@inproceedings{63890,
  abstract     = {{The computation of highly contracted electron repulsion integrals (ERIs) is essential to achieve quantum accuracy in atomistic simulations based on quantum mechanics. Its growing computational demands make energy efficiency a critical concern. Recent studies demonstrate FPGAs’ superior performance and energy efficiency for computing primitive ERIs, but the computation of highly contracted ERIs introduces significant algorithmic complexity and new design challenges for FPGA acceleration.In this work, we present SORCERI, the first streaming overlay acceleration for highly contracted ERI computations on FPGAs. SORCERI introduces a novel streaming Rys computing unit to calculate roots and weights of Rys polynomials on-chip, and a streaming contraction unit for the contraction of primitive ERIs. This shifts the design bottleneck from limited CPU-FPGA communication bandwidth to available FPGA computation resources. To address practical deployment challenges for a large number of quartet classes, we design three streaming overlays, together with an efficient memory transpose optimization, to cover the 21 most commonly used quartet classes in realistic atomistic simulations. To address the new computation constraints, we use flexible calculation stages with a free-running streaming architecture to achieve high DSP utilization and good timing closure.Experiments demonstrate that SORCERI achieves an average 5.96x, 1.99x, and 1.16x better performance per watt than libint on a 64-core AMD EPYC 7713 CPU, libintx on an Nvidia A40 GPU, and SERI, the prior best-performing FPGA design for primitive ERIs. Furthermore, SORCERI reaches a peak throughput of 44.11 GERIS (109 ERIs per second) that is 1.52x, 1.13x, and 1.93x greater than libint, libintx and SERI, respectively. SORCERI will be released soon at https://github.com/SFU-HiAccel/SORCERI.}},
  author       = {{Stachura, Philip and Wu, Xin and Plessl, Christian and Fang, Zhenman}},
  booktitle    = {{Proceedings of the 2026 ACM/SIGDA International Symposium on Field Programmable Gate Arrays (FPGA '26)}},
  isbn         = {{9798400720796}},
  keywords     = {{electron repulsion integrals, quantum chemistry, atomistic simulation, overlay architecture, fpga acceleration}},
  pages        = {{224--234}},
  publisher    = {{Association for Computing Machinery}},
  title        = {{{SORCERI: Streaming Overlay Acceleration for Highly Contracted Electron Repulsion Integral Computations in Quantum Chemistry}}},
  doi          = {{10.1145/3748173.3779198}},
  year         = {{2026}},
}

@inproceedings{65101,
  abstract     = {{Various methods to measure the dynamic behavior of particles require the calculation of autocorrelation functions. For this purpose, fast multi-tau correlators have been developed in dedicated hardware, in software, and on FPGAs. However, for methods such as X-ray Photon Correlation Spectroscopy (XPCS), which requires to calculate the autocorrelation function independently for hundreds of thousands to millions of pixels from high-resolution detectors, current approaches rely on offline processing after data acquisition. Moreover, the internal pipeline state of so many independent correlators is far too large to keep it on-chip. In this work, we propose a design approach on FPGAs, where pipeline contexts are stored in off-chip HBM memory. Each compute unit iteratively loads the state for a single pixel, processes a short time series for this pixel, and afterwards writes back the context in a dataflow pipeline. We have implemented the required compute kernels with Vitis HLS and analyze resulting designs on an Alveo U280 card. The design achieves the expected performance and for the first time provides sufficient throughput for current high-end detectors used in XPCS.}},
  author       = {{Tareen, Abdul Rehman and Plessl, Christian and Kenter, Tobias}},
  booktitle    = {{2025 International Conference on Field Programmable Technology (ICFPT)}},
  publisher    = {{IEEE}},
  title        = {{{Fast Multi-Tau Correlators on FPGA with Context Switching From and to High- Bandwidth Memory}}},
  doi          = {{10.1109/icfpt67023.2025.00027}},
  year         = {{2026}},
}

@article{65629,
  author       = {{Iannuzzi, Marcella and Wilhelm, Jan and Stein, Frederick and Bussy, Augustin and Elgabarty, Hossam and Golze, Dorothea and Hehn, Anna-Sophia and Graml, Maximilian and Marek, Stepan and Gökmen, Beliz Sertcan and Schran, Christoph and Forbert, Harald and Khaliullin, Rustam Z. and Kozhevnikov, Anton and Taillefumier, Mathieu and Meli, Rocco and Rybkin, Vladimir V. and Brehm, Martin and Schade, Robert and Schütt, Ole and Pototschnig, Johann V. and Mirhosseini, Hossein and Knüpfer, Andreas and Marx, Dominik and Krack, Matthias and Hutter, Jürg and Kühne, Thomas D.}},
  issn         = {{1520-6106}},
  journal      = {{The Journal of Physical Chemistry B}},
  number       = {{4}},
  pages        = {{1237--1310}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{The CP2K Program Package Made Simple}}},
  doi          = {{10.1021/acs.jpcb.5c05851}},
  volume       = {{130}},
  year         = {{2026}},
}

@article{66665,
  abstract     = {{Multimode quantum light has promising applications in many areas of physics, such as quantum communications and quantum computing. However, its multimode nature also makes it challenging to measure its properties. Recently [I. Barakat et al., Optica Quantum 3, 36 (2025)], a technique for the simultaneous measurement of squeezing of multiple broadband modes based on a phase-sensitive amplification approach was experimentally implemented using a setup that effectively corresponds to an SU(1,1) interferometer. Here, we aim to provide a complete theoretical analysis of the modal structure of (generally unbalanced) SU(1,1) interferometers and a detailed theoretical formal derivation of the framework for this technique. Utilizing the joint Schmidt decomposition of the transfer functions, we investigate the shape and phase profiles of the modes of the SU(1,1) interferometer and its components [parametric down-conversion (PDC) sections] for different parametric gain regimes. We discover a complicated interplay between the PDC modes and the modes of the entire interferometer, and analyze it by using their overlap coefficients as a similarity measure. Finally, we develop a rigorous processing method for the aforementioned multimode squeezing measurement technique and discuss necessary approximations to make this method experimentally feasible.}},
  author       = {{Scharwald, Dennis and Sharapova, Polina}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Characterization of spatial Schmidt modes in high-gain SU(1,1) interferometers}}},
  doi          = {{10.1103/ph64-ts39}},
  volume       = {{8}},
  year         = {{2026}},
}

@unpublished{64071,
  abstract     = {{Stimulated by the renewed interest and recent developments in semi-empirical quantum chemical (SQC) methods for noncovalent interactions, we examine the properties of liquid water at ambient conditions by means of molecular dynamics (MD) simulations, both with the conventional NDDO-type (neglect of diatomic differential overlap) methods, e.g. AM1 and PM6, and with DFTB-type (density-functional tight-binding) methods, e.g. DFTB2 and GFN-xTB. Besides the original parameter sets, some specifically reparametrized SQC methods (denoted as AM1-W, PM6-fm, and DFTB2-iBi) targeting various smaller water systems ranging from molecular clusters to bulk are considered as well. The quality of these different SQC methods for describing liquid water properties at ambient conditions are assessed by comparison to well-established experimental data and also to BLYP-D3 density functional theory-based ab initio MD simulations. Our analyses reveal that static and dynamics properties of bulk water are poorly described by all considered SQC methods with the original parameters, regardless of the underlying theoretical models, with most of the methods suffering from too weak hydrogen bonds and hence predicting a far too fluid water with highly distorted hydrogen bond kinetics. On the other hand, the reparametrized force-matchcd PM6-fm method is shown to be able to quantitatively reproduce the static and dynamic features of liquid water, and thus can be used as a computationally efficient alternative to electronic structure-based MD simulations for liquid water that requires extended length and time scales. DFTB2-iBi predicts a slightly overstructured water with reduced fluidity, whereas AM1-W gives an amorphous ice-like structure for water at ambient conditions.}},
  author       = {{Wu, Xin and Elgabarty, Hossam and Alizadeh, Vahideh and Henao Aristizabal, Andres and Zysk, Frederik and Plessl, Christian and Ehlert, Sebastian and Hutter, Jürg and Kühne, Thomas D.}},
  title        = {{{Benchmarking semi-empirical quantum chemical methods on liquid water}}},
  year         = {{2025}},
}

@article{61246,
  abstract     = {{<jats:title>Abstract</jats:title>
          <jats:p>The time-dependent one-dimensional nonlinear Schrödinger equation (NLSE) is solved numerically by a hybrid pseudospectral-variational quantum algorithm that connects a pseudospectral step for the Hamiltonian term with a variational step for the nonlinear term. The Hamiltonian term is treated as an integrating factor by forward and backward Fourier transforms, which are here carried out classically. This split allows us to avoid higher-order time integration schemes, to apply a first-order explicit time stepping for the remaining nonlinear NLSE term in a variational algorithm block, and thus to avoid numerical instabilities. We demonstrate that the analytical solution is reproduced with a small root mean square error for a long time interval over which a nonlinear soliton propagates significantly forward in space while keeping its shape. We analyze the accuracy and complexity of the quantum algorithm, the expressibility of the ansatz circuit and compare it with classical approaches. Furthermore, we investigate the influence of algorithm parameters on the accuracy of the results, including the temporal step width and the depth of the quantum circuit.</jats:p>}},
  author       = {{Köcher, Nikolas and Rose, Hendrik and Bharadwaj, Sachin S. and Schumacher, Jörg and Schumacher, Stefan}},
  issn         = {{2045-2322}},
  journal      = {{Scientific Reports}},
  number       = {{1}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Numerical solution of nonlinear Schrödinger equation by a hybrid pseudospectral-variational quantum algorithm}}},
  doi          = {{10.1038/s41598-025-05660-3}},
  volume       = {{15}},
  year         = {{2025}},
}

@article{61249,
  author       = {{Ai, Qiang and Wingenbach, Jan and Yang, Xinmiao and Wei, Jing and Hatzopoulos, Zaharias and Savvidis, Pavlos G. and Schumacher, Stefan and Ma, Xuekai and Gao, Tingge}},
  issn         = {{2331-7019}},
  journal      = {{Physical Review Applied}},
  number       = {{2}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Optically and remotely controlling localization of exciton-polariton condensates in a potential lattice}}},
  doi          = {{10.1103/physrevapplied.23.024029}},
  volume       = {{23}},
  year         = {{2025}},
}

@article{61351,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>The interaction of water molecules with semiconductor surfaces is relevant to various optoelectronic phenomena and physicochemical processes. Despite advances in fundamental understanding of water‐exposed surfaces, the detailed time‐ and energy‐resolved behavior of excited electrons remains largely unexplored. Here, the effects of water exposure on the near‐surface electron dynamics of phosphorus‐terminated p(2×2)/c(4×2)‐reconstructed indium phosphide (100) (P‐rich InP) are studied experimentally and matched to theoretical calculations. The P‐rich InP surface, consisting of H‐passivated P‐dimers, serves as a model for other P‐containing III‐V semiconductors such as gallium phosphide (GaP) or aluminum indium phosphide (AlInP). Electron dynamics near the surface are probed with femtosecond resolution using time‐resolved two‐photon photoemission (tr‐2PPE), a pump‐probe spectroscopic technique. Pulsed water exposure preserves electronic states and significantly increases lifetimes at the conduction band minimum (CBM). Density‐functional theory (DFT) calculations attribute these findings to suppression of surface vibrational modes in the top P‐layer by water exposure, reducing electronic transition probabilities of near‐band‐gap surface states. The results suggest that many near‐surface state lifetimes reported in ultra‐high vacuum may change significantly upon electrolyte exposure. These states may thus contribute more strongly to surface reactions than traditionally assumed. Demonstrating this effect for the technologically relevant P‐rich InP surface opens new opportunities in this underexplored area of surface electrochemistry.</jats:p>}},
  author       = {{Diederich, Jonathan and Paszuk, Agnieszka and Ruiz Alvarado, Isaac Azahel and Krenz, Marvin and Zare Pour, Mohammad Amin and Babu, Diwakar Suresh and Velazquez Rojas, Jennifer and Höhn, Christian and Gao, Yuying and Schwarzburg, Klaus and Ostheimer, David and Eichberger, Rainer and Schmidt, Wolf Gero and Hannappel, Thomas and de Krol, Roel van and Friedrich, Dennis}},
  issn         = {{2196-7350}},
  journal      = {{Advanced Materials Interfaces}},
  number       = {{16}},
  publisher    = {{Wiley}},
  title        = {{{Ultrafast Electron Dynamics at the Water‐Modified InP(100) Surface}}},
  doi          = {{10.1002/admi.202500463}},
  volume       = {{12}},
  year         = {{2025}},
}

@article{61356,
  abstract     = {{<jats:p>First-principles calculations reveal how topological defects in semiconducting carbon nanotubes trap triplet excitons and enable single-photon emission at telecom wavelengths, offering new insights into their potential for photonic devices.</jats:p>}},
  author       = {{Biktagirov, Timur and Gerstmann, Uwe and Schmidt, Wolf Gero}},
  issn         = {{2040-3364}},
  journal      = {{Nanoscale}},
  number       = {{11}},
  pages        = {{6884--6891}},
  publisher    = {{Royal Society of Chemistry (RSC)}},
  title        = {{{Topological defects in semiconducting carbon nanotubes as triplet exciton traps and single-photon emitters}}},
  doi          = {{10.1039/d4nr03904a}},
  volume       = {{17}},
  year         = {{2025}},
}

@article{58519,
  abstract     = {{<jats:p>A unified theoretical approach to describe the properties of multimode squeezed light generated in a lossy medium is presented. This approach is valid for Markovian environments and includes both a model of discrete losses based on the beamsplitter approach and a generalized continuous loss model based on the spatial Langevin equation. For an important class of Gaussian states, we derive master equations for the second-order correlation functions and illustrate their solution for both frequency-independent and frequency-dependent losses. Studying the mode structure, we demonstrate that in a lossy environment no broadband basis without quadrature correlations between the different broadband modes exists. Therefore, various techniques and strategies to introduce broadband modes can be considered. We show that the Mercer expansion and the Williamson-Euler decomposition do not provide modes in which the maximal squeezing contained in the system can be measured. In turn, we find a new broadband basis that maximizes squeezing in the lossy system and present an algorithm to construct it.</jats:p>}},
  author       = {{Kopylov, Denis A. and Meier, Torsten and Sharapova, Polina R.}},
  issn         = {{2521-327X}},
  journal      = {{Quantum}},
  publisher    = {{Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften}},
  title        = {{{Theory of Multimode Squeezed Light Generation in Lossy Media}}},
  doi          = {{10.22331/q-2025-02-04-1621}},
  volume       = {{9}},
  year         = {{2025}},
}

@article{62034,
  abstract     = {{Effective single-particle theories, such as Hartree–Fock, density functional theory, and tight-binding, are limited by the computational cost of the self-consistent field (SCF) procedure, which typically scales cubically with the system size. This makes large-scale applications impractical without specialized algorithms and hardware. Here, we present the submatrix and graphical processing unit (GPU)-accelerated software implementation of the PTB tight-binding potential, realized in the open-source ptb codebase [M. Mueller, A. Katbashev, and S. Ehlert (2025). “grimme-lab/ptb: v3.8.1,” Zenodo. https://zenodo.org/records/17015872]. We first benchmark a traditional diagonalization-based SCF solver against density-matrix-based purification approaches, systematically varying both system size and computer hardware. Our findings show that the usage of GPUs permits shifting the boundaries to much larger systems than previously thought feasible, achieving an overall 10–15-fold performance speedup. Second, we introduce the implementation of a decomposition-type submatrix method, specifically designed for efficient operation on mid- to large-sized systems, to address the computational overhead associated with full-system diagonalization. We demonstrate that, from a certain dimension (≈104 basis functions) on, our submatrix method reduces the overall computational cost while maintaining acceptable numerical accuracy. Our study demonstrates the significance of the interplay between modern hardware, algorithmic considerations, and novel tight-binding methods, paving the way for further development in this direction.}},
  author       = {{Katbashev, Abylay and Schade, Robert and Laß, Michael and Müller, Marcel and Grimme, Stefan and Hansen, Andreas and Kühne, Thomas}},
  issn         = {{0021-9606}},
  journal      = {{The Journal of Chemical Physics}},
  number       = {{13}},
  publisher    = {{AIP Publishing}},
  title        = {{{Submatrix and GPU-accelerated implementation of density matrix tight-binding}}},
  doi          = {{10.1063/5.0271379}},
  volume       = {{163}},
  year         = {{2025}},
}

@article{62064,
  abstract     = {{SYCL is an open standard for targeting heterogeneous hardware from C++. In this work, we evaluate a SYCL implementation for a discontinuous Galerkin discretization of the 2D shallow water equations targeting CPUs, GPUs, and also FPGAs. The discretization uses polynomial orders zero to two on unstructured triangular meshes. Separating memory accesses from the numerical code allow us to optimize data accesses for the target architecture. A performance analysis shows good portability across x86 and ARM CPUs, GPUs from different vendors, and even two variants of Intel Stratix 10 FPGAs. Measuring the energy to solution shows that GPUs yield an up to 10x higher energy efficiency in terms of degrees of freedom per joule compared to CPUs. With custom designed caches, FPGAs offer a meaningful complement to the other architectures with particularly good computational performance on smaller meshes. FPGAs with High Bandwidth Memory are less affected by bandwidth issues and have similar energy efficiency as latest generation CPUs.}},
  author       = {{Büttner, Markus and Alt, Christoph and Kenter, Tobias and Köstler, Harald and Plessl, Christian and Aizinger, Vadym}},
  issn         = {{1573-0484}},
  journal      = {{The Journal of Supercomputing}},
  number       = {{6}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Analyzing performance portability for a SYCL implementation of the 2D shallow water equations}}},
  doi          = {{10.1007/s11227-025-07063-7}},
  volume       = {{81}},
  year         = {{2025}},
}

@inproceedings{62066,
  abstract     = {{In the context of high-performance computing (HPC) for distributed workloads, individual field-programmable gate arrays (FPGAs) need efficient ways to exchange data, which requires network infrastructure and software abstractions. Dedicated multi-FPGA clusters provide inter-FPGA networks for direct device to device communication. The oneAPI high-level synthesis toolchain offers I/O pipes to allow user kernels to interact with the networking ports of the FPGA board. In this work, we evaluate using oneAPI I/O pipes for direct FPGA-to-FPGA communication by scaling a SYCL implementation of a Jacobi solver on up to 25 FPGAs in the Noctua 2 cluster. We see good results in weak and strong scaling experiments.}},
  author       = {{Alt, Christoph and Plessl, Christian and Kenter, Tobias}},
  booktitle    = {{Proceedings of the 13th International Workshop on OpenCL and SYCL}},
  isbn         = {{9798400713606}},
  keywords     = {{Multi-FPGA, High-level Synthesis, oneAPI, FPGA}},
  publisher    = {{Association for Computing Machinery}},
  title        = {{{Evaluating oneAPI I/O Pipes in a Case Study of Scaling a SYCL Jacobi Solver to multiple FPGAs}}},
  doi          = {{10.1145/3731125.3731131}},
  year         = {{2025}},
}

@inproceedings{62065,
  author       = {{Sundriyal, Shivam and Büttner, Markus and Alt, Christoph and Kenter, Tobias and Aizinger, Vadym}},
  booktitle    = {{2025 IEEE High Performance Extreme Computing Conference (HPEC)}},
  publisher    = {{IEEE}},
  title        = {{{Adaptive Spectral Block Floating Point for Discontinuous Galerkin Methods}}},
  doi          = {{10.1109/hpec67600.2025.11196195}},
  year         = {{2025}},
}

@article{62862,
  abstract     = {{<jats:p>Exciton polariton condensates are macroscopic coherent states in which topological excitations can be observed. In this work, we observe the excitation of the vortices and realize tuning the topological charge by manipulating the pumping configurations. Using a digital micromirror device, we constructed an annular pumping pattern where the inner and outer rings can be easily tuned. Both the number and the topological charge of the vortices can be changed by slightly tuning the inner ring position against the outer ring. The experimental results can be reproduced in theory by the Gross–Pitaevskii equation. Our work offers to generate and manipulate vortices in exciton polariton condensates using a straightforward optical method.</jats:p>}},
  author       = {{Ai, Qiang and Ma, Xuekai and Barkhausen, Franziska and Zhai, Xiaokun and Xing, Chunzi and Yang, Xinmiao and Wang, Peilin and Liu, Tianyu and Zhang, Yong and Gu, Yazhou and Li, Peigang and Li, Zhitong and Hatzopoulos, Zacharias and Savvidis, Pavlos G. and Schumacher, Stefan and Gao, Tingge}},
  issn         = {{0003-6951}},
  journal      = {{Applied Physics Letters}},
  number       = {{12}},
  publisher    = {{AIP Publishing}},
  title        = {{{Tuning polariton vortices in an asymmetric ring potential}}},
  doi          = {{10.1063/5.0287076}},
  volume       = {{127}},
  year         = {{2025}},
}

@article{60568,
  author       = {{Bocchini, Adriana and Kollmann, S. and Gerstmann, Uwe and Schmidt, Wolf Gero and Grundmeier, Guido}},
  issn         = {{0039-6028}},
  journal      = {{Surface Science}},
  publisher    = {{Elsevier BV}},
  title        = {{{Phosphonic acid adsorption on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si23.svg" display="inline" id="d1e564"><mml:mi>α</mml:mi></mml:math>-Bi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si24.svg" display="inline" id="d1e569"><mml:msub><mml:mrow/><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si25.svg" display="inline" id="d1e577"><mml:msub><mml:mrow/><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:math> surfaces}}},
  doi          = {{10.1016/j.susc.2025.122776}},
  volume       = {{760}},
  year         = {{2025}},
}

@article{61353,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>Muonic hydrogen is an exotic atom where a muon instead of an electron is bound to a proton. The comparably high mass of the muon (≈ 207 · <jats:italic>m<jats:sub>e</jats:sub>
                  </jats:italic>) has two important effects, (i) the reduced mass of the system becomes more important, and (ii) the muon is localized much closer to the nucleus. Thus, muonic hydrogen is not only excellently suitable for evaluating highly precise quantum electrodynamic (QED) calculations, but may also be used for assessing new approaches including finite nuclear size (FNS) effects to evaluate the proton structure and improve calculation schemes for the hyperfine splittings of many-particle systems, as e.g. to be implemented in density functional theory (DFT) software packages. Here, starting from Dirac’s equation we calculate the relativistic hyperfine splitting of the ground state and several excited states of muonic hydrogen analytically for different charge and magnetization models. The FNS related hyperfine shifts are compared with the differences between QED calculations and experimental measurements. This comparison also allows to unravel the role of the reduced mass, which is on one hand crucial in case of muonic atoms, but on the other hand is by no means well defined in relativistic quantum mechanics.</jats:p>}},
  author       = {{Franzke, Katharina L. and Schmidt, Wolf Gero and Gerstmann, Uwe}},
  issn         = {{1742-6588}},
  journal      = {{Journal of Physics: Conference Series}},
  number       = {{1}},
  publisher    = {{IOP Publishing}},
  title        = {{{Finite-size and relativistic effects onto hyperfine interaction of muonic hydrogen}}},
  doi          = {{10.1088/1742-6596/3027/1/012001}},
  volume       = {{3027}},
  year         = {{2025}},
}

@article{60992,
  abstract     = {{Non-Hermitian systems hosting exceptional points (EPs) exhibit enhanced sensitivity and unconventional mode dynamics. Going beyond isolated EPs, here we report on the existence of exceptional rings (ERs) in planar optical resonators with specific form of circular dichroism and TE-TM splitting. Such exceptional rings possess intriguing topologies as discussed earlier for condensed matter systems, but they remain virtually unexplored in presence of nonlinearity, for which our photonic platform is ideal. We find that when Kerr-type nonlinearity (or saturable gain) is introduced, the linear ER splits into two concentric ERs, with the larger-radius ring being a ring of third-order EPs. Transitioning from linear to nonlinear regime, we present a rigorous analysis of spectral topology and report enhanced and adjustable perturbation response in the nonlinear regime. Whereas certain features are specific to our system, the results on non-Hermitian spectral topology and nonlinearity-enhanced perturbation response are generic and equally relevant to a broad class of other nonlinear non-Hermitian systems, providing a universal framework for engineering ERs and EPs in nonlinear non-Hermitian systems.}},
  author       = {{Wingenbach, Jan and Ares Santos, Laura  and Ma, Xuekai and Sperling, Jan and Schumacher, Stefan}},
  journal      = {{Arxiv}},
  publisher    = {{Arxiv}},
  title        = {{{Sensitivity and Topology of Exceptional Rings in Nonlinear Non-Hermitian Planar Optical Microcavities}}},
  doi          = {{10.48550/ARXIV.2507.07099}},
  year         = {{2025}},
}

@article{62926,
  abstract     = {{<jats:title>Abstract</jats:title>
                  <jats:p>
                    Negatively charged boron vacancies () in hexagonal boron nitride (hBN) are emerging as promising solid‐state spin qubits due to their optical accessibility, structural simplicity, and compatibility with photonic platforms. However, quantifying the density of such defects in thin hBN flakes has remained elusive, limiting progress in device integration and reproducibility. Here, an all‐optical method is presented to quantify  defect density in hBN by correlating Raman and photoluminescence (PL) signatures with irradiation fluence. Two defect‐induced Raman modes, D1 and D2, are identified and assigned them to vibrational modes of  using polarization‐resolved Raman measurements and density functional theory (DFT) calculations. By adapting a numerical model originally developed for graphene, an empirical relationship linking Raman (D1,
                    <jats:italic>E</jats:italic>
                    <jats:sub>2g</jats:sub>
                    ) and PL intensities is established to absolute defect densities. This method is universally applicable across various irradiation types and uniquely suited for thin flakes, where conventional techniques fail. The approach enables accurate, direct, and non‐destructive quantification of spin defect densities down to 10
                    <jats:sup>15</jats:sup>
                     defects/cm
                    <jats:sup>3</jats:sup>
                    , offering a powerful tool for optimizing and benchmarking hBN for quantum optical applications.
                  </jats:p>}},
  author       = {{Patra, Atanu and Konrad, Paul and Sperlich, Andreas and Biktagirov, Timur and Schmidt, Wolf Gero and Spencer, Lesley and Aharonovich, Igor and Höfling, Sven and Dyakonov, Vladimir}},
  issn         = {{1616-301X}},
  journal      = {{Advanced Functional Materials}},
  publisher    = {{Wiley}},
  title        = {{{Quantifying Spin Defect Density in hBN via Raman and Photoluminescence Analysis}}},
  doi          = {{10.1002/adfm.202517851}},
  year         = {{2025}},
}

@article{63160,
  author       = {{Rose, Hendrik and Schumacher, Stefan and Meier, Torsten}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{24}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Microscopic approach to the quantized light-matter interaction in semiconductor nanostructures: Complex coupled dynamics of excitons, biexcitons, and photons}}},
  doi          = {{10.1103/528f-7smh}},
  volume       = {{112}},
  year         = {{2025}},
}

