@article{61110, abstract = {{By analyzing the physics of multi-photon absorption in superconducting nanowire single-photon detectors (SNSPDs), we identify physical components of jitter. From this, we formulate a quantitative physical model of the multi-photon detector response that combines the local detection mechanism and local fluctuations (hotspot formation and intrinsic jitter) with the thermoelectric dynamics of resistive domains. Our model provides an excellent description of the arrival-time histogram of a commercial SNSPD across several orders of magnitude, both in arrival-time probability and across mean photon number. This is achieved with just three fitting parameters: the scaling of the mean arrival time of voltage response pulses, as well as the Gaussian and exponential jitter components. Our findings have important implications for photon-number-resolving detector design, as well as applications requiring low jitter, such as light detection and ranging (LIDAR).}}, author = {{Sidorova, Mariia and Schapeler, Timon and Semenov, Alexej D. and Schlue, Fabian and Stefszky, Michael and Brecht, Benjamin and Silberhorn, Christine and Bartley, Tim}}, issn = {{2378-0967}}, journal = {{APL Photonics}}, keywords = {{Jitter, PNR, SNSPD}}, number = {{8}}, publisher = {{AIP Publishing}}, title = {{{Jitter in photon-number-resolved detection by superconducting nanowires}}}, doi = {{10.1063/5.0273752}}, volume = {{10}}, year = {{2025}}, } @article{60566, author = {{Bocchini, Adriana and Rüsing, Michael and Bollmers, Laura and Lengeling, Sebastian and Mues, Philipp and Padberg, Laura and Gerstmann, Uwe and Silberhorn, Christine and Eigner, Christof and Schmidt, Wolf Gero}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{7}}, publisher = {{American Physical Society (APS)}}, title = {{{Mg dopants in lithium niobate: Defect models and impact on domain inversion}}}, doi = {{10.1103/5wz1-bjyr}}, volume = {{9}}, year = {{2025}}, } @article{63733, abstract = {{We study a possibility of measuring the time-resolved second-order autocorrelation function of one of two beams generated in type-II parametric down-conversion by means of temporal magnification of this beam, bringing its correlation time from the picosecond to the nanosecond scale, which can be resolved by modern photodetectors. We show that such a measurement enables one to infer directly the degree of global coherence of that beam, which is linked by a simple relation to the number of modes characterizing the entanglement between the two generated beams. We illustrate the proposed method by an example of photon pairs generated in a periodically poled potassium titanyl phosphate (KTP) crystal with a symmetric group velocity matching for various durations of the pump pulse, resulting in different numbers of modes. Our theoretical model also shows that the magnified double-heralded autocorrelation function of one beam exhibits a local maximum around zero delay time, corresponding to photon bunching at a short time scale.}}, author = {{Horoshko, Dmitri B. and Srivastava, Shivang and Sośnicki, Filip Maksymilian and Mikołajczyk, Michał and Karpiński, Michał and Brecht, Benjamin and Kolobov, Mikhail I.}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Time-resolved second-order autocorrelation function of parametric down-conversion}}}, doi = {{10.1103/7ckm-tm3r}}, volume = {{112}}, year = {{2025}}, } @article{58606, author = {{Mathew, Albert and Aschwanden, Rebecca and Tripathi, Aditya and Jangid, Piyush and Sain, Basudeb and Zentgraf, Thomas and Kruk, Sergey}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{metasurfaces, nanophotonics, nonreciprocity, optical isolators, silicon photonics}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Nonreciprocal Metasurfaces with Epsilon-Near-Zero Materials}}}, doi = {{10.1021/acs.nanolett.4c06188}}, year = {{2025}}, } @misc{63855, abstract = {{Elektronenenergieverlustspektroskopie (engl. EELS) ist eine fortgeschrittene Analysemethode der Transmissionselektronenmikroskopie, die auf atomarer Ebene Einblicke in Materialcharakteristika wie bspw. Eigenschaften des Elektronensystems oder der Materialzusammensetzung erlaubt. Die Genauigkeit jeder EELS-Analyse ist jedoch fundamental durch Rauschen und Unschärfe begrenzt. Diese Thesis beschreibt solche Rauschphänomene im Detail. Vor allem bei strahlempfindlichen Materialien, die kurze Bestrahlzeiten erfordern, aber auch bei Elektron-Materie-Wechselwirkungen mit geringer Auftrittshäufigkeit, ist eine solche Beschreibung notwendig, da das Rauschen solche Messungen dominiert. Zusätzlich spielen Korrelationen des Rauschens eine Rolle, die durch Faltung des verrauschten Signals mit der Punktspreizfunktion des Detektors entstehen und die sowohl theoretisch als auch experimentell beschrieben werden. Methoden zur Messung der wichtigsten Rauschparameter bei typischen Detektorsystemen werden vorgestellt und erlauben es, das Rauschmodel auf jeden beliebigen EELS-Detektor anzupassen. Eine neue Entfaltungsmethode wird vorgeschlagen, die EELS-Messungen schärft und entrauscht. Die Wirksamkeit dieser Methode wird an Simulations- und Experimentaldaten dargelegt. Hierbei wird gezeigt, dass die neue Methode signifikant bessere Ergebnisse liefert, als bisherige und somit eine Analyse von Messdaten auf einem Level ermöglicht, das die Möglichkeiten der Elektronenmikroskopie deutlich erweitert.}}, author = {{Zietlow, Christian}}, publisher = {{Universitätsbibliothek Paderborn}}, title = {{{A novel Lagrangian-based method for the deconvolution of electron energy-loss spectra}}}, doi = {{10.17619/UNIPB/1-2438}}, year = {{2025}}, } @article{65611, abstract = {{ Spins confined in optically active quantum dot molecules (QDMs) can be used for the deterministic generation of photonic graph states with tailored entanglement structures. Their usefulness for the generation of such nonclassical states of light is determined by orbital and spin decoherence mechanisms, particularly phonon-mediated processes dominant at energy scales up to a few millielectronvolts. Here, we directly measure the spectral function of orbital phonon relaxation between the energy states of the neutral exciton in a QDM and benchmark our findings against microscopic k · p theory. Our results reveal pronounced resonances and antiresonances in the phonon-relaxation rates, ranging from tens of µ s − 1 up to tens of ns − 1 . Comparison with a kinetic model reveals the voltage (energy) dependent phonon coupling strength and fully explains the interplay between phonon-assisted relaxation and radiative recombination. The resonances and antiresonances enable further tunability of the exciton lifetime which can be leveraged to increase the lifetime of energetically unfavorable charge configurations needed for realizing efficient spin-photon interfaces and multidimensional cluster states. }}, author = {{Lienhart, Michelle and Gawarecki, Krzysztof and Stöcker, Markus and Bopp, Frederik and Cullip, Charlotte and Akhlaq, Nadeem and Thalacker, Christopher and Schall, Johannes and Rodt, Sven and Ludwig, Arne and Reuter, Dirk and Reitzenstein, Stephan and Müller, Kai and Machnikowski, Paweł and Finley, Jonathan J.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{23}}, publisher = {{American Physical Society (APS)}}, title = {{{Resonant and antiresonant exciton-phonon coupling in quantum dot molecules}}}, doi = {{10.1103/xc25-1tph}}, volume = {{112}}, year = {{2025}}, } @article{65669, abstract = {{Local droplet etching and subsequent refilling enables the fabrication of highly symmetric quantum dots with low fine structure splitting, suitable for generating polarization entangled photons. While well established in GaAs/AlxGa1−xAs, this approach does not yield emission in the telecom bands required for low loss fiber-based quantum communication. To achieve emission at 1.55 μm, local droplet etching must be adapted to alternative material platforms such as InP. Here, we systematically investigate how the etching material deposition rate and etching time influence nanohole morphology in In0.52Al0.48As layers lattice-matched to InP. In the first experiment, InAl was deposited at fluxes of 0.2–4.0 Å s−1 at Tetch = 350 °C and 460 °C. Lower fluxes produced nanoholes with lower density and larger ring diameters, indicating fewer and larger initial droplets, consistent with scaling theory. The average nanohole diameter decreased monotonically with increasing flux, whereas the average depth showed no clear dependence on flux. In the second experiment, etching times of 30–600 s were tested for InAl, In, and Al droplets. Average nanohole diameters remained constant for Al across all etching times, but decreased for In and InAl with increasing etching time, suggesting sidewall redeposition during etching. For all droplet types, depths peaked at intermediate times and decreased for prolonged etching, consistent with material diffusion into the nanohole after droplet consumption.}}, author = {{Deutsch, Dennis and Reuter, Dirk}}, issn = {{2073-4352}}, journal = {{Crystals}}, number = {{11}}, publisher = {{MDPI AG}}, title = {{{Influence of the Etching Material Deposition Rate and Annealing Time on Nanohole Morphology Etched into InP/In0.52Al0.48As Layers via Local Droplet Epitaxy}}}, doi = {{10.3390/cryst15110913}}, volume = {{15}}, year = {{2025}}, } @article{50829, author = {{Heinisch, Nils and Köcher, Nikolas and Bauch, David and Schumacher, Stefan}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Swing-up dynamics in quantum emitter cavity systems: Near ideal single photons and entangled photon pairs}}}, doi = {{10.1103/PhysRevResearch.6.L012017}}, volume = {{6}}, year = {{2024}}, } @article{51105, author = {{Wingenbach, Jan and Schumacher, Stefan and Ma, Xuekai}}, journal = {{Physical Review Research, in press}}, title = {{{Manipulating spectral topology and exceptional points by nonlinearity in non-Hermitian polariton systems}}}, year = {{2024}}, } @article{51104, author = {{Liang, Qian and Ma, Xuekai and Gu, Chunling and Ren, Jiahuan and An, Cunbin and Fu, Hongbing and Schumacher, Stefan and Liao, Qing}}, journal = {{Journal of the American Chemical Society (JACS)}}, title = {{{Photochemical Reaction Enabling the Engineering of Photonic Spin−Orbit Coupling in Organic-Crystal Optical Microcavities}}}, doi = {{10.1021/jacs.3c11373}}, year = {{2024}}, } @article{51156, abstract = {{Ferroelectric domain wall (DW) conductivity (DWC) can be attributed to two separate mechanisms: (a) the injection/ejection of charge carriers across the Schottky barrier formed at the (metal-)electrode-DW junction and (b) the transport of those charge carriers along the DW. Current-voltage (I-U) characteristics, recorded at variable temperatures from LiNbO3 (LNO) DWs, are clearly able to differentiate between these two contributions. Practically, they allow us to directly quantify the physical parameters relevant to the two mechanisms (a) and (b) mentioned above. These are, for example, the resistance of the DW, the saturation current, the ideality factor, and the Schottky barrier height of the electrode-DW junction. Furthermore, the activation energies needed to initiate the thermally activated electronic transport along the DWs can be extracted. In addition, we show that electronic transport along LNO DWs can be elegantly viewed and interpreted in an adapted semiconductor picture based on a double-diode, double-resistor equivalent-circuit model, the R2D2 model. Finally, our R2D2 model was checked for its universality by successfully fitting the I-U curves of not only z-cut LNO bulk DWs, but equally of z-cut thin-film LNO DWs, and of x-cut thin-film DWs as reported in literature.}}, author = {{Zahn, Manuel and Beyreuther, Elke and Kiseleva, Iuliia and Lotfy, Ahmed Samir and McCluskey, Conor J. and Maguire, Jesi R. and Suna, Ahmet and Rüsing, Michael and Gregg, J. Marty and Eng, Lukas M.}}, issn = {{2331-7019}}, journal = {{Physical Review Applied}}, keywords = {{General Physics and Astronomy}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Equivalent-circuit model that quantitatively describes domain-wall conductivity in ferroelectric lithium }}}, doi = {{10.1103/physrevapplied.21.024007}}, volume = {{21}}, year = {{2024}}, } @article{51221, abstract = {{Charge transfer mechanism in the deprotonation-induced n-type doping of PCBM.}}, author = {{Dong, Chuan-Ding and Bauch, Fabian and Hu, Yuanyuan and Schumacher, Stefan}}, issn = {{1463-9076}}, journal = {{Physical Chemistry Chemical Physics}}, keywords = {{Physical and Theoretical Chemistry, General Physics and Astronomy}}, number = {{5}}, pages = {{4194--4199}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Charge transfer in superbase n-type doping of PCBM induced by deprotonation}}}, doi = {{10.1039/d3cp05105f}}, volume = {{26}}, year = {{2024}}, } @article{51339, author = {{Babai-Hemati, Jonas and vom Bruch, Felix and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, publisher = {{Optica Publishing Group}}, title = {{{Tailored second harmonic generation inTi-diffused PPLN waveguides usingmicro-heaters}}}, doi = {{10.1364/oe.510319}}, year = {{2024}}, } @article{51519, author = {{Cui, Tie Jun and Zhang, Shuang and Alu, Andrea and Wegener, Martin and Pendry, John and Luo, Jie and Lai, Yun and Wang, Zuojia and Lin, Xiao and Chen, Hongsheng and Chen, Ping and Wu, Rui-Xin and Yin, Yuhang and Zhao, Pengfei and Chen, Huanyang and Li, Yue and Zhou, Ziheng and Engheta, Nader and Asadchy, V. S. and Simovski, Constantin and Tretyakov, Sergei A and Yang, Biao and Campbell, Sawyer D. and Hao, Yang and Werner, Douglas H and Sun, Shulin and Zhou, Lei and Xu, Su and Sun, Hong-Bo and Zhou, Zhou and Li, Zile and Zheng, Guoxing and Chen, Xianzhong and Li, Tao and Zhu, Shi-Ning and Zhou, Junxiao and Zhao, Junxiang and Liu, Zhaowei and Zhang, Yuchao and Zhang, Qiming and Gu, Min and Xiao, Shumin and Liu, Yongmin and Zhang, Xiaoyu and Tang, Yutao and Li, Guixin and Zentgraf, Thomas and Koshelev, Kirill and Kivshar, Yuri S. and Li, Xin and Badloe, Trevon and Huang, Lingling and Rho, Junsuk and Wang, Shuming and Tsai, Din Ping and Bykov, A. Yu. and Krasavin, Alexey V and Zayats, Anatoly V and McDonnell, Cormac and Ellenbogen, Tal and Luo, Xiangang and Pu, Mingbo and Garcia-Vidal, Francisco J and Liu, Liangliang and Li, Zhuo and Tang, Wenxuan and Ma, Hui Feng and Zhang, Jingjing and Luo, Yu and Zhang, Xuanru and Zhang, Hao Chi and He, Pei Hang and Zhang, Le Peng and Wan, Xiang and Wu, Haotian and Liu, Shuo and Jiang, Wei Xiang and Zhang, Xin Ge and Qiu, Chengwei and Ma, Qian and Liu, Che and Li, Long and Han, Jiaqi and Li, Lianlin and Cotrufo, Michele and Caloz, Christophe and Deck-Léger, Z.-L. and Bahrami, A. and Céspedes, O. and Galiffi, Emanuele and Huidobro, P. A. and Cheng, Qiang and Dai, Jun Yan and Ke, Jun Cheng and Zhang, Lei and Galdi, Vincenzo and Di Renzo, Marco}}, issn = {{2515-7647}}, journal = {{Journal of Physics: Photonics}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, publisher = {{IOP Publishing}}, title = {{{Roadmap on electromagnetic metamaterials and metasurfaces}}}, doi = {{10.1088/2515-7647/ad1a3b}}, year = {{2024}}, } @article{52534, author = {{Bauch, Fabian and Dong, Chuan-Ding and Schumacher, Stefan}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, keywords = {{Surfaces, Coatings and Films, Physical and Theoretical Chemistry, General Energy, Electronic, Optical and Magnetic Materials}}, number = {{8}}, pages = {{3525--3532}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Dynamics of Electron–Hole Coulomb Attractive Energy and Dipole Moment of Hot Excitons in Donor–Acceptor Polymers}}}, doi = {{10.1021/acs.jpcc.3c07513}}, volume = {{128}}, year = {{2024}}, } @article{52723, abstract = {{Miller's rule is an empirical relation between the nonlinear and linear optical coefficients that applies to a large class of materials but has only been rigorously derived for the classical Lorentz model with a weak anharmonic perturbation. In this work, we extend the proof and present a detailed derivation of Miller's rule for an equivalent quantum-mechanical anharmonic oscillator. For this purpose, the classical concept of velocity-dependent damping inherent to the Lorentz model is replaced by an adiabatic switch-on of the external electric field, which allows a unified treatment of the classical and quantum-mechanical systems using identical potentials and fields. Although the dynamics of the resulting charge oscillations, and hence the induced polarizations, deviate due to the finite zero-point motion in the quantum-mechanical framework, we find that Miller's rule is nevertheless identical in both cases up to terms of first order in the anharmonicity. With a view to practical applications, especially in the context of ab initio calculations for the optical response where adiabatically switched-on fields are widely assumed, we demonstrate that a correct treatment of finite broadening parameters is essential to avoid spurious errors that may falsely suggest a violation of Miller's rule, and we illustrate this point by means of a numerical example.}}, author = {{Meyer, Maximilian Tim and Schindlmayr, Arno}}, issn = {{1361-6455}}, journal = {{Journal of Physics B: Atomic, Molecular and Optical Physics}}, number = {{9}}, publisher = {{IOP Publishing}}, title = {{{Derivation of Miller's rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator}}}, doi = {{10.1088/1361-6455/ad369c}}, volume = {{57}}, year = {{2024}}, } @article{35665, author = {{Wolke, Nathalie and Laumann, Daniel and Webersen, Yvonne}}, journal = {{Physics Education}}, title = {{{Interdisciplinary approaches between physics and art using the example of optical experiments and artistic light installations}}}, doi = {{10.1088/1361-6552/ad40ee}}, year = {{2024}}, } @article{54093, author = {{Pinske, Julien and Sperling, Jan}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{5}}, publisher = {{American Physical Society (APS)}}, title = {{{Unbreakable and breakable quantum censorship}}}, doi = {{10.1103/physreva.109.052408}}, volume = {{109}}, year = {{2024}}, } @article{54544, abstract = {{The biphoton correlation time, a measure for the conditional uncertainty in the temporal arrival of two photons from a photon pair source, is a key performance identifier for many quantum spectroscopy applications, with shorter correlation times typically yielding better performance. Furthermore, it provides fundamental insight into the effects of dispersion on the biphoton state. Here, we show that a characteristic dependence of the width of the temporal interferogram can be exploited to obtain insights into the amount of second-order dispersion inside the interferometer and to retrieve actual and Fourier-limited ultrashort biphoton correlation times of around 100 fs. In the presented scheme, we simultaneously measure spectral and temporal interferograms at the output of an SU(1,1) interferometer based on an integrated broadband parametric down conversion source in a Ti:LiNbO3 waveguide.}}, author = {{Roeder, Franz and Pollmann, René and Stefszky, Michael and Santandrea, Matteo and Luo, Kai Hong and Quiring, V. and Ricken, Raimund and Eigner, Christof and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{2691-3399}}, journal = {{PRX Quantum}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Measurement of Ultrashort Biphoton Correlation Times with an Integrated Two-Color Broadband SU(1,1)-Interferometer}}}, doi = {{10.1103/prxquantum.5.020350}}, volume = {{5}}, year = {{2024}}, } @article{54812, author = {{Weinbrenner, Lisa T. and Prasannan, Nidhin and Hansenne, Kiara and Denker, Sophia and Sperling, Jan and Brecht, Benjamin and Silberhorn, Christine and Gühne, Otfried}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, number = {{24}}, publisher = {{American Physical Society (APS)}}, title = {{{Certifying the Topology of Quantum Networks: Theory and Experiment}}}, doi = {{10.1103/physrevlett.132.240802}}, volume = {{132}}, year = {{2024}}, }