@article{45291, author = {{Cramer, Katja and Webersen, Yvonne}}, journal = {{MNU-Journal}}, pages = {{237--243}}, title = {{{"Heute wissen wir, wie das Universum aussieht!" ...oder? Eine digitale Lernumgebung zur Vorläufigkeit von naturwissenschaftlichem Wissen am Beispiel der Geschichte der Astronomie}}}, volume = {{3}}, year = {{2025}}, } @inproceedings{60022, author = {{Brauckmann, Michael and Narvaez Castaneda, Emmanuel and Siebert, Dustin and Brecht, Benjamin and Förstner, Jens and Zentgraf, Thomas}}, booktitle = {{Proceedings of The 15th International Conference on Metamaterials, Photonic Crystals and Plasmonics}}, location = {{Malaga, Spain}}, title = {{{Enhancement Of Light-matter Interaction In Topological Waveguides And Resonators}}}, year = {{2025}}, } @article{63734, abstract = {{Quantum dots (QDs) are a promising source of single photons mainly due to their on-demand operation. However, their emission wavelength depends on their size and immediate surroundings in the solid-state environment. By applying a serrodyne electro-optic phase modulation, we achieve a spectral shift up to 0.01 nm (3.5 GHz) while preserving the purity and indistinguishability of the photons. This method provides an efficient and scalable approach for tuning the emission wavelength of QDs without relying on nonlinear frequency mixing or probabilistic processes. Our results show that the electro-optic phase modulation enables stable and tunable spectral shifts, making it suitable for applications such as quantum communication, quantum key distribution, and primarily integrating remote quantum dot sources into large-scale quantum networks.}}, author = {{Kapoor, Sanjay and Rodek, Aleksander and Mikołajczyk, Michał and Szuniewicz, Jerzy and Sośnicki, Filip Maksymilian and Kazimierczuk, Tomasz and Kossacki, Piotr and Karpiński, Michał}}, issn = {{2192-8614}}, journal = {{Nanophotonics}}, number = {{11}}, pages = {{1775--1782}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Electro-optic frequency shift of single photons from a quantum dot}}}, doi = {{10.1515/nanoph-2024-0550}}, volume = {{14}}, year = {{2025}}, } @article{63732, abstract = {{Time lenses have been recognized as crucial components for manipulating ultrafast optical pulses in various applications, from ultrafast spectroscopy to the interfacing of optical quantum systems. A time lens is characterized by its chirp rate, which determines the focusing strength of the time lens, and accurate knowledge of this chirp is critical for precise dispersion compensation and minimizing aberrations. Here, we introduce a tunable time aperture model for sinusoidal time lenses that provides a more accurate estimate of the effective chirp rate without modifying the device. We derive a closed-form expression for the maximum phase error and show how it depends on the time aperture. We experimentally demonstrate a 1.6-fold improvement in spectral bandwidth compression of Gaussian pulses compared to the conventional approach. Our framework offers a practical tool for designing efficient temporal optical systems, benefiting applications in both classical and quantum optics where accurate spectro-temporal shaping is essential.}}, author = {{Kapoor, Sanjay and Sośnicki, Filip Maksymilian and Karpiński, Michał}}, issn = {{2378-0967}}, journal = {{APL Photonics}}, number = {{9}}, publisher = {{AIP Publishing}}, title = {{{Aberration-optimized electro-optic time lens model using a tunable aperture}}}, doi = {{10.1063/5.0270904}}, volume = {{10}}, year = {{2025}}, } @article{63744, abstract = {{Orbital angular momentum (OAM) modes are an important resource used in various branches of quantum science and technology due to their unique helical structure and countably infinite basis. Generating light that simultaneously carries high-order orbital angular momenta and exhibits quantum correlations is a challenging task. In this work, we present a theoretical approach to the generation of correlated Schmidt modes carrying OAM via parametric down-conversion (PDC) in cascaded nonlinear systems (nonlinear interferometers) pumped by Laguerre–Gaussian beams. We demonstrate how the number of generated modes and their population can be controlled by varying the pump parameters, the gain of the PDC process, and the distance between the crystals. We investigate the angular displacement measurement uncertainty of these interferometers and demonstrate that it can overcome the classical shot noise limit.}}, author = {{Scharwald, Dennis and Gehse, Lucas and Sharapova, Polina}}, issn = {{2378-0967}}, journal = {{APL Photonics}}, number = {{1}}, publisher = {{AIP Publishing}}, title = {{{Schmidt modes carrying orbital angular momentum generated by cascaded systems pumped with Laguerre–Gaussian beams}}}, doi = {{10.1063/5.0229802}}, volume = {{10}}, year = {{2025}}, } @misc{63855, abstract = {{Elektronenenergieverlustspektroskopie (engl. EELS) ist eine fortgeschrittene Analysemethode der Transmissionselektronenmikroskopie, die auf atomarer Ebene Einblicke in Materialcharakteristika wie bspw. Eigenschaften des Elektronensystems oder der Materialzusammensetzung erlaubt. Die Genauigkeit jeder EELS-Analyse ist jedoch fundamental durch Rauschen und Unschärfe begrenzt. Diese Thesis beschreibt solche Rauschphänomene im Detail. Vor allem bei strahlempfindlichen Materialien, die kurze Bestrahlzeiten erfordern, aber auch bei Elektron-Materie-Wechselwirkungen mit geringer Auftrittshäufigkeit, ist eine solche Beschreibung notwendig, da das Rauschen solche Messungen dominiert. Zusätzlich spielen Korrelationen des Rauschens eine Rolle, die durch Faltung des verrauschten Signals mit der Punktspreizfunktion des Detektors entstehen und die sowohl theoretisch als auch experimentell beschrieben werden. Methoden zur Messung der wichtigsten Rauschparameter bei typischen Detektorsystemen werden vorgestellt und erlauben es, das Rauschmodel auf jeden beliebigen EELS-Detektor anzupassen. Eine neue Entfaltungsmethode wird vorgeschlagen, die EELS-Messungen schärft und entrauscht. Die Wirksamkeit dieser Methode wird an Simulations- und Experimentaldaten dargelegt. Hierbei wird gezeigt, dass die neue Methode signifikant bessere Ergebnisse liefert, als bisherige und somit eine Analyse von Messdaten auf einem Level ermöglicht, das die Möglichkeiten der Elektronenmikroskopie deutlich erweitert.}}, 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{59178, author = {{Zietlow, Christian and Lindner, Jörg}}, issn = {{2045-2322}}, journal = {{Sci Rep}}, number = {{1}}, pages = {{3815}}, title = {{{An applied noise model for scintillation-based CCD detectors in transmission electron microscopy.}}}, doi = {{10.1038/s41598-025-85982-4}}, volume = {{15}}, year = {{2025}}, } @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{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}}, } @unpublished{57235, author = {{Weiler, David and Burde, Jan-Philipp and Costan, Kasim and Große-Heilmann, Rike Isabel and Kulgemeyer, Christoph and Lässer, Armin and Riese, Josef and Schubatzky, Thomas}}, booktitle = {{Lernen, lehren und forschen im Schülerlabor. Gesellschaft Für Didaktik Der Chemie Und Physik Jahrestagung 2024 in Bochum}}, title = {{{Bedürfnisse von Lehrkräften zu digitalen Medien adressieren! }}}, year = {{2025}}, } @unpublished{58544, abstract = {{We introduce a new classification of multimode states with a fixed number of photons. This classification is based on the factorizability of homogeneous multivariate polynomials and is invariant under unitary transformations. The classes physically correspond to field excitations in terms of single and multiple photons, each of which being in an arbitrary irreducible superposition of quantized modes. We further show how the transitions between classes are rendered possible by photon addition, photon subtraction, and photon-projection nonlinearities. We explicitly put forward a design for a multilayer interferometer in which the states for different classes can be generated with state-of-the-art experimental techniques. Limitations of the proposed designs are analyzed using the introduced classification, providing a benchmark for the robustness of certain states and classes. }}, author = {{Kopylov, Denis and Offen, Christian and Ares, Laura and Wembe Moafo, Boris Edgar and Ober-Blöbaum, Sina and Meier, Torsten and Sharapova, Polina and Sperling, Jan}}, title = {{{Multiphoton, multimode state classification for nonlinear optical circuits }}}, 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}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Nonreciprocal Metasurfaces with Epsilon-Near-Zero Materials}}}, doi = {{10.1021/acs.nanolett.4c06188}}, year = {{2025}}, } @article{58885, abstract = {{There have been several attempts to conceptualize and operationalize pedagogical content knowledge (PCK) in the context of teachers' professional competencies. A recent and popular model is the Refined Consensus Model (RCM), which proposes a framework of dispositional competencies (personal PCK—pPCK) that influence more action-related competencies (enacted PCK—ePCK) and vice versa. However, descriptions of the internal structure of pPCK and possible knowledge domains that might develop independently are still limited, being either primarily theoretically motivated or strictly hierarchical and therefore of limited use, for example, for formative feedback and further development of the RCM. Meanwhile, a non-hierarchical differentiation for the ePCK regarding the plan-teach-reflect cycle has emerged. In this study, we present an exploratory computational approach to investigate pre-service teachers' pPCK for a similar non-hierarchical structure using a large dataset of responses to a pPCK questionnaire (N=846). We drew on theoretical foundations and previous empirical findings to achieve interpretability by integrating this external knowledge into our analyses using the Computational Grounded Theory (CGT) framework. The results of a cluster analysis of the pPCK scores indicate the emergence of prototypical groups, which we refer to as competency profiles: (1) a group with low performance, (2) a group with relatively advanced competency in using pPCK to create instructional elements, (3) a group with relatively advanced competency in using pPCK to assess and analyze described instructional elements, and (4) a group with high performance. These groups show tendencies for certain language usage, which we analyze using a structural topic model in a CGT-inspired pattern refinement step. We verify these patterns by demonstrating the ability of a machine learning model to predict the competency profile assignments. Finally, we discuss some implications of the results for the further development of the RCM and their potential usability for an automated formative assessment.}}, author = {{Zeller, Jannis and Riese, Josef}}, issn = {{1098-2736}}, journal = {{Journal of Research in Science Teaching}}, keywords = {{computational grounded theory, language analysis, machine learning, pedagogical content knowledge, unsupervised learning}}, title = {{{Competency Profiles of PCK Using Unsupervised Learning: What Implications for the Structures of pPCK Emerge From Non-Hierarchical Analyses?}}}, doi = {{10.1002/tea.70001}}, year = {{2025}}, } @article{58907, author = {{Hörnlein, Madeleine}}, journal = {{die hochschullehre}}, title = {{{Physik lernen durch Erklären? - Evaluation eines Seminarkonzepts für Sachunterrichtsstudierende}}}, doi = {{https://dx.doi.org/10.3278/HSL2462W}}, volume = {{11}}, year = {{2025}}, } @article{58658, author = {{Webersen, Yvonne and Riese, Josef}}, journal = {{HLZ – Herausforderung Lehrer*innenbildung}}, number = {{1}}, title = {{{Umdenken! Vom fachlichen zum schulischen Experimentieren. Vorstellung einer Lehrkonzeption für angehende Physiklehrkräfte. }}}, doi = {{10.11576/hlz-7118}}, volume = {{8}}, year = {{2025}}, } @article{58977, author = {{Schubatzky, Thomas and Burde, Jan-Philipp and Große-Heilmann, Rike Isabel and Lachner, Andreas and Riese, Josef and Weiler, David}}, issn = {{2666-5573}}, journal = {{Computers and Education Open}}, publisher = {{Elsevier BV}}, title = {{{From Knowledge To Intention: The Role Of TPACK And Self-Efficacy In Technology Integration}}}, doi = {{10.1016/j.caeo.2025.100246}}, year = {{2025}}, } @article{59069, abstract = {{Stable and bright single photon sources are key components for future quantum applications. A simple fabrication method is an important requirement for such sources. Here, we present a single photon source based on diced ridge waveguides in titanium indiffused LiNbO3. These waveguides can be easily fabricated by combining planar titanium in-diffusion without lithographic patterning and easy-to-handle precision dicing. Such devices have the potential to generate high single photon rates because ridge structures are typically less prone to the photorefractive effect. We achieve waveguide propagation losses <0.4dBcm and a SHG conversion efficiency of about 81%Wcm2. Harnessing a type-0 SPDC process to generate 1550 nm photons, we obtain a SPDC brightness of 3⋅1051s⋅mW⋅nm, with a heralding efficiency of ηh=45% (ηh,wg=77.5% for the waveguide itself excluded setup losses) and a heralded second-order correlation function of gh2(0)<0.003 at low pump powers.}}, author = {{Kießler, Christian and Kirsch, Michelle and Lengeling, Sebastian and Herrmann, Harald and Silberhorn, Christine}}, issn = {{2770-0208}}, journal = {{Optics Continuum}}, number = {{3}}, publisher = {{Optica Publishing Group}}, title = {{{SPDC single-photon source in Ti-indiffused diced ridge LiNbO3 waveguides}}}, doi = {{10.1364/optcon.557439}}, volume = {{4}}, year = {{2025}}, } @article{59176, abstract = {{Das fachdidaktische Wissen (FDW) stellt eine wichtige Komponente des Professionswissens von (angehenden) Lehrkräften dar. Es liegen bereits empirische Forschungsergebnisse zu Einflussfaktoren und zur Entwicklung des FDW sowie zur Bedeutung des FDW als Ganzem für Professionswissen und Qualität professioneller Handlungen vor. Für eine detailliertere Forschung zur Zusammenhangsstruktur zwischen FDW und der Performanz in prototypischen Handlungssituationen sind darüber hinaus differenziertere empirisch begründete Beschreibungen der inneren Struktur des FDW notwendig. Bisher sind entsprechende Ansätze allerdings zumeist primär theoretisch-normativ begründet oder auf hierarchische Betrachtungen beschränkt. Im vorliegenden Beitrag wird daher ein Ansatz zur nicht-hierarchischen datenbasierten Beschreibung latenter Kompetenzprofile des FDW orientiert an der Computational Grounded Theory vorgestellt. Dabei wird zunächst mithilfe eines Datensatzes von 846 Bearbeitungen des Physik-FDW-Testinstruments in überwiegend offenem Antwortformat aus dem Projekt ProfiLe-P+ eine latente Profilanalyse zur Untersuchung latenter FDW-Profile unter Fokus auf kognitive Anforderungen als empirisch trennbare Subskalen des FDW durchgeführt. Mithilfe von Topic Modeling werden anschließend Tendenzen in der Sprachnutzung der FDW-Profile untersucht. Um die Ergebnisse im Sinne der Computational Grounded Theory durch den Nachweis latenter Zusammenhänge zwischen den Testantworten der Proband:innen und der FDW-Profil-Zuordnung zu bestätigen, wird im Anschluss ein Machine-Learning-basiertes System zur automatisierten Zuordnung von Testbearbeitungen zu den FDW-Profilen erstellt. Es zeigen sich vier latente Kompetenzprofile mit nicht-hierarchischem Charakter. In einer längsschnittlichen Betrachtung wird abschließend die Entwicklung von Proband:innen im Kontext dieser FDW-Profile dargestellt. Die Ergebnisse bieten Ansatzmöglichkeiten zukünftig Untersuchungen der Zusammenhänge einzelner FDW-Komponenten und beispielsweise gezeigter Handlungsqualität auf Detailebene zu untersuchen.}}, author = {{Zeller, Jannis and Riese, Josef}}, issn = {{0949-1147}}, journal = {{Zeitschrift für Didaktik der Naturwissenschaften}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Machine-Learning basierte Analyse von latenten Profilen des physikdidaktischen Wissens Machine-Learning-Based Analysis of Latent Profiles in Physics PCK}}}, doi = {{10.1007/s40573-025-00181-y}}, volume = {{31}}, year = {{2025}}, }