@inproceedings{JaegerSutterTockhornetal.2022, author = {J{\"a}ger, Klaus and Sutter, Johannes and Tockhorn, Philipp and Hammerschmidt, Martin and Schneider, Philipp-Immanuel and Albrecht, Steve and Becker, Christiane}, title = {Improving perovskite/silicon tandem solar cells with optical simulations}, volume = {PC12150}, booktitle = {Proc. SPIE}, doi = {10.1117/12.2621255}, pages = {PC1215001}, year = {2022}, language = {en} } @article{AvalosOvandoSantiagoMovsesyanetal.2022, author = {Avalos-Ovando, Oscar and Santiago, Eva Yazmin and Movsesyan, Artur and Kong, Xiang-Tian and Yu, Peng and Besteiro, Lucas V. and Khosravi Khorashad, Larousse and Okamoto, Hiromi and Slocik, Joseph M. and Correa-Duarte, Miguel and Comesana-Hermo, Miguel and Liedl, Tim and Markovich, Gil and Burger, Sven and Govorov, Alexander O.}, title = {Chiral Bioinspired Plasmonics: A Paradigm Shift for Optical Activity and Photochemistry}, volume = {9}, journal = {ACS Photon.}, doi = {10.1021/acsphotonics.2c00445}, pages = {2219}, year = {2022}, language = {en} } @article{BremerJimenezThieleetal.2022, author = {Bremer, Lucas and Jimenez, Carlos and Thiele, Simon and Weber, Ksenia and Huber, Tobias and Rodt, Sven and Herkommer, Alois and Burger, Sven and H{\"o}fling, Sven and Giessen, Harald and Reitzenstein, Stephan}, title = {Numerical optimization of single-mode fiber- coupled single-photon sources based on semiconductor quantum dots}, volume = {30}, journal = {Opt. Express}, arxiv = {http://arxiv.org/abs/2202.09562}, doi = {10.1364/OE.456777}, pages = {15913}, year = {2022}, language = {en} } @article{DassKuenPosnjaketal.2022, author = {Dass, Mihir and Kuen, Lilli and Posnjak, Gregor and Burger, Sven and Liedl, Tim}, title = {Visible wavelength spectral tuning of absorption and circular dichroism of DNA-assembled Au/Ag core-shell nanorod assemblies}, volume = {3}, journal = {Mater. Adv.}, doi = {10.1039/D1MA01211H}, pages = {3438}, year = {2022}, language = {en} } @article{PlockAndrleBurgeretal.2022, author = {Plock, Matthias and Andrle, Kas and Burger, Sven and Schneider, Philipp-Immanuel}, title = {Bayesian Target-Vector Optimization for Efficient Parameter Reconstruction}, volume = {5}, journal = {Adv. Theory Simul.}, arxiv = {http://arxiv.org/abs/2202.11559}, doi = {10.1002/adts.202200112}, pages = {2200112}, year = {2022}, language = {en} } @article{VolkovaHeupelTrofimovetal.2022, author = {Volkova, Kseniia and Heupel, Julia and Trofimov, Sergei and Betz, Fridtjof and Colom, R{\´e}mi and MacQueen, Rowan W. and Akhundzada, Sapida and Reginka, Meike and Ehresmann, Arno and Reithmeier, Johann Peter and Burger, Sven and Popov, Cyril and Naydenov, Boris}, title = {Optical and Spin Properties of NV Center Ensembles in Diamond Nano-Pillars}, volume = {12}, journal = {Nanomaterials}, doi = {10.3390/nano12091516}, pages = {1516}, year = {2022}, language = {en} } @article{WangVannucciBurgeretal.2022, author = {Wang, Yujing and Vannucci, Luca and Burger, Sven and Gregersen, Niels}, title = {Near-unity efficiency in ridge waveguide-based, on-chip single-photon sources}, volume = {2}, journal = {Mater. Quantum Technol.}, arxiv = {http://arxiv.org/abs/2207.02665}, doi = {10.1088/2633-4356/aca8e8}, pages = {045004}, year = {2022}, language = {en} } @article{LopezFraguasBinkowskiBurgeretal.2022, author = {Lopez-Fraguas, Eduardo and Binkowski, Felix and Burger, Sven and Hagedorn, Sylvia and Garcia-Camara, Braulio and Vergaz, Ricardo and Becker, Christiane and Manley, Phillip}, title = {Tripling the light extraction efficiency of a deep ultraviolet LED using a nanostructured p-contact}, volume = {12}, journal = {Sci. Rep.}, doi = {10.1038/s41598-022-15499-7}, pages = {11480}, year = {2022}, language = {en} } @misc{BetzColomBurgeretal.2022, author = {Betz, Fridtjof and Colom, Remi and Burger, Sven and Naydenov, Boris}, title = {Scripts for quantifying the effect of diamond nano-pillars on the fluorescence of NV centers}, journal = {Zenodo}, doi = {10.5281/zenodo.6558815}, year = {2022}, language = {en} } @article{BeronVeraOlascoagaHelfmannetal.2023, author = {Beron-Vera, Francisco Javier and Olascoaga, Maria Josefina and Helfmann, Luzie and Miron, Philippe}, title = {Sampling-Dependent Transition Paths of Iceland-Scotland Overflow Water}, volume = {53}, journal = {Journal of Physical Oceanography}, number = {4}, arxiv = {http://arxiv.org/abs/2208.09499}, doi = {10.1175/JPO-D-22-0172.1}, pages = {1151 -- 1160}, year = {2023}, abstract = {In this note, we apply Transition Path Theory (TPT) from Markov chains to shed light on the problem of Iceland-Scotland Overflow Water (ISOW) equatorward export. A recent analysis of observed trajectories of submerged floats demanded revision of the traditional abyssal circulation theory, which postulates that ISOW should steadily flow along a deep boundary current (DBC) around the subpolar North Atlantic prior to exiting it. The TPT analyses carried out here allow to focus the attention on the portions of flow from the origin of ISOW to the region where ISOW exits the subpolar North Atlantic and suggest that insufficient sampling may be biasing the aforementioned demand. The analyses, appropriately adapted to represent a continuous input of ISOW, are carried out on three time-homogeneous Markov chains modeling the ISOW flow. One is constructed using a high number of simulated trajectories homogeneously covering the flow domain. The other two use much fewer trajectories which heterogeneously cover the domain. The trajectories in the latter two chains are observed trajectories or simulated trajectories subsampled at the observed frequency. While the densely sampled chain supports a well-defined DBC, the more heterogeneously sampled chains do not, irrespective of whether observed or simulated trajectories are used. Studying the sampling sensitivity of the Markov chains, we can give recommendations for enlarging the existing float dataset to improve the significance of conclusions about time-asymptotic aspects of the ISOW circulation.}, language = {en} } @article{BartelsFisikopoulosWeiser2023, author = {Bartels, Tinko and Fisikopoulos, Vissarion and Weiser, Martin}, title = {Fast Floating-Point Filters for Robust Predicates}, volume = {63}, journal = {BIT Numerical Mathematics}, arxiv = {http://arxiv.org/abs/2208.00497}, doi = {10.1007/s10543-023-00975-x}, year = {2023}, abstract = {Geometric predicates are at the core of many algorithms, such as the construction of Delaunay triangulations, mesh processing and spatial relation tests. These algorithms have applications in scientific computing, geographic information systems and computer-aided design. With floating-point arithmetic, these geometric predicates can incur round-off errors that may lead to incorrect results and inconsistencies, causing computations to fail. This issue has been addressed using a combination of exact arithmetic for robustness and floating-point filters to mitigate the computational cost of exact computations. The implementation of exact computations and floating-point filters can be a difficult task, and code generation tools have been proposed to address this. We present a new C++ meta-programming framework for the generation of fast, robust predicates for arbitrary geometric predicates based on polynomial expressions. We combine and extend different approaches to filtering, branch reduction, and overflow avoidance that have previously been proposed. We show examples of how this approach produces correct results for data sets that could lead to incorrect predicate results with naive implementations. Our benchmark results demonstrate that our implementation surpasses state-of-the-art implementations.}, language = {en} } @article{BinkowskiBetzHammerschmidtetal.2022, author = {Binkowski, Felix and Betz, Fridtjof and Hammerschmidt, Martin and Schneider, Philipp-Immanuel and Zschiedrich, Lin and Burger, Sven}, title = {Computation of eigenfrequency sensitivities using Riesz projections for efficient optimization of nanophotonic resonators}, volume = {5}, journal = {Commun. Phys.}, arxiv = {http://arxiv.org/abs/2203.11101}, doi = {10.1038/s42005-022-00977-1}, pages = {202}, year = {2022}, language = {en} } @article{TockhornSutterCruzetal.2022, author = {Tockhorn, Philipp and Sutter, Johannes and Cruz, Alexandros and Wagner, Philipp and J{\"a}ger, Klaus and Yoo, Danbi and Lang, Felix and Grischek, Max and Li, Bor and Li, Jinzhao and Shargaieva, Oleksandra and Unger, Eva and Al-Ashouri, Amran and K{\"o}hnen, Eike and Stolterfoth, Martin and Neher, Dieter and Schlatmann, Rutger and Rech, Bernd and Stannowski, Bernd and Albrecht, Steve and Becker, Christiane}, title = {Nano-optical designs for high-efficiency monolithic perovskite-silicon tandem solar cells}, volume = {17}, journal = {Nat. Nanotechnol.}, doi = {10.1038/s41565-022-01228-8}, pages = {1214}, year = {2022}, language = {en} } @article{MovsesyanSantiagoBurgeretal.2022, author = {Movsesyan, Artur and Santiago, Eva Yazmin and Burger, Sven and Correa-Duarte, Miguel and Besteiro, Lucas V. and Wang, Zhiming and Govorov, Alexander O.}, title = {Plasmonic nanocrystals with complex shapes for photocatalysis and growth: Contrasting anisotropic hot-electron generation with the photothermal effect}, volume = {10}, journal = {Adv. Opt. Mater.}, arxiv = {http://arxiv.org/abs/2203.00930}, doi = {10.1002/adom.202102663}, pages = {2102663}, year = {2022}, language = {en} } @misc{ColomBinkowskiBetzetal.2022, author = {Colom, Remi and Binkowski, Felix and Betz, Fridtjof and Kivshar, Yuri and Burger, Sven}, title = {Source code and simulation results for nanoantennas supporting an enhanced Purcell factor due to interfering resonances}, journal = {Zenodo}, doi = {10.5281/zenodo.6565850}, year = {2022}, language = {en} } @article{KlusDjurdjevacConrad2022, author = {Klus, Stefan and Djurdjevac Conrad, Natasa}, title = {Koopman-based spectral clustering of directed and time-evolving graphs}, volume = {33}, journal = {Journal of Nonlinear Science}, arxiv = {http://arxiv.org/abs/2204.02951}, doi = {10.1007/s00332-022-09863-0}, pages = {8}, year = {2022}, abstract = {While spectral clustering algorithms for undirected graphs are well established and have been successfully applied to unsupervised machine learning problems ranging from image segmentation and genome sequencing to signal processing and social network analysis, clustering directed graphs remains notoriously difficult. Two of the main challenges are that the eigenvalues and eigenvectors of graph Laplacians associated with directed graphs are in general complex-valued and that there is no universally accepted definition of clusters in directed graphs. We first exploit relationships between the graph Laplacian and transfer operators and in particular between clusters in undirected graphs and metastable sets in stochastic dynamical systems and then use a generalization of the notion of metastability to derive clustering algorithms for directed and time-evolving graphs. The resulting clusters can be interpreted as coherent sets, which play an important role in the analysis of transport and mixing processes in fluid flows.}, language = {en} } @article{TillmannJaegerKarsentietal.2022, author = {Tillmann, Peter and J{\"a}ger, Klaus and Karsenti, Asher and Kreinin, Lev and Becker, Christiane}, title = {Model-Chain Validation for Estimating the Energy Yield of Bifacial Perovskite/Silicon Tandem Solar Cells}, volume = {6}, journal = {Sol. RRL}, doi = {10.1002/solr.202200079}, pages = {2200079}, year = {2022}, language = {en} } @article{EngelOliconMendezWehlitzetal.2024, author = {Engel, Maximilian and Olic{\´o}n-M{\´e}ndez, Guillermo and Wehlitz, Nathalie and Winkelmann, Stefanie}, title = {Synchronization and random attractors in reaction jump processes}, journal = {Journal of Dynamics and Differential Equations}, arxiv = {http://arxiv.org/abs/2207.00602}, doi = {10.1007/s10884-023-10345-4}, year = {2024}, abstract = {This work explores a synchronization-like phenomenon induced by common noise for continuous-time Markov jump processes given by chemical reaction networks. Based on Gillespie's stochastic simulation algorithm, a corresponding random dynamical system is formulated in a two-step procedure, at first for the states of the embedded discrete-time Markov chain and then for the augmented Markov chain including random jump times. We uncover a time-shifted synchronization in the sense that—after some initial waiting time—one trajectory exactly replicates another one with a certain time delay. Whether or not such a synchronization behavior occurs depends on the combination of the initial states. We prove this partial time-shifted synchronization for the special setting of a birth-death process by analyzing the corresponding two-point motion of the embedded Markov chain and determine the structure of the associated random attractor. In this context, we also provide general results on existence and form of random attractors for discrete-time, discrete-space random dynamical systems.}, language = {en} } @misc{SagnolHegeWeiser2016, author = {Sagnol, Guillaume and Hege, Hans-Christian and Weiser, Martin}, title = {Using sparse kernels to design computer experiments with tunable precision}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-59605}, year = {2016}, abstract = {Statistical methods to design computer experiments usually rely on a Gaussian process (GP) surrogate model, and typically aim at selecting design points (combinations of algorithmic and model parameters) that minimize the average prediction variance, or maximize the prediction accuracy for the hyperparameters of the GP surrogate. In many applications, experiments have a tunable precision, in the sense that one software parameter controls the tradeoff between accuracy and computing time (e.g., mesh size in FEM simulations or number of Monte-Carlo samples). We formulate the problem of allocating a budget of computing time over a finite set of candidate points for the goals mentioned above. This is a continuous optimization problem, which is moreover convex whenever the tradeoff function accuracy vs. computing time is concave. On the other hand, using non-concave weight functions can help to identify sparse designs. In addition, using sparse kernel approximations drastically reduce the cost per iteration of the multiplicative weights updates that can be used to solve this problem.}, language = {en} } @misc{WitzigBeckenbachEifleretal.2016, author = {Witzig, Jakob and Beckenbach, Isabel and Eifler, Leon and Fackeldey, Konstantin and Gleixner, Ambros and Grever, Andreas and Weber, Marcus}, title = {Mixed-Integer Programming for Cycle Detection in Non-reversible Markov Processes}, issn = {1438-0064}, doi = {10.1137/16M1091162}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-60353}, year = {2016}, abstract = {In this paper, we present a new, optimization-based method to exhibit cyclic behavior in non-reversible stochastic processes. While our method is general, it is strongly motivated by discrete simulations of ordinary differential equations representing non-reversible biological processes, in particular molecular simulations. Here, the discrete time steps of the simulation are often very small compared to the time scale of interest, i.e., of the whole process. In this setting, the detection of a global cyclic behavior of the process becomes difficult because transitions between individual states may appear almost reversible on the small time scale of the simulation. We address this difficulty using a mixed-integer programming model that allows us to compute a cycle of clusters with maximum net flow, i.e., large forward and small backward probability. For a synthetic genetic regulatory network consisting of a ring-oscillator with three genes, we show that this approach can detect the most productive overall cycle, outperforming classical spectral analysis methods. Our method applies to general non-equilibrium steady state systems such as catalytic reactions, for which the objective value computes the effectiveness of the catalyst.}, language = {en} } @article{WitzigBeckenbachEifleretal.2018, author = {Witzig, Jakob and Beckenbach, Isabel and Eifler, Leon and Fackeldey, Konstantin and Gleixner, Ambros and Grever, Andreas and Weber, Marcus}, title = {Mixed-Integer Programming for Cycle Detection in Non-reversible Markov Processes}, volume = {16}, journal = {Multiscale Modeling and Simulation}, number = {1}, issn = {1438-0064}, doi = {10.1137/16M1091162}, pages = {248 -- 265}, year = {2018}, abstract = {In this paper, we present a new, optimization-based method to exhibit cyclic behavior in non-reversible stochastic processes. While our method is general, it is strongly motivated by discrete simulations of ordinary differential equations representing non-reversible biological processes, in particular molecular simulations. Here, the discrete time steps of the simulation are often very small compared to the time scale of interest, i.e., of the whole process. In this setting, the detection of a global cyclic behavior of the process becomes difficult because transitions between individual states may appear almost reversible on the small time scale of the simulation. We address this difficulty using a mixed-integer programming model that allows us to compute a cycle of clusters with maximum net flow, i.e., large forward and small backward probability. For a synthetic genetic regulatory network consisting of a ring-oscillator with three genes, we show that this approach can detect the most productive overall cycle, outperforming classical spectral analysis methods. Our method applies to general non-equilibrium steady state systems such as catalytic reactions, for which the objective value computes the effectiveness of the catalyst.}, language = {en} }