@article{19639, abstract = {Magnetic interactions are thought to play a key role in the properties of many unconventional superconductors, including cuprates, iron pnictides, and square-planar nickelates. Superconductivity was also recently observed in the bilayer and trilayer Ruddlesden-Popper nickelates, the electronic structure of which is expected to differ from that of cuprates and square-planar nickelates. Here we study how electronic structure and magnetic interactions evolve with the number of layers, 𝑛, in thin film Ruddlesden-Popper nickelates Nd𝑛+1⁹Ni𝑛ⁱO3ⁱ𝑛+1 with 𝑛=1,3, and 5 using resonant inelastic x-ray scattering (RIXS). The RIXS spectra are consistent with a high-spin |3ⁱ𝑑8⁹ 𝐿ÌČ⟩ electronic configuration, resembling that of La2âˆ’đ‘„âąSrđ‘„âąNiO4 and the parent perovskite, NdNiO3. The magnetic excitations soften to lower energy in the structurally self-doped, higher-𝑛 films. Our observations confirm that structural tuning is an effective route for altering electronic properties, such as magnetic superexchange, in this prominent family of materials.}, author = {Tenhuisen, Sophia F.R. and Pan, Grace A. and Song, Qi and Baykusheva, Denitsa Rangelova and Ferenc Segedin, Dan and Goodge, Berit H. and Paik, Hanjong and Pelliciari, Jonathan and Bisogni, Valentina and Gu, Yanhong and Agrestini, Stefano and Nag, Abhishek and GarcĂ­a-FernĂĄndez, Mirian and Zhou, Ke Jin and Kourkoutis, Lena F. and Brooks, Charles M. and Mundy, Julia A. and Dean, Mark P.M. and Mitrano, Matteo}, issn = {2469-9969}, journal = {Physical Review B}, number = {16}, publisher = {American Physical Society}, title = {{Magnetic excitations in Ndn+1Nin O3n+1 Ruddlesden-Popper nickelates observed via resonant inelastic x-ray scattering}}, doi = {10.1103/PhysRevB.111.165145}, volume = {111}, year = {2025}, } @inproceedings{20054, author = {Horta, Sharona}, booktitle = {Proceedings of the MATSUS Spring 2025 Conference}, location = {Sevilla, Spain}, publisher = {FundaciĂł de la comunitat valenciana SCITO}, title = {{Solid state diffusion in metal-semiconductors core-shell nanoparticle}}, doi = {10.29363/nanoge.matsusspring.2025.220}, year = {2025}, } @article{20043, abstract = {We establish an isomorphism of complex K-theory of the moduli space M of “SL n​ ”-Higgs bundles of degree d and rank n (in the sense of Hausel–Thaddeus) and twisted complex K-theory of the orbifold M of PGL n​ -Higgs bundles of degree e, where (n,d)=(n,e)=1. Along the way, we prove the vanishing of torsion for H ∗ ( M ) and certain twisted complex K-theory groups of M . We also extend Arinkin’s autoduality of compactified Jacobian to a derived equivalence between SL n​ - and PGL n​ -Hitchin systems over the elliptic locus. In the appendix, we develop a formalism of G-sheaves of spectra, generalising equivariant homotopy theory to a relative setting.}, author = {Groechenig, Michael and Shen, Shiyu}, issn = {1435-9863}, journal = {Journal of the European Mathematical Society}, publisher = {EMS Press}, title = {{Complex K-theory of moduli spaces of Higgs bundles}}, doi = {10.4171/jems/1601}, year = {2025}, } @inproceedings{20051, abstract = {We revisit the majority problem in the population protocol communication model, as first studied by Angluin et al. (Distributed Computing 2008). We consider a more general version of this problem known as plurality consensus, which has already been studied intensively in the literature. In this problem, each node in a system of n nodes, has initially one of k different opinions, and they need to agree on the (relative) majority opinion. In particular, we consider the important and intensively studied model of Undecided State Dynamics. Our main contribution is an almost tight lower bound on the stabilization time: we prove that there exists an initial configuration, even with bias \Delta = \omega(\sqrt{n\log n}), where stabilization requires \Omega(kn\log \frac {\sqrt n} {k \log n}) interactions, or equivalently, \Omega(k\log \frac {\sqrt n} {k \log n}) parallel time for any k = o\left(\frac {\sqrt n}{\log n}\right). This bound is tight for any k \le n^{\frac 1 2 - \epsilon}, where \epsilon >0 can be any small constant, as Amir et al.~(PODC'23) gave a O(k\log n) parallel time upper bound for k = O\left(\frac {\sqrt n} {\log ^2 n}\right).}, author = {El-Hayek, Antoine and ElsĂ€sser, Robert and Schmid, Stefan}, booktitle = {Proceedings of the ACM Symposium on Principles of Distributed Computing}, isbn = { 9798400718854}, location = {Huatulco, Mexico}, publisher = {Association for Computing Machinery}, title = {{An almost tight lower bound for plurality consensus with undecided state dynamics in the population protocol model}}, doi = {10.1145/3732772.3733505}, year = {2025}, } @inproceedings{19982, abstract = {Dynamically maintaining the minimum cut in a graph G under edge insertions and deletion is a fundamental problem in dynamic graph algorithms for which no conditional lower bound on the time per operation exists. In an n-node graph the best known (1 + o (1))-approximate algorithm takes update time [14]. If the minimum cut is guaranteed to be (log n )o (1), a deterministic exact algorithm with n o (1) update time exists [8]. We present the first fully dynamic algorithm for (1 + o (1))-approximate minimum cut with n o(1) update time. Our main technical contribution is to show that it suffices to consider small-volume cuts in suitably contracted graphs.}, author = {El-Hayek, Antoine and Henzinger, Monika H and Li, Jason}, booktitle = {Proceedings of the 2025 Annual ACM-SIAM Symposium on Discrete Algorithms}, location = {New Orleans, LA, United States}, pages = {750--784}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Fully dynamic approximate minimum cut in subpolynomial time per operation}}, doi = {10.1137/1.9781611978322.22}, year = {2025}, } @article{20669, abstract = {Ice cliffs and supraglacial ponds are key drivers of mass loss on debris-covered glaciers. However, the relationship between melt ponds and adjacent ice cliffs has not been fully explored. We investigated the seasonal drainage patterns of a melt pond on the debris-covered Zhuxi Glacier in southeast Tibet and estimated the mass loss of its adjacent ice cliff during 2023-2024. Using hourly time-lapse photogrammetry we built a series of high-resolution point clouds to quantify the evolution of the ice cliff-pond system. Our findings indicate that subaerial melting and undercutting were the primary mechanisms of ice cliff mass loss during summer. In winter when the pond water level dropped, ice cliff calving became the dominant mode of ice loss. As the water level rose in spring, calving and subaerial melting occurred simultaneously and ice loss from calving accounted for approximately 19.5 % of total ice loss from February to July 2024. Our results reveal the transitional state of this ice cliff-pond system, exhibiting characteristics of both melt hotspots and lake-terminating calving fronts, and highlight the interplay between seasonal drainage-refill pond and differing modes of ice loss on adjacent ice cliff. Future research should focus on additional high-resolution monitoring of similar systems and incorporation of ice cliff-pond dynamics in glacier-scale numerical models. }, author = {He, Zhen and Westoby, Matthew and Ren, Shaoting and Zhao, Chuanxi and He, Yifei and Zhang, Tianzhao and Yang, Wei}, issn = {1727-5652}, journal = {Journal of Glaciology}, publisher = {Cambridge University Press}, title = {{Quantifying the seasonal dynamics of a transitional ice cliff-pond system on a debris-covered glacier}}, doi = {10.1017/jog.2025.10104}, volume = {71}, year = {2025}, } @inproceedings{19741, abstract = {Quantitative automata model beyond-boolean aspects of systems: every execution is mapped to a real number by incorporating weighted transitions and value functions that generalize acceptance conditions of boolean w-automata. Despite the theoretical advances in systems analysis through quantitative automata, the first comprehensive software tool for quantitative automata (Quantitative Automata Kit, or QuAK) was developed only recently. QuAK implements algorithms for solving standard decision problems, e.g., emptiness and universality, as well as constructions for safety and liveness of quantitative automata. We present the architecture of QuAK, which reflects that all of these problems reduce to either checking inclusion between two quantitative automata or computing the highest value achievable by an automaton—its so-called top value. We improve QuAK by extending these two algorithms with an option to return, alongside their results, an ultimately periodic word witnessing the algorithm’s output, as well as implementing a new safety-liveness decomposition algorithm that can handle nondeterministic automata, making QuAK more informative and capable.}, author = {Chalupa, Marek and Henzinger, Thomas A and Mazzocchi, Nicolas Adrien and Sarac, Naci E}, booktitle = {31st International Conference on Tools and Algorithms for the Construction and Analysis of Systems}, isbn = {9783031906428}, issn = {1611-3349}, pages = {303--312}, publisher = {Springer Nature}, title = {{Automating the analysis of quantitative automata with QuAK}}, doi = {10.1007/978-3-031-90643-5_16}, volume = {15696}, year = {2025}, } @unpublished{21858, abstract = {The recent surge in high-quality open-source Generative AI text models (colloquially: LLMs), as well as efficient finetuning techniques, have opened the possibility of creating high-quality personalized models that generate text attuned to a specific individual’s needs and are capable of credibly imitating their writing style by refining an open-source model with that person’s own data. The technology to create such models is accessible to private individuals, and training and running such models can be done cheaply on consumer-grade hardware. While these advancements are a huge gain for usability and privacy, this position paper argues that the practical feasibility of impersonating specific individuals also introduces novel safety risks. For instance, this technology enables the creation of phishing emails or fraudulent social media accounts, based on small amounts of publicly available text, or by the individuals themselves to escape AI text detection. We further argue that these risks are complementary to—and distinct from—the much-discussed risks of other impersonation attacks such as image, voice, or video deepfakes, and are not adequately addressed by the larger research community, or the current generation of open- and closed-source models.}, author = {Iofinova, Eugenia B and Jovanovic, Andrej and Alistarh, Dan-Adrian}, booktitle = {arXiv}, title = {{Position: It's time to act on the risk of efficient personalized text generation}}, doi = {10.48550/arXiv.2502.06560}, year = {2025}, } @article{21144, abstract = {This paper deals with the algorithmic aspects of solving feasibility problems of semidefinite programming (SDP), aka linear matrix inequalities (LMIs). Since in some SDP instances all feasible solutions have irrational entries, numerical solvers that work with rational numbers can only find an approximate solution. We study the following question: Is it possible to certify feasibility of a given SDP using an approximate solution that is sufficiently close to some exact solution? Existing approaches make the assumption that there exist rational feasible solutions (and use techniques such as rounding and lattice reduction algorithms). We propose an alternative approach that does not need this assumption. More specifically, we show how to construct a system of polynomial equations whose set of real solutions is guaranteed to have an isolated correct solution (assuming that the target exact solution is maximum-rank). This allows, in particular, for us to use algorithms from real algebraic geometry for solving systems of polynomial equations, yielding a hybrid (or symbolic-numerical) method for SDPs. We experimentally compare it with a pure symbolic method in [D. Henrion, S. Naldi, and M. Safey El Din, SIAM J. Optim., 26 (2016), pp. 2512–2539]; the hybrid method was able to certify feasibility of many SDP instances on which the aforementioned paper failed. Our approach may have further applications, such as refining an approximate solution using methods of numerical algebraic geometry for systems of polynomial equations.}, author = {Kolmogorov, Vladimir and Naldi, Simone and Zapata, Jeferson}, issn = {1095-7189}, journal = {SIAM Journal on Optimization}, number = {3}, pages = {1630--1654}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Certifying solutions of degenerate semidefinite programs}}, doi = {10.1137/24m1664691}, volume = {35}, year = {2025}, } @article{20326, abstract = {Ag2Se is a promising n-type thermoelectric material, but its performance is limited by excessive carrier concentration, compositional inhomogeneity, and phase instability, challenges rooted in a narrow homogeneity range and uncontrolled Ag+ diffusion in the superionic phase. Here, we address these issues by exploiting liquid–solid interface reactions using CdSe complexes that remove surface excess Ag to yield stoichiometric Ag2Se and generate CdSe nanodomains that inhibit Ag+ diffusion and constrain grain growth. The resulting Ag2Se-CdSe nanocomposites exhibit a reproducible, stable figure of merit (zT) of 1.04 between 300 and 390 K. Beyond demonstrating high performance, we elucidate the interfacial chemical reactions that give rise to the observed microstructure and transport properties, providing a foundation for rationally engineering interfacial chemistry to tailor transport properties across diverse thermoelectric material systems.}, author = {Liu, Yu and Kleinhanns, Tobias and Horta, Sharona and Dutkiewicz, Ewelina and Lu, Shaoqing and Spadaro, Maria Chiara and Genç, Aziz and Chen, Lei and Lim, Khak Ho and Hong, Min and Arbiol, Jordi and Ibåñez, Maria}, issn = {1520-5126}, journal = {Journal of the American Chemical Society}, number = {35}, pages = {32199--32208}, publisher = {American Chemical Society}, title = {{Liquid-solid interface reactions drive enhanced thermoelectric performance in Ag2Se}}, doi = {10.1021/jacs.5c11435}, volume = {147}, year = {2025}, } @article{20331, abstract = {Here, we present a foundational investigation of charge transport through three BODIPY-based molecules using the scanning tunneling microscope–break junction (STM-BJ) technique. We demonstrate that molecular conductance through the BODIPY core can be measured by introducing aurophilic linkers at the 2,6-positions. By varying these linkers, we systematically modulate the frontier molecular orbital energies and fine-tune transport behavior. Our experimental results are supported by DFT-based calculations, which feature a new computationally efficient correction to standard PBE-level transmission predictions. Together, these findings establish the viability of BODIPY-based systems for molecular junction applications and lay the groundwork for future studies of their single-molecule optoelectronic properties.}, author = {York, Emma and Stone, Ilana and Shi, Wanzhuo and Roy, Xavier and Venkataraman, Latha}, issn = {1530-6992}, journal = {Nano Letters}, number = {36}, pages = {13697--13702}, publisher = {American Chemical Society}, title = {{Tuning conductance in BODIPY-based single-molecule junctions}}, doi = {10.1021/acs.nanolett.5c03764}, volume = {25}, year = {2025}, } @article{20603, abstract = {We study the growth of sumsets A+B⊂S⊂G, where S does not contain an arithmetic progression of length 2k+1, and where G is a commutative group, in which every nonzero element has an order of at least 2k+1. More specifically, we show the following: if A,B⊂G are sets such that A+B does not contain an arithmetic progression of length 2k+1, then |A+B|≄|A|2k−13k−2|B|k3k−2. As an application we derive upper bounds on the cardinality of the summands in sumsets A+B+C contained in the set of t-th powers, where t≄2 is an integer. In particular, we show that min(|A|,|B|,|C|)â‰Ș(logN)4/5 for t=2, and min(|A|,|B|,|C|)â‰Șt(logN)1/2 for t≄3.}, author = {Elsholtz, Christian and Ruzsa, Imre Z. and Wurzinger, Lena}, issn = {1730-6264}, journal = {Acta Arithmetica}, pages = {289--303}, publisher = {Institute of Mathematics}, title = {{Sumset growth in progression-free sets}}, doi = {10.4064/aa250115-14-7}, volume = {220}, year = {2025}, } @unpublished{20465, abstract = {For tissues to spread, they must be deformable while maintaining their structural integrity. How these opposing requirements are balanced within spreading tissues is not yet well understood. Here, we show that keratin intermediate filaments function in epithelial spreading by adapting tissue mechanical resilience to the stresses arising in the tissue during the spreading process. By analysing the expansion of the enveloping cell layer (EVL) over the large yolk cell in early zebrafish embryos in vivo, we found that keratin network maturation in EVL cells is promoted by stresses building up within the spreading tissue. Through genetic interference and tissue rheology experiments, complemented by a vertex model with mechanochemical feedback, we demonstrate that stress-induced keratin network maturation in the EVL increases tissue viscosity, which is essential for preventing tissue rupture. Interestingly, keratins are also required in the yolk cell for mechanosensitive actomyosin network contraction and flow, the force-generating processes pulling the EVL. These dual mechanosensitive functions of keratins enable a balance between pulling force production in the yolk cell and the mechanical resilience of the EVL against stresses generated by these pulling forces, thereby ensuring uniform and robust tissue spreading.}, author = {Naik, Suyash and Keta, Yann-Edwin and Pranjic-Ferscha, Kornelija and Hannezo, Edouard B and Henkes, Silke and Heisenberg, Carl-Philipp J}, booktitle = {bioRxiv}, title = {{Keratins coordinate tissue spreading by balancing spreading forces with tissue material properties}}, doi = {10.1101/2025.02.14.638262}, year = {2025}, } @phdthesis{20735, abstract = {Left–right alternation is a defining feature of spinal locomotor circuits, yet the level of neuronal detail required to generate and maintain this pattern remains unclear. This thesis investigates how models spanning multiple levels of abstraction—from biophysically detailed Hodgkin–Huxley (HH) neurons to adaptive integrate–and–fire (I&F) formulations and synfire-chain modules—can account for the generation of fictive swimming in the spinal cord of the Xenopus laevis tadpole. The guiding hypothesis is that a small set of neuronal mechanisms is sufficient to reproduce the essential features of rhythmic alternation, and that moving between modeling scales helps distinguish core principles from biological detail. A minimal bilateral HH network comprising only four canonical neuron classes—excitatory descending interneurons (dINs), inhibitory commissural interneurons (cINs), ipsilateral inhibitory interneurons (aINs) and motoneurons—served as a biophysical proof of concept. Tuned to reproduce experimentally observed firing modes, the model demonstrated that rebound-prone dIN excitability, contralateral inhibition and modest electrical coupling are sufficient to generate stable alternating activity, even in very small networks. These results motivated the transition to simpler models capable of efficient analysis and scaling. Adaptive exponential I&F (AdEx) neurons were calibrated to physiological recordings using simulation-based inference, yielding tonic and phasic/rebound templates that preserved the key dynamical signatures of the HH model. Phase-plane analysis clarified the mechanisms underlying single-spike responses and rebound firing in dINs. At network level, the I&F models robustly reproduced left–right alternation, while highlighting constraints on synaptic kinetics and adaptation needed to avoid multi-spike responses. Finally, a synfire-chain framework provided a complementary, timing-centric perspective, demonstrating how precise spike synchrony, synaptic delays and minimal inhibitory coupling can generate alternating left–right sequences in a feedforward setting. Together, these approaches converge on a common conclusion: rebound-prone ipsilateral excitation combined with precisely timed contralateral inhibition constitutes a sufficient substrate for alternating spinal rhythms. By integrating bottom-up and top-down modeling strategies, this thesis provides a unified, extensible framework for studying spinal pattern generation. The results show that essential locomotor dynamics can be captured across multiple abstraction levels, offering both mechanistic insight and practical tools for future data-driven investigations of spinal circuit development, robustness and modulation.}, author = {Wilson, Alexia C}, issn = {2791-4585}, pages = {110}, publisher = {Institute of Science and Technology Austria}, title = {{Modelling the spinal cord of a tadpole: Exploring different ways to model the spinal cord in the Xenopus frog}}, doi = {10.15479/AT-ISTA-20735}, year = {2025}, } @unpublished{21398, abstract = {Seymour's decomposition theorem is a hallmark result in matroid theory presenting a structural characterization of the class of regular matroids. Formalization of matroid theory faces many challenges, most importantly that only a limited number of notions and results have been implemented so far. In this work, we formalize the proof of the forward (composition) direction of Seymour's theorem for regular matroids. To this end, we develop a library in Lean 4 that implements definitions and results about totally unimodular matrices, vector matroids, their standard representations, regular matroids, and 1-, 2-, and 3-sums of matrices and binary matroids given by their standard representations. Using this framework, we formally state Seymour's decomposition theorem and implement a formally verified proof of the composition direction in the setting where the matroids have finite rank and may have infinite ground sets.}, author = {Dvorak, Martin and Figueroa-Reid, Tristan and Hamadani, Rida and Hwang, Byung-Hak and Karunus, Evgenia and Kolmogorov, Vladimir and Meiburg, Alexander and Nelson, Alexander and Nelson, Peter and Sandey, Mark and Sergeev, Ivan}, booktitle = {arXiv}, title = {{Composition direction of Seymour's theorem for regular matroids — Formally verified}}, doi = {10.48550/arXiv.2509.20539}, year = {2025}, } @unpublished{20286, abstract = {Natural organisms utilize distributed actuation through their musculoskeletal systems to adapt their gait for traversing diverse terrains or to morph their bodies for varied tasks. A longstanding challenge in robotics is to emulate this capability of natural organisms, which has motivated the development of numerous soft robotic systems. However, such systems are generally optimized for a single functionality, lack the ability to change form or function on demand, or remain tethered to bulky control systems. To address these limitations, we present a framework for designing and controlling robots that utilize distributed actuation. We propose a novel building block that integrates 3D-printed bones with liquid crystal elastomer (LCE) muscles as lightweight actuators, enabling the modular assembly of musculoskeletal robots. We developed LCE rods that contract in response to infrared radiation, thereby providing localized, untethered control over the distributed skeletal network and producing global deformations of the robot. To fully capitalize on the extensive design space, we introduce two computational tools: one for optimizing the robot's skeletal graph to achieve multiple target deformations, and another for co-optimizing skeletal designs and control gaits to realize desired locomotion. We validate our framework by constructing several robots that demonstrate complex shape morphing, diverse control schemes, and environmental adaptability. Our system integrates advances in modular material building, untethered and distributed control, and computational design to introduce a new generation of robots that brings us closer to the capabilities of living organisms.}, author = {Bhargava, Manas and Hiraki, Takefumi and Strugaru, Irina-Malina and Zhang, Yuhan and Piovarci, Michael and Daraio, Chiara and Iwai, Daisuke and Bickel, Bernd}, booktitle = {arXiv}, title = {{Computational design and fabrication of modular robots with untethered control}}, doi = {10.48550/arXiv.2508.05410}, year = {2025}, } @phdthesis{20371, abstract = {Quantum mechanics reveals a world that defies classical determinism, where uncertainty, superposition, and fluctuations are fundamental aspects. Engineering devices that harness these quantum features requires not only precision, but also a deep understanding of how they interact with their surrounding environment. Superconducting circuits, which exploit macroscopic quantum coherence in low-loss superconducting materials, provide a scalable platform for implementing such systems. Among the critical elements in these circuits, superinductors—high-impedance, dissipation-free inductive components—play a central role by suppressing charge fluctuations. They allow quantum states to be delocalized in phase space, protect qubits from environmental noise, and facilitate access to phenomena such as dual Josephson physics and ultra-strong coupling regimes. This thesis explores two complementary implementations of high-impedance circuits: geometric superinductors, demonstrating that high impedance can be achieved beyond kinetic inductance, and Josephson junction chains, used to investigate both microwave mode properties and DC transport across the superconductor-to-insulator transition. Part I addresses geometric superinductors. Contrary to the common belief that high-impedance superconducting circuits require kinetic inductance, we demonstrate that purely geometric designs can achieve characteristic impedance exceeding the resistance quantum. By exploiting mutual coupling between adjacent turns, coil-based inductors achieve enhanced self-inductance, creating a reliable platform for qubits and resonators. Modeling, simulation, fabrication, and characterization confirm that these elements behave as superinductor. With low loss, high linearity, and minimal stray capacitance, these elements are reproducible, free of uncontrolled tunneling events, and capable of strong magnetic coupling. This establishes geometric superinductors as robust, single-wave-function superconducting devices suitable for hardware protected qubits and hybrid systems. Part II presents classical numerical simulations of a Quantum Phase Slip circuit to study dual Shapiro steps. The circuit consists of an ideal Quantum Phase Slip element embedded in a resistive-inductive environment with a parasitic capacitance. Part III extends the investigation of high characteristic-impedance circuit elements to one-dimensional Josephson junction chains, which act as a quantum simulator for many-body physics and the superconductor–insulator transition. Different devices are realized on both sides of the DC phase transition, showing either a supercurrent branch or Coulomb blockade at zero bias. The effect of the crossover on microwave modes, however, remains insufficiently investigated. Studying these modes provides insight into the interplay between disorder and phase-slip events. Small differences in circuit component sizes determine which side of the transition a device falls on, making these results relevant not only for fundamental understanding but also for the design of quantum devices, emphasizing the crucial role of the electromagnetic environment in stabilizing and controlling fragile quantum states. Together, these results illustrate how carefully engineered high characteristic-impedance elements provide a link between macroscopic circuits and the inherently uncertain quantum world, enabling experiments that probe, control, and ultimately exploit quantum fluctuations for applications in quantum information, metrology, solid state physics and beyond. }, author = {Trioni, Andrea}, isbn = {978-3-99078-067-1}, issn = {2663-337X}, pages = {202}, publisher = {Institute of Science and Technology Austria}, title = {{High-impedance quantum circuits for mesoscopic physics: Geometric superinductors and insulating Josephson Chains}}, doi = {10.15479/AT-ISTA-20371}, year = {2025}, } @inproceedings{20008, abstract = {We study the complexity of a class of promise graph homomorphism problems. For a fixed graph H, the H-colouring problem is to decide whether a given graph has a homomorphism to H. By a result of Hell and NeĆĄetƙil, this problem is NP-hard for any non-bipartite loop-less graph H. Brakensiek and Guruswami [SODA 2018] conjectured the hardness extends to promise graph homomorphism problems as follows: fix a pair of non-bipartite loop-less graphs G, H such that there is a homomorphism from G to H, it is NP-hard to distinguish between graphs that are G-colourable and those that are not H-colourable. We confirm this conjecture in the cases when both G and H are 4-colourable. This is a common generalisation of previous results of Khanna, Linial, and Safra [Comb. 20(3): 393-415 (2000)] and of Krokhin and OprĆĄal [FOCS 2019]. The result is obtained by combining the algebraic approach to promise constraint satisfaction with methods of topological combinatorics and equivariant obstruction theory.}, author = {Avvakumov, Sergey and FilakovskĂœ, Marek and OprĆĄal, Jakub and Tasinato, Gianluca and Wagner, Uli}, booktitle = {Proceedings of the 57th Annual ACM Symposium on Theory of Computing}, isbn = {9798400715105}, issn = {0737-8017}, location = {Prague, Czechia}, pages = {72--83}, publisher = {Association for Computing Machinery}, title = {{Hardness of 4-colouring G-colourable graphs}}, doi = {10.1145/3717823.3718154}, year = {2025}, } @article{18112, abstract = {It is conjectured that the only integrable metrics on the two-dimensional torus are Liouville metrics. In this paper, we study a deformative version of this conjecture: we consider integrable deformations of a non-flat Liouville metric in a conformal class and show that for a fairly large class of such deformations, the deformed metric is again Liouville. The principal idea of the argument is that the preservation of rational invariant tori in the foliation of the phase space forces a linear combination on the Fourier coefficients of the deformation to vanish. Showing that the resulting linear system is non-degenerate will then yield the claim. Since our method of proof immediately carries over to higher dimensional tori, we obtain analogous statements in this more general case. To put our results in perspective, we review existing results about integrable metrics on the torus.}, author = {Henheik, Sven Joscha}, issn = {1469-4417}, journal = {Ergodic Theory and Dynamical Systems}, number = {2}, pages = {467--503}, publisher = {Cambridge University Press}, title = {{Deformational rigidity of integrable metrics on the torus}}, doi = {10.1017/etds.2024.48}, volume = {45}, year = {2025}, } @article{19001, abstract = {We consider two Hamiltonians that are close to each other, H1≈H2, and analyze the time-decay of the corresponding Loschmidt echo M(t):=|⟚ψ0,eitH2e−itH1ψ0⟩|2 that expresses the effect of an imperfect time reversal on the initial state ψ0. Our model Hamiltonians are deformed Wigner matrices that do not share a common eigenbasis. The main tools for our results are two-resolvent laws for such H1 and H2.}, author = {Erdös, LĂĄszlĂł and Henheik, Sven Joscha and Kolupaiev, Oleksii}, issn = {1573-0530}, journal = {Letters in Mathematical Physics}, publisher = {Springer Nature}, title = {{Loschmidt echo for deformed Wigner matrices}}, doi = {10.1007/s11005-025-01904-5}, volume = {115}, year = {2025}, }