@techreport{62981, abstract = {{Otus is a high-performance computing cluster that was launched in 2025 and is operated by the Paderborn Center for Parallel Computing (PC2) at Paderborn University in Germany. The system is part of the National High Performance Computing (NHR) initiative. Otus complements the previous supercomputer Noctua 2, offering approximately twice the computing power while retaining the three node types that were characteristic of Noctua 2: 1) CPU compute nodes with different memory capacities, 2) high-end GPU nodes, and 3) HPC-grade FPGA nodes. On the Top500 list, which ranks the 500 most powerful supercomputers in the world, Otus is in position 164 with the CPU partition and in position 255 with the GPU partition (June 2025). On the Green500 list, ranking the 500 most energy-efficient supercomputers in the world, Otus is in position 5 with the GPU partition (June 2025). This article provides a comprehensive overview of the system in terms of its hardware, software, system integration, and its overall integration into the data center building to ensure energy-efficient operation. The article aims to provide unique insights for scientists using the system and for other centers operating HPC clusters. The article will be continuously updated to reflect the latest system setup and measurements. }}, author = {{Ehtesabi, Sadaf and Hossain, Manoar and Kenter, Tobias and Krawinkel, Andreas and Ostermann, Lukas and Plessl, Christian and Riebler, Heinrich and Rohde, Stefan and Schade, Robert and Schwarz, Michael and Simon, Jens and Winnwa, Nils and Wiens, Alex and Wu, Xin}}, keywords = {{Otus, Supercomputer, FPGA, PC2, Paderborn Center for Parallel Computing, Noctua 2, HPC}}, pages = {{33}}, publisher = {{Paderborn Center for Parallel Computing (PC2)}}, title = {{{Otus Supercomputer}}}, doi = {{10.48550/ARXIV.2512.07401}}, volume = {{1}}, year = {{2025}}, } @article{56131, abstract = {{This article provides a comprehensive mathematical-didactic analysis of how the highly relevant topic symmetry can be prepared for the university education of PSTs. Methodologically, the analysis is embedded in a design research cycle and serves as preparation for the actual design of learning activities. The procedure of "specifying and structuring" learning objects is used and adapted in such a way that, in addition to mathematical aspects, profession-oriented references to school mathematics are also considered. An essential result of the analysis is the formulation of so-called interface aspects to symmetry, which prove to be helpful in establishing such references. }}, author = {{Hoffmann, Max}}, journal = {{Recherches en Didactique des Mathématiques}}, number = {{2}}, pages = {{85--120}}, title = {{{Symmetry as a Topic for the University Education of Pre-Service Teachers}}}, doi = {{10.46298/rdm.14256}}, volume = {{45}}, year = {{2025}}, } @inproceedings{65246, author = {{Hoffmann, Max}}, booktitle = {{Proceedings of the Fourteenth Congress of the European Society for Research in Mathematics Education (CERME14)}}, editor = {{Bosch, Marianna and Bolondi, Giorgio and Carreira, Susana and Gaidoschik, Michael and Spagnolo, Camilla}}, pages = {{2245--2252}}, publisher = {{Free University of Bozen-Bolzano and ERME}}, title = {{{Using scriptwriting as a response format for interface tasks: Exemplary analyses in the context of symmetry}}}, year = {{2025}}, } @inproceedings{63441, author = {{Moritzer, Elmar and Brandes, Philipp and Wittler, Maurice and Claes, Leander and Wippermann, Mareen and Henning, Bernd}}, booktitle = {{40th International Conference of the Polymer Processing Society}}, keywords = {{Faser-Kunststoff-Verbunde (FKV), Faserverstärkte Kunststoffe (FVK), Organobleche, Ultraschall}}, title = {{{Non-destructive fiber-matrix adhesion measurement of glass fiber reinforced thermoplastic composite laminates using ultrasound}}}, year = {{2025}}, } @inproceedings{59896, abstract = {{We present an electronic-photonic co-designed Mach-Zehnder modulator with linear segment drivers in a photonic SOI-CMOS technology with an EO 3-dB bandwidth of ≥ 27 GHz and data transmission up to 64 Gbit/s without pre-emphasis.}}, author = {{Kress, Christian and Schwabe, Tobias and Mihaylov, Martin Miroslavov and Scheytt, J. Christoph}}, location = {{Long Beach, CA, USA}}, title = {{{High-Speed Mach-Zehnder Modulator with Linear Segmented On-Chip Drivers in Photonic 45nm SOI-CMOS Technology }}}, year = {{2025}}, } @article{53413, abstract = {{For negatively curved symmetric spaces it is known that the poles of the scattering matrices defined via the standard intertwining operators for the spherical principal representations of the isometry group are either given as poles of the intertwining operators or as quantum resonances, i.e. poles of the meromorphically continued resolvents of the Laplace-Beltrami operator. We extend this result to classical locally symmetric spaces of negative curvature with convex-cocompact fundamental group using results of Bunke and Olbrich. The method of proof forces us to exclude the spectral parameters corresponding to singular Poisson transforms.}}, author = {{Delarue, Benjamin and Hilgert, Joachim}}, issn = {{0949-5932}}, journal = {{Journal of Lie Theory}}, number = {{(4)}}, pages = {{787----804}}, title = {{{Quantum resonances and scattering poles of classical rank one locally symmetric spaces}}}, volume = {{35}}, year = {{2025}}, } @inproceedings{60504, author = {{Nellius, Tom and Henne, Kevin and Hartinger, Maximilian and Meihost, Lars and Hetkämper, Tim and Zeipert, Henning and Claes, Leander and Henning, Bernd}}, location = {{Nürnberg}}, title = {{{Ultrasonic phased array interface using programmable I/O and microprocessor clock synchronisation}}}, doi = {{ 10.5162/SMSI2025/A5.4}}, year = {{2025}}, } @misc{64902, abstract = {{Diese Dissertation behandelt die Entwicklung, Erprobung und Evaluation einer mobilen Augmented Reality Anwendung (mAR-App) namens PEARL (Paderborner Elektrotechnik AR Laborpraktikum), die als Vorbereitungsmaßnahme für elektrotechnische Laborpraktika konzipiert wird. Ziel ist es, Studierenden eine zeitlich und örtlich flexible Möglichkeit zu bieten, den realitätsnahen Umgang mit Laborgeräten - primär dem Oszilloskop - zu erlernen. Die methodische Grundlage bilden der Makrozyklus von Design-Based Research (DBR) als strukturierender Rahmen und das heuristische Modell des Research Pentagons, das die Durchführung auf Mikroebene bestimmt. In insgesamt vier Research Pentagons werden didaktische, technologische, motivationale und evaluative Komponenten systematisch untersucht und weiterentwickelt. Das erste Pentagon fokussiert die Entwicklung eines didaktisch fundierten Konzepts nach dem Prinzip des Constructive Alignment, das Lernziele, Lernaktivitäten und Prüfungsformen in fünf abgestufte Lernlevel überführt. Diese reichen von der initialen Orientierung bis zur eigenständigen Problemlösung in einem freien Experimentiermodus. Im zweiten Research Pentagon wird die technische Machbarkeit von Augmented - und Virtual Reality (VR) im Laborumfeld anhand mehrerer funktionaler Prototypen evaluiert. Während sich VR aufgrund technischer Einschränkungen als ungeeignet erweist, zeigt AR - insbesondere in der markerlosen Ausführung mittels der Software Development Kits (SDKs) ARCore und ARKit - ein hohes Potenzial für den praktischen Einsatz. Im dritten Pentagon entsteht ein Onboarding-Modul, das auf die erste Version der mobilen App (V0.17.01) aufsetzt und grundlegende Funktionen eines realen Oszilloskops digital abbildet. Dabei werden Nutzer:innen schrittweise an das virtuelle Oszilloskop herangeführt und lernen zugleich die zentralen Funktionen der mAR-App kennen. Die Ergebnisse zeigen eine insgesamt neutrale bis leicht positive Nutzungserfahrung, wobei technische Schwächen (z.B. Reaktionszeit oder Objektverankerung) die Effizienz und Steuerbarkeit beeinträchtigen. Im Exkurs-Kapitel erfolgt eine Eye-Tracking-Studie zur Untersuchung visueller Aufmerksamkeit und individueller Lösungsstrategien von Expert:innen und Noviz:innen bei der Arbeit am realen Oszilloskop. Heatmaps und Zeitverläufe in definierten Areas of Interest (AOI) liefern erste Hinweise auf Unterschiede im Blickverhalten zwischen den Gruppen. Die algorithmischen Scanpfadanalysen der Blickverläufe hingegen zeigen eine geringe Trennschärfe. Das Potenzial von Eye-Tracking als Evaluationsmethode wird daher kritisch reflektiert, aber angesichts technologischer Entwicklungen und verfügbarer Eye-Tracker in Mixed Reality (MR) Brillen weiterhin als zukunftsrelevant eingeordnet. Die abschließende summative Evaluation nutzt ein Prä‑Post-Test-Design mit Kontrollgruppenvergleich mit 70 Teilnehmenden, um die Lernwirksamkeit der überarbeiteten mAR-App mit klassischen Materialien wie Videos und Handbüchern zu vergleichen. In der Interventionsgruppe (IG) zeigen sich auf kognitiver und affektiver Ebene signifikant positive Veränderungen: Die Leistungen steigen deutlich, insbesondere in den Taxonomiestufen Anwendung, Verständnis und Analyse; zugleich nehmen experimentelles Selbstkonzept und experimentelles Sachinteresse zu, während Überforderung und Ängstlichkeit im Hinblick auf die Laborpraktika abnehmen. Als Einschränkung zeigt sich, dass die mAR-App keinen klaren Vorsprung gegenüber der Kontrollgruppe (KG) erreicht, was sowohl auf die sehr gut ausgearbeiteten Materialien und Videos der KG als auch auf technische Begrenzungen der mobilen Umsetzung zurückzuführen ist: Kleine Displays, 2D-Oberflächen für 3D-Geräte und unpräzise Touch-Interaktionen erschweren komplexe, feinmotorische Aufgaben. In den begleitenden User Interface (UI) und User Experience (UX) Fragebögen spiegeln sich diese Limitationen in gemischten Bewertungen der App wider. Die Arbeit verdeutlicht, dass die mobile AR-Anwendung trotz technischer Einschränkungen wertvolle Möglichkeiten für die Vorbereitung auf Laborpraktika und das Kennenlernen von Laborgeräten bieten kann. Der Fokus bei der Entwicklung liegt von Beginn an auf einer modularen und flexiblen App-Architektur, um sie mit neuen Geräten und Aufgaben zu erweitern. Der Hauptnutzen liegt perspektivisch nicht in der mobilen Anwendung selbst, sondern in der strategischen Ausrichtung auf zukunftsfähige, skalierbare Lösungen für MR-Brillen. Diese erlauben eine authentische Gestensteuerung und realitätsnahe Interaktionen.}}, author = {{Alptekin, Mesut}}, publisher = {{LibreCat University}}, title = {{{Entwicklung einer Augmented Reality basierten Anwendung als Vorbereitungsmaßnahme zum Laborpraktikum in der Elektrotechnik}}}, doi = {{10.17619/UNIPB/1-2483}}, year = {{2025}}, } @inproceedings{65466, author = {{Bäumer, Fabian and Brinkmann, Marcus and Radoy, Maximilian and Schwenk, Jörg and Somorovsky, Juraj}}, booktitle = {{Proceedings of the 2025 ACM SIGSAC Conference on Computer and Communications Security}}, publisher = {{ACM}}, title = {{{On the Security of SSH Client Signatures}}}, doi = {{10.1145/3719027.3765079}}, year = {{2025}}, } @inproceedings{65474, author = {{Rook, Jeroen and López-Ibáñez, Manuel}}, booktitle = {{Proceedings of the Genetic and Evolutionary Computation Conference Companion, GECCO 2025, NH Malaga Hotel, Malaga, Spain, July 14-18, 2025}}, editor = {{Filipic, Bogdan}}, pages = {{1617–1642}}, publisher = {{ACM}}, title = {{{Advanced Use of Automatic Algorithm Configuration: Single- and Multi-Objective Approaches}}}, doi = {{10.1145/3712255.3716537}}, year = {{2025}}, } @inproceedings{59895, abstract = {{The generation of optically broadband Nyquist pulse sequences using an integrated Mach-Zehnder modulator (MZM) in a thin-film lithium-niobate (TFLN) platform with repetition rates of 5 to 32 GHz and optical bandwidths of up to 160 GHz is demonstrated. Nyquist pulse sequences with high optical bandwidth can be used as synchronization and control signals in quantum sources based on photon pair generation.}}, author = {{Kress, Christian and Mihaylov, Martin Miroslavov and Schwabe, Tobias and Silberhorn, Christine and Scheytt, J. Christoph}}, booktitle = {{PIERS Proceedings }}, location = {{Abu Dhabi}}, publisher = {{PhotonIcs and Electromagnetics Research Symposium (PIERS)}}, title = {{{Broadband Nyquist Pulse Generation on TFLN Platform for Integrated Quantum Source}}}, doi = {{10.1109/PIERS-Spring66516.2025.11276835}}, year = {{2025}}, } @unpublished{61778, abstract = {{Understanding the entanglement structure of local Hamiltonian ground spaces is a physically motivated problem, with applications ranging from tensor network design to quantum error-correcting codes. To this end, we study the complexity of estimating ground state entanglement, and more generally entropy estimation for low energy states and Gibbs states. We find, in particular, that the classes qq-QAM [Kobayashi, le Gall, Nishimura, SICOMP 2019] (a quantum analogue of public-coin AM) and QMA(2) (QMA with unentangled proofs) play a crucial role for such problems, showing: (1) Detecting a high-entanglement ground state is qq-QAM-complete, (2) computing an additive error approximation to the Helmholtz free energy (equivalently, a multiplicative error approximation to the partition function) is in qq-QAM, (3) detecting a low-entanglement ground state is QMA(2)-hard, and (4) detecting low energy states which are close to product states can range from QMA-complete to QMA(2)-complete. Our results make progress on an open question of [Bravyi, Chowdhury, Gosset and Wocjan, Nature Physics 2022] on free energy, and yield the first QMA(2)-complete Hamiltonian problem using local Hamiltonians (cf. the sparse QMA(2)-complete Hamiltonian problem of [Chailloux, Sattath, CCC 2012]).}}, author = {{Gharibian, Sevag and Kamminga, Jonas}}, booktitle = {{arXiv:2510.06796}}, title = {{{On the complexity of estimating ground state entanglement and free energy}}}, year = {{2025}}, } @inproceedings{62108, author = {{Luchterhandt, Lars and Govindasamy, Vivek and Wang, Yutong and Scheytt, Christoph and Mueller, Wolfgang and Dömer, Rainer}}, booktitle = {{2025 Forum on Specification & Design Languages (FDL)}}, publisher = {{IEEE}}, title = {{{A Quantitative Guide to Navigate Speed/Accuracy Tradeoffs in System Level Design of RISC-V Processor Grids}}}, doi = {{10.1109/fdl68117.2025.11165408}}, year = {{2025}}, } @inproceedings{65618, author = {{Bröker, Mika and Menzel, Johannes and Plessl, Christian}}, booktitle = {{Proceedings of the 15th International Symposium on Highly Efficient Accelerators and Reconfigurable Technologies}}, publisher = {{ACM}}, title = {{{Evaluating the Strong Scaling Potential of AI Engines for Molecular Dynamics Simulations}}}, doi = {{10.1145/3728179.3728187}}, year = {{2025}}, } @inproceedings{50272, abstract = {{Despite the fundamental role the Quantum Satisfiability (QSAT) problem has played in quantum complexity theory, a central question remains open: At which local dimension does the complexity of QSAT transition from "easy" to "hard"? Here, we study QSAT with each constraint acting on a $k$-dimensional and $l$-dimensional qudit pair, denoted $(k,l)$-QSAT. Our first main result shows that, surprisingly, QSAT on qubits can remain $\mathsf{QMA}_1$-hard, in that $(2,5)$-QSAT is $\mathsf{QMA}_1$-complete. In contrast, $2$-SAT on qubits is well-known to be poly-time solvable [Bravyi, 2006]. Our second main result proves that $(3,d)$-QSAT on the 1D line with $d\in O(1)$ is also $\mathsf{QMA}_1$-hard. Finally, we initiate the study of 1D $(2,d)$-QSAT by giving a frustration-free 1D Hamiltonian with a unique, entangled ground state. Our first result uses a direct embedding, combining a novel clock construction with the 2D circuit-to-Hamiltonian construction of [Gosset, Nagaj, 2013]. Of note is a new simplified and analytic proof for the latter (as opposed to a partially numeric proof in [GN13]). This exploits Unitary Labelled Graphs [Bausch, Cubitt, Ozols, 2017] together with a new "Nullspace Connection Lemma", allowing us to break low energy analyses into small patches of projectors, and to improve the soundness analysis of [GN13] from $\Omega(1/T^6)$ to $\Omega(1/T^2)$, for $T$ the number of gates. Our second result goes via black-box reduction: Given an arbitrary 1D Hamiltonian $H$ on $d'$-dimensional qudits, we show how to embed it into an effective null-space of a 1D $(3,d)$-QSAT instance, for $d\in O(1)$. Our approach may be viewed as a weaker notion of "simulation" (\`a la [Bravyi, Hastings 2017], [Cubitt, Montanaro, Piddock 2018]). As far as we are aware, this gives the first "black-box simulation"-based $\mathsf{QMA}_1$-hardness result, i.e. for frustration-free Hamiltonians.}}, author = {{Rudolph, Dorian and Gharibian, Sevag and Nagaj, Daniel}}, booktitle = {{16th Innovations in Theoretical Computer Science (ITCS)}}, number = {{85}}, pages = {{1--24}}, title = {{{Quantum 2-SAT on low dimensional systems is $\mathsf{QMA}_1$-complete: Direct embeddings and black-box simulation}}}, doi = {{10.4230/LIPIcs.ITCS.2025.85}}, volume = {{325}}, year = {{2025}}, } @article{55037, abstract = {{Estimating ground state energies of many-body Hamiltonians is a central task in many areas of quantum physics. In this work, we give quantum algorithms which, given any $k$-body Hamiltonian $H$, compute an estimate for the ground state energy and prepare a quantum state achieving said energy, respectively. Specifically, for any $\varepsilon>0$, our algorithms return, with high probability, an estimate of the ground state energy of $H$ within additive error $\varepsilon M$, or a quantum state with the corresponding energy. Here, $M$ is the total strength of all interaction terms, which in general is extensive in the system size. Our approach makes no assumptions about the geometry or spatial locality of interaction terms of the input Hamiltonian and thus handles even long-range or all-to-all interactions, such as in quantum chemistry, where lattice-based techniques break down. In this fully general setting, the runtime of our algorithms scales as $2^{cn/2}$ for $c<1$, yielding the first quantum algorithms for low-energy estimation breaking the natural bound based on Grover search. The core of our approach is remarkably simple, and relies on showing that any $k$-body Hamiltonian has a low-energy subspace of exponential dimension.}}, author = {{Buhrman, Harry and Gharibian, Sevag and Landau, Zeph and Gall, François Le and Schuch, Norbert and Tamaki, Suguru}}, journal = {{Physical Review Letters}}, pages = {{030601}}, title = {{{Beating Grover search for low-energy estimation and state preparation}}}, doi = {{10.1103/29qw-bssx}}, volume = {{135}}, year = {{2025}}, } @unpublished{61776, abstract = {{We investigate the role of energy, i.e. average photon number, as a resource in the computational complexity of bosonic systems. We show three sets of results: (1. Energy growth rates) There exist bosonic gate sets which increase energy incredibly rapidly, obtaining e.g. infinite energy in finite/constant time. We prove these high energies can make computing properties of bosonic computations, such as deciding whether a given computation will attain infinite energy, extremely difficult, formally undecidable. (2. Lower bounds on computational power) More energy ``='' more computational power. For example, certain gate sets allow poly-time bosonic computations to simulate PTOWER, the set of deterministic computations whose runtime scales as a tower of exponentials with polynomial height. Even just exponential energy and $O(1)$ modes suffice to simulate NP, which, importantly, is a setup similar to that of the recent bosonic factoring algorithm of [Brenner, Caha, Coiteux-Roy and Koenig (2024)]. For simpler gate sets, we show an energy hierarchy theorem. (3. Upper bounds on computational power) Bosonic computations with polynomial energy can be simulated in BQP, ``physical'' bosonic computations with arbitrary finite energy are decidable, and the gate set consisting of Gaussian gates and the cubic phase gate can be simulated in PP, with exponential bound on energy, improving upon the previous PSPACE upper bound. Finally, combining upper and lower bounds yields no-go theorems for a continuous-variable Solovay--Kitaev theorem for gate sets such as the Gaussian and cubic phase gates.}}, author = {{Chabaud, Ulysse and Gharibian, Sevag and Mehraban, Saeed and Motamedi, Arsalan and Naeij, Hamid Reza and Rudolph, Dorian and Sambrani, Dhruva}}, booktitle = {{arXiv:2510.08545}}, title = {{{Energy, Bosons and Computational Complexity}}}, year = {{2025}}, } @unpublished{60432, abstract = {{The Quantum k-SAT problem is the quantum generalization of the k-SAT problem. It is the problem whether a given local Hamiltonian is frustration-free. Frustration-free means that the ground state of the k-local Hamiltonian minimizes the energy of every local interaction term simultaneously. This is a central question in quantum physics and a canonical QMA_1-complete problem. The Quantum k-SAT problem is not as well studied as the classical k-SAT problem in terms of special tractable cases, approximation algorithms and parameterized complexity. In this paper, we will give a graph-theoretic study of the Quantum k-SAT problem with the structures core and radius. These hypergraph structures are important to solve the Quantum k-SAT problem. We can solve a Quantum k-SAT instance in polynomial time if the derived hypergraph has a core of size n-m+a, where a is a constant, and the radius is at most logarithmic. If it exists, we can find a core of size n-m+a with the best possible radius in polynomial time, whereas finding a general minimum core with minimal radius is NP-hard.}}, author = {{Kremer, Simon-Luca and Rudolph, Dorian and Gharibian, Sevag}}, booktitle = {{arXiv:2506.17066}}, title = {{{Quantum k-SAT Related Hypergraph Problems}}}, year = {{2025}}, } @article{63440, author = {{Moritzer, Elmar and Brandes, Philipp and Westphal, Max Siegfried and Claes, Leander and Wippermann, Mareen and Düchting, Julia and Henning, Bernd}}, journal = {{WAK Jahresmagazin}}, keywords = {{Faser-Kunststoff-Verbunde (FKV), Faserverstärkte Kunststoffe (FVK), Organobleche, Ultraschall}}, pages = {{26–29}}, title = {{{Zerstörungsfreie Ultraschall-Prüfung von Organoblechen}}}, volume = {{2025}}, year = {{2025}}, } @inproceedings{61256, author = {{Illian, Marvin and Luchterhandt, Björn and Wang, Lin}}, booktitle = {{Proceedings of the 20th Workshop on Mobility in the Evolving Internet Architecture (MobiArch)}}, location = {{Hong Kong, China}}, title = {{{Band Switching for Mobile Energy Optimization in 5G Networks and Beyond}}}, doi = {{10.1145/3737897.3767294}}, year = {{2025}}, }