hutter, Jürg and Kühne, Thomas D.}}, title = {{{Benchmarking semi-empirical quantum chemical methods on liquid water}}}, year = {{2025}}, } @article{63745, abstract = {{Multimode squeezed light is an increasingly popular tool in photonic quantum technologies, including sensing, imaging, and computation. Meanwhile, the existing methods of its characterization are technically complicated, which reduces the level of squeezing, and mostly deal with a single mode at a time. Here, for the first time, to the best of our knowledge, we employ optical parametric amplification to characterize multiple squeezing eigenmodes simultaneously. We retrieve the shapes and squeezing degrees of all modes at once through direct detection followed by modal decomposition. This method is tolerant to inefficient detection and does not require a local oscillator. For a spectrally and spatially multimode squeezed vacuum, we characterize eight strongest spatial modes, obtaining squeezing and anti-squeezing values of up to −5.2 ± 0.2 dB and 8.6 ± 0.3 dB, respectively, despite the 50% detection loss. This work, being the first exploration of an optical parametric amplifier’s multimode capability for squeezing detection, paves the way for the real-time detection of multimode squeezing.}}, author = {{Barakat, Ismail and Kalash, Mahmoud and Scharwald, Dennis and Sharapova, Polina and Lindlein, Norbert and Chekhova, Maria}}, issn = {{2837-6714}}, journal = {{Optica Quantum}}, number = {{1}}, publisher = {{Optica Publishing Group}}, title = {{{Simultaneous measurement of multimode squeezing through multimode phase-sensitive amplification}}}, doi = {{10.1364/opticaq.524682}}, volume = {{3}}, year = {{2025}}, } @article{64662, abstract = {{ In this study, we investigate the impact of chromium-induced point defects on the nonlinear optical properties and electric-field-induced second harmonic generation (EFISH) in rutile titanium dioxide (TiO 2 ). Chromium thin films were deposited by electron beam evaporation on (001)-oriented bulk TiO 2 substrates and subsequently diffused into the lattice in a tube furnace under a nitrogen atmosphere at 900 °C. The introduction of chromium significantly enhanced the third harmonic generation (THG) of a 1560 nm laser, with an amplification factor of up to 8.3, indicative of an enhanced third-order nonlinear susceptibility, χ (3) . Moreover, the application of an external voltage induced a pronounced EFISH signal in the chromium-doped samples, further confirming the enhanced nonlinear response. These results demonstrate that defect engineering via chromium doping in rutile TiO 2 offers a promising pathway for the development of high-performance nonlinear optical devices. }}, author = {{Brinkmann, Marius and Meier, Falco and Spedt, Vladimir and Meier, Cedrik}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{26}}, publisher = {{Optica Publishing Group}}, title = {{{Boosting third-order nonlinearities in rutile TiO2 by chromium doping}}}, doi = {{10.1364/oe.572063}}, volume = {{33}}, year = {{2025}}, } @article{61241, abstract = {{Abstract Given the presence of fake news and pseudoscience (often disguised as physics), the importance of inoculating citizens against this type of misinformation has gained increasing attention in education. This is a goal that all subjects should pursue equally from their respective disciplinary perspectives. 
The paper presents a teaching approach to protect physics students from misinformation and pseudoscience by combining these three common strategies: First, understanding the fundamental principles of the Nature of Science. Second, identifying techniques of Science Denial. And third, applying heuristics for evaluating (supposedly) scientific information. Finally, the paper offers practical suggestions for applying these strategies in a master's-level physics course, using examples from the field of physics.}}, author = {{Webersen, Yvonne and Riese, Josef}}, issn = {{0143-0807}}, journal = {{European Journal of Physics}}, publisher = {{IOP Publishing}}, title = {{{Protecting physics students from pseudoscience - combining strategies for a comprehensive teaching approach}}}, doi = {{10.1088/1361-6404/ae03f6}}, year = {{2025}}, } @article{61245, author = {{Barkhausen, Franziska and Ares Santos, Laura and Schumacher, Stefan and Sperling, Jan}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{3}}, publisher = {{American Physical Society (APS)}}, title = {{{Entanglement between dependent degrees of freedom: Quasiparticle correlations}}}, doi = {{10.1103/physreva.111.032404}}, volume = {{111}}, year = {{2025}}, } @article{61246, abstract = {{Abstract The time-dependent one-dimensional nonlinear Schrödinger equation (NLSE) is solved numerically by a hybrid pseudospectral-variational quantum algorithm that connects a pseudospectral step for the Hamiltonian term with a variational step for the nonlinear term. The Hamiltonian term is treated as an integrating factor by forward and backward Fourier transforms, which are here carried out classically. This split allows us to avoid higher-order time integration schemes, to apply a first-order explicit time stepping for the remaining nonlinear NLSE term in a variational algorithm block, and thus to avoid numerical instabilities. We demonstrate that the analytical solution is reproduced with a small root mean square error for a long time interval over which a nonlinear soliton propagates significantly forward in space while keeping its shape. We analyze the accuracy and complexity of the quantum algorithm, the expressibility of the ansatz circuit and compare it with classical approaches. Furthermore, we investigate the influence of algorithm parameters on the accuracy of the results, including the temporal step width and the depth of the quantum circuit.}}, author = {{Köcher, Nikolas and Rose, Hendrik and Bharadwaj, Sachin S. and Schumacher, Jörg and Schumacher, Stefan}}, issn = {{2045-2322}}, journal = {{Scientific Reports}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Numerical solution of nonlinear Schrödinger equation by a hybrid pseudospectral-variational quantum algorithm}}}, doi = {{10.1038/s41598-025-05660-3}}, volume = {{15}}, year = {{2025}}, } @article{61249, author = {{Ai, Qiang and Wingenbach, Jan and Yang, Xinmiao and Wei, Jing and Hatzopoulos, Zaharias and Savvidis, Pavlos G. and Schumacher, Stefan and Ma, Xuekai and Gao, Tingge}}, issn = {{2331-7019}}, journal = {{Physical Review Applied}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Optically and remotely controlling localization of exciton-polariton condensates in a potential lattice}}}, doi = {{10.1103/physrevapplied.23.024029}}, volume = {{23}}, year = {{2025}}, } @article{61338, abstract = {{Conductive ferroelectric domain walls (DWs) represent a promising topical system for the development of nanoelectronic components and device sensors to be operational at elevated temperatures. DWs show very different properties as compared to their hosting bulk crystal, in particular with respect to the high local electrical conductivity. The objective of this work is to demonstrate DW conductivity up to temperatures as high as 400 °C which extends previous studies significantly. Experimental investigation of the DW conductivity of charged, inclined DWs is performed using 5 mol % MgO-doped lithium niobate single crystals. Current–voltage ( ) curves are determined by DC electrometer measurements and impedance spectroscopy and found to be identical. Moreover, impedance spectroscopy enables to recognize artifacts such as damaged electrodes. Temperature dependent measurements over repeated heating cycles reveal two distinct thermal activation energies for a given DW, with the higher of the activation energies only measured at higher temperatures. Depending on the specific sample, the higher activation energy is found above 160 °C to 230 °C. This suggests, in turn, that more than one type of defect/polaron is involved, and that the dominant transport mechanism changes with increasing temperature. First principles atomistic modeling suggests that the conductivity of inclined domain walls cannot be solely explained by the formation of a 2D carrier gas and must be supported by hopping processes. This holds true even at temperatures as high as 400 °C. Our investigations underline the potential to extend DW current based nanoelectronic and sensor applications even into the so-far unexplored temperature range up to 400 °C.}}, author = {{Wulfmeier, Hendrik and Yakhnevych, Uliana and Boekhoff, Cornelius and Diima, Allan and Kunzner, Marlo and Verhoff, Leonard M. and Paul, Jonas and Ratzenberger, Julius and Beyreuther, Elke and Gössel, Joshua and Kiseleva, Iuliia and Rüsing, Michael and Sanna, Simone and Eng, Lukas M. and Fritze, Holger}}, issn = {{0167-2738}}, journal = {{Solid State Ionics}}, publisher = {{Elsevier BV}}, title = {{{Demonstration of domain wall current in MgO-doped lithium niobate single crystals up to 400°C}}}, doi = {{10.1016/j.ssi.2025.116949}}, volume = {{429}}, year = {{2025}}, } @article{61337, abstract = {{Lithium niobate–tantalate mixed (LNT) crystals promise improved performance and new applications for optical, piezomechanical, or electrical devices when compared to the end composition compounds lithium niobate and lithium tantalate. The macroscopic properties of ferroelectrics highly depend on the structure of the underlying ferroelectric domains, which within mixed crystals can interact with the local changes in chemical compositions. In this work, we demonstrate how ferroelectric domain walls can unambiguously be identified and distinguished from local changes in composition by correlating piezoresponse force microscopy with second harmonic generation microscopy, using the Cherenkov contrast, reference crystal contrast, and negative phase mismatching contrast. We demonstrate how measuring the associated intensity change when approaching negative phase mismatching can be used to deduce the local tantalum concentration fast and over a large sample area. Based on these results, we study the natural domain structures that appear from Czochralski-grown, multi-domain LNT solid solution crystals. The developed results and methods serve as the central foundation to poling these mixed crystal systems and are key for their integration and applications.}}, author = {{Koppitz, Boris and Saxena, Tanya and Bernhardt, Felix and Ganschow, Steffen and Sanna, Simone and Rüsing, Michael and Eng, Lukas M.}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, number = {{3}}, publisher = {{AIP Publishing}}, title = {{{Second harmonic generation contrasts of ferroelectric domain structures and composition in lithium niobate–tantalate mixed crystals}}}, doi = {{10.1063/5.0276183}}, volume = {{138}}, year = {{2025}}, } @article{61351, abstract = {{AbstractThe interaction of water molecules with semiconductor surfaces is relevant to various optoelectronic phenomena and physicochemical processes. Despite advances in fundamental understanding of water‐exposed surfaces, the detailed time‐ and energy‐resolved behavior of excited electrons remains largely unexplored. Here, the effects of water exposure on the near‐surface electron dynamics of phosphorus‐terminated p(2×2)/c(4×2)‐reconstructed indium phosphide (100) (P‐rich InP) are studied experimentally and matched to theoretical calculations. The P‐rich InP surface, consisting of H‐passivated P‐dimers, serves as a model for other P‐containing III‐V semiconductors such as gallium phosphide (GaP) or aluminum indium phosphide (AlInP). Electron dynamics near the surface are probed with femtosecond resolution using time‐resolved two‐photon photoemission (tr‐2PPE), a pump‐probe spectroscopic technique. Pulsed water exposure preserves electronic states and significantly increases lifetimes at the conduction band minimum (CBM). Density‐functional theory (DFT) calculations attribute these findings to suppression of surface vibrational modes in the top P‐layer by water exposure, reducing electronic transition probabilities of near‐band‐gap surface states. The results suggest that many near‐surface state lifetimes reported in ultra‐high vacuum may change significantly upon electrolyte exposure. These states may thus contribute more strongly to surface reactions than traditionally assumed. Demonstrating this effect for the technologically relevant P‐rich InP surface opens new opportunities in this underexplored area of surface electrochemistry.}}, author = {{Diederich, Jonathan and Paszuk, Agnieszka and Ruiz Alvarado, Isaac Azahel and Krenz, Marvin and Zare Pour, Mohammad Amin and Babu, Diwakar Suresh and Velazquez Rojas, Jennifer and Höhn, Christian and Gao, Yuying and Schwarzburg, Klaus and Ostheimer, David and Eichberger, Rainer and Schmidt, Wolf Gero and Hannappel, Thomas and de Krol, Roel van and Friedrich, Dennis}}, issn = {{2196-7350}}, journal = {{Advanced Materials Interfaces}}, number = {{16}}, publisher = {{Wiley}}, title = {{{Ultrafast Electron Dynamics at the Water‐Modified InP(100) Surface}}}, doi = {{10.1002/admi.202500463}}, volume = {{12}}, year = {{2025}}, } @article{61356, abstract = {{First-principles calculations reveal how topological defects in semiconducting carbon nanotubes trap triplet excitons and enable single-photon emission at telecom wavelengths, offering new insights into their potential for photonic devices.}}, author = {{Biktagirov, Timur and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{2040-3364}}, journal = {{Nanoscale}}, number = {{11}}, pages = {{6884--6891}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Topological defects in semiconducting carbon nanotubes as triplet exciton traps and single-photon emitters}}}, doi = {{10.1039/d4nr03904a}}, volume = {{17}}, year = {{2025}}, } @article{58519, abstract = {{A unified theoretical approach to describe the properties of multimode squeezed light generated in a lossy medium is presented. This approach is valid for Markovian environments and includes both a model of discrete losses based on the beamsplitter approach and a generalized continuous loss model based on the spatial Langevin equation. For an important class of Gaussian states, we derive master equations for the second-order correlation functions and illustrate their solution for both frequency-independent and frequency-dependent losses. Studying the mode structure, we demonstrate that in a lossy environment no broadband basis without quadrature correlations between the different broadband modes exists. Therefore, various techniques and strategies to introduce broadband modes can be considered. We show that the Mercer expansion and the Williamson-Euler decomposition do not provide modes in which the maximal squeezing contained in the system can be measured. In turn, we find a new broadband basis that maximizes squeezing in the lossy system and present an algorithm to construct it.}}, author = {{Kopylov, Denis A. and Meier, Torsten and Sharapova, Polina R.}}, issn = {{2521-327X}}, journal = {{Quantum}}, publisher = {{Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften}}, title = {{{Theory of Multimode Squeezed Light Generation in Lossy Media}}}, doi = {{10.22331/q-2025-02-04-1621}}, volume = {{9}}, year = {{2025}}, } @inbook{61394, author = {{Satzinger, Nicole and Fögen, Yvonne and Noetzel, Ida and Kehne, Miriam}}, booktitle = {{Handbuch Bewegung und Sport in der Sozialen Arbeit}}, editor = {{Matzner, Michael and Wojciechowski, Torsten}}, pages = {{507--512}}, publisher = {{Beltz Juventa}}, title = {{{"FiBSS - Fortschritt in und durch Bewegung, Spiel und Sport im Grundschulganztag" - eine Qualifizierung für das pädagogische Personal im Ganztag}}}, year = {{2025}}, } @inbook{61393, author = {{Kehne, Miriam and Fögen, Yvonne and Satzinger, Nicole and Noetzel, Ida}}, booktitle = {{Handbuch Bewegung und Sport in der Sozialen Arbeit}}, editor = {{Matzner, Michael and Wojciechowski, Torsten }}, pages = {{261--272}}, publisher = {{Beltz Juventa}}, title = {{{Bewegung und Sport in der Ganztagsschule}}}, year = {{2025}}, } @article{61279, abstract = {{Spin waves represent an important class of low-energy excitations in magnetic solids, which influence the thermodynamic properties and play a major role in technical applications, such as spintronics or magnetic data storage. Despite the enormous advances of ab initio simulations in materials science, quantitative calculations of spin-wave spectra still pose a significant challenge, because the collective nature of the spin dynamics requires an accurate treatment of the Coulomb interaction between the electrons. As a consequence, simple lattice models like the Heisenberg Hamiltonian are still widespread in practical investigations, but modern techniques like time-dependent density-functional theory or many-body perturbation theory also open a route to material-specific spin-wave calculations from first principles. Although both are in principle exact, actual implementations necessarily employ approximations for electronic exchange and correlation as well as additional numerical simplifications. In this review, we recapitulate the theoretical foundations of ab initio spin-wave calculations and analyze the common approximations that underlie present implementations. In addition, we survey the available results for spin-wave dispersions of various magnetic materials and compare the performance of different computational approaches. In this way, we provide an overview of the present state of the art and identify directions for further developments.}}, author = {{Neugum, Michael and Schindlmayr, Arno}}, issn = {{1996-1944}}, journal = {{Materials}}, number = {{18}}, publisher = {{MDPI}}, title = {{{Ab initio calculations of spin waves: A review of theoretical approaches and applications}}}, doi = {{10.3390/ma18184431}}, volume = {{18}}, year = {{2025}}, } @article{60959, abstract = {{Miller's rule originated as an empirical relation between the nonlinear and linear optical coefficients of materials. It is now accepted as a useful tool for guiding experiments and computational materials discovery, but its theoretical foundation had long been limited to a derivation for the classical Lorentz model with a weak anharmonic perturbation. Recently, we developed a mathematical framework which enabled us to prove that Miller's rule is equally valid for quantum anharmonic oscillators, despite different dynamics due to zero-point fluctuations and further quantum-mechanical effects. However, our previous derivation applied only to one-dimensional oscillators and to the special case of second- and third-harmonic generation in a monochromatic electric field. Here we extend the proof to three-dimensional quantum anharmonic oscillators and also treat all orders of the nonlinear response to an arbitrary multi-frequency field. This makes the results applicable to a much larger range of physical systems and nonlinear optical processes. The obtained generalized Miller formulae rigorously express all tensor elements of the frequency-dependent nonlinear susceptibilities in terms of the linear susceptibility and thus allow a computationally inexpensive quantitative prediction of arbitrary parametric frequency-mixing processes from a small initial dataset.}}, author = {{Meyer, Maximilian Tim and Schindlmayr, Arno}}, issn = {{2673-8716}}, journal = {{Dynamics}}, number = {{3}}, publisher = {{MDPI}}, title = {{{Generalized Miller formulae for quantum anharmonic oscillators}}}, doi = {{10.3390/dynamics5030034}}, volume = {{5}}, year = {{2025}}, } @article{61821, abstract = {{AbstractControlling the surface orientation of DNA origami nanostructures (DON) is crucial for applications in nanotechnology and materials science. While previous work utilized various DON modifications, simple methods for controlling their landing orientation remain scarce. Here, we demonstrate a straightforward approach to control the adsorption orientation of chiral double‐L (CDL) DON on mica by tuning magnesium ion (Mg2⁺) concentration and exploiting global shape distortions. Using atomic force microscopy (AFM), we analyzed the resulting distribution of the mirror‐image orientations, referred to as S and Z orientations, at both buffer/mica and air/mica interfaces and identified conditions resulting in homogenous CDL orientation of 100% S. These results demonstrate how DON conformation and ionic environments influence DON orientation, offering insights for precise nanostructure deposition.}}, author = {{Velpula, Gangamallaiah and Tomm, Emilia and Shen, Boxuan and Mali, Kunal S. and Keller, Adrian Clemens and De Feyter, Steven}}, issn = {{1433-7851}}, journal = {{Angewandte Chemie International Edition}}, publisher = {{Wiley}}, title = {{{Breaking of the Up‐Down Symmetry of DNA Origami on a Solid Substrate}}}, doi = {{10.1002/anie.202507613}}, year = {{2025}}, }