@article{46480, author = {{Müller, Hendrik and Weinberger, Christian and Grundmeier, Guido and de los Arcos de Pedro, Maria Teresa}}, issn = {{0368-2048}}, journal = {{Journal of Electron Spectroscopy and Related Phenomena}}, keywords = {{Physical and Theoretical Chemistry, Spectroscopy, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Radiation, Electronic, Optical and Magnetic Materials}}, publisher = {{Elsevier BV}}, title = {{{UV-enhanced environmental charge compensation in near ambient pressure XPS}}}, doi = {{10.1016/j.elspec.2023.147317}}, volume = {{264}}, year = {{2023}}, } @article{46644, abstract = {{A reliable, but cost-effective generation of single-photon states is key for practical quantum communication systems. For real-world deployment, waveguide sources offer optimum compatibility with fiber networks and can be embedded in hybrid integrated modules. Here, we present what we believe to be the first chip-size fully integrated fiber-coupled heralded single photon source (HSPS) module based on a hybrid integration of a nonlinear lithium niobate waveguide into a polymer board. Photon pairs at 810 nm (signal) and 1550 nm (idler) are generated via parametric down-conversion pumped at 532 nm in the LiNbO3 waveguide. The pairs are split in the polymer board and routed to separate output ports. The module has a size of (2 × 1) cm^2 and is fully fiber-coupled with one pump input fiber and two output fibers. We measure a heralded second-order correlation function of g_h(2)=0.05 with a heralding efficiency of η_h=3.5% at low pump powers}}, author = {{Kießler, Christian and Conradi, Hauke and Kleinert, Moritz and Quiring, Viktor and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{14}}, publisher = {{Optica Publishing Group}}, title = {{{Fiber-coupled plug-and-play heralded single photon source based on Ti:LiNbO3 and polymer technology}}}, doi = {{10.1364/oe.487581}}, volume = {{31}}, year = {{2023}}, } @inproceedings{46813, abstract = {{Modelling of dynamic systems plays an important role in many engineering disciplines. Two different approaches are physical modelling and data‐driven modelling, both of which have their respective advantages and disadvantages. By combining these two approaches, hybrid models can be created in which the respective disadvantages are mitigated, with discrepancy models being a particular subclass. Here, the basic system behaviour is described physically, that is, in the form of differential equations. Inaccuracies resulting from insufficient modelling or numerics lead to a discrepancy between the measurements and the model, which can be compensated by a data‐driven error correction term. Since discrepancy methods still require a large amount of measurement data, this paper investigates the extent to which a single discrepancy model can be trained for a physical model with additional parameter dependencies without the need for retraining. As an example, a damped electromagnetic oscillating circuit is used. The physical model is realised by a differential equation describing the electric current, considering only inductance and capacitance; dissipation due to resistance is neglected. This creates a discrepancy between measurement and model, which is corrected by a data‐driven model. In the experiments, the inductance and the capacity are varied. It is found that the same data‐driven model can only be used if additional parametric dependencies in the data‐driven term are considered as well.}}, author = {{Wohlleben, Meike Claudia and Muth, Lars and Peitz, Sebastian and Sextro, Walter}}, booktitle = {{Proceedings in Applied Mathematics and Mechanics}}, issn = {{1617-7061}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics}}, publisher = {{Wiley}}, title = {{{Transferability of a discrepancy model for the dynamics of electromagnetic oscillating circuits}}}, doi = {{10.1002/pamm.202300039}}, year = {{2023}}, } @article{36471, abstract = {{Superconducting nanowire single-photon detectors (SNSPDs) show near unity efficiency, low dark count rate, and short recovery time. Combining these characteristics with temporal control of SNSPDs broadens their applications as in active de-latching for higher dynamic range counting or temporal filtering for pump-probe spectroscopy or LiDAR. To that end, we demonstrate active gating of an SNSPD with a minimum off-to-on rise time of 2.4 ns and a total gate length of 5.0 ns. We show how the rise time depends on the inductance of the detector in combination with the control electronics. The gate window is demonstrated to be fully and freely, electrically tunable up to 500 ns at a repetition rate of 1.0 MHz, as well as ungated, free-running operation. Control electronics to generate the gating are mounted on the 2.3 K stage of a closed-cycle sorption cryostat, while the detector is operated on the cold stage at 0.8 K. We show that the efficiency and timing jitter of the detector is not altered during the on-time of the gating window. We exploit gated operation to demonstrate a method to increase in the photon counting dynamic range by a factor 11.2, as well as temporal filtering of a strong pump in an emulated pump-probe experiment.}}, author = {{Hummel, Thomas and Widhalm, Alex and Höpker, Jan Philipp and Jöns, Klaus and Chang, Jin and Fognini, Andreas and Steinhauer, Stephan and Zwiller, Val and Zrenner, Artur and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{Optica Publishing Group}}, title = {{{Nanosecond gating of superconducting nanowire single-photon detectors using cryogenic bias circuitry}}}, doi = {{10.1364/oe.472058}}, volume = {{31}}, year = {{2023}}, } @article{41035, author = {{Sharapova, Polina R. and Kruk, Sergey S. and Solntsev, Alexander S.}}, issn = {{1863-8880}}, journal = {{Laser & Photonics Reviews}}, keywords = {{Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, publisher = {{Wiley}}, title = {{{Nonlinear Dielectric Nanoresonators and Metasurfaces: Toward Efficient Generation of Entangled Photons}}}, doi = {{10.1002/lpor.202200408}}, year = {{2023}}, } @article{45859, abstract = {{Sport-related concussions (SRC) are characterized by impaired autonomic control. Heart rate variability (HRV) offers easily obtainable diagnostic approaches to SRC-associated dysautonomia, but studies investigating HRV during sleep, a crucial time for post-traumatic cerebral regeneration, are relatively sparse. The aim of this study was to assess nocturnal HRV in athletes during their return to sports (RTS) after SRC in their home environment using wireless wrist sensors (E4, Empatica, Milan, Italy) and to explore possible relations with clinical concussion-associated sleep symptoms. Eighteen SRC athletes wore a wrist sensor obtaining photoplethysmographic data at night during RTS as well as one night after full clinical recovery post RTS (>3 weeks). Nocturnal heart rate and parasympathetic activity of HRV (RMSSD) were calculated and compared using the Mann–Whitney U Test to values of eighteen; matched by sex, age, sport, and expertise, control athletes underwent the identical protocol. During RTS, nocturnal RMSSD of SRC athletes (Mdn = 77.74 ms) showed a trend compared to controls (Mdn = 95.68 ms, p = 0.021, r = −0.382, p adjusted using false discovery rate = 0.126) and positively correlated to “drowsiness” (r = 0.523, p = 0.023, p adjusted = 0.046). Post RTS, no differences in RMSSD between groups were detected. The presented findings in nocturnal cardiac parasympathetic activity during nights of RTS in SRC athletes might be a result of concussion, although its relation to recovery still needs to be elucidated. Utilization of wireless sensors and wearable technologies in home-based settings offer a possibility to obtain helpful objective data in the management of SRC.}}, author = {{Delling, Anne Carina and Jakobsmeyer, Rasmus and Coenen, Jessica and Christiansen, Nele and Reinsberger, Claus}}, issn = {{1424-8220}}, journal = {{Sensors}}, keywords = {{Electrical and Electronic Engineering, Biochemistry, Instrumentation, Atomic and Molecular Physics, and Optics, Analytical Chemistry}}, number = {{9}}, publisher = {{MDPI AG}}, title = {{{Home-Based Measurements of Nocturnal Cardiac Parasympathetic Activity in Athletes during Return to Sport after Sport-Related Concussion}}}, doi = {{10.3390/s23094190}}, volume = {{23}}, year = {{2023}}, } @article{29716, author = {{Widhalm, Alex and Golla, Christian and Weber, Nils and Mackwitz, Peter and Zrenner, Artur and Meier, Cedrik}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{The Optical Society}}, title = {{{Electric-field-induced second harmonic generation in silicon dioxide}}}, doi = {{10.1364/oe.443489}}, volume = {{30}}, year = {{2022}}, } @article{30195, abstract = {{While plasmonic particles can provide optical resonances in a wide spectral range from the lower visible up to the near-infrared, often, symmetry effects are utilized to obtain particular optical responses. By breaking certain spatial symmetries, chiral structures arise and provide robust chiroptical responses to these plasmonic resonances. Here, we observe strong chiroptical responses in the linear and nonlinear optical regime for chiral L-handed helicoid-III nanoparticles and quantify them by means of an asymmetric factor, the so-called g-factor. We calculate the linear optical g-factors for two distinct chiroptical resonances to −0.12 and –0.43 and the nonlinear optical g-factors to −1.45 and −1.63. The results demonstrate that the chirality of the helicoid-III nanoparticles is strongly enhanced in the nonlinear regime.}}, author = {{Spreyer, Florian and Mun, Jungho and Kim, Hyeohn and Kim, Ryeong Myeong and Nam, Ki Tae and Rho, Junsuk and Zentgraf, Thomas}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Biotechnology, Electronic, Optical and Magnetic Materials}}, number = {{3}}, pages = {{784–792}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Second Harmonic Optical Circular Dichroism of Plasmonic Chiral Helicoid-III Nanoparticles}}}, doi = {{10.1021/acsphotonics.1c00882}}, volume = {{9}}, year = {{2022}}, } @article{30342, author = {{Lange, Nina Amelie and Höpker, Jan Philipp and Ricken, Raimund and Quiring, Viktor and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{2334-2536}}, journal = {{Optica}}, keywords = {{Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, number = {{1}}, publisher = {{The Optical Society}}, title = {{{Cryogenic integrated spontaneous parametric down-conversion}}}, doi = {{10.1364/optica.445576}}, volume = {{9}}, year = {{2022}}, } @article{33672, abstract = {{Abstract Lithium niobate is a promising platform for integrated quantum optics. In this platform, we aim to efficiently manipulate and detect quantum states by combining superconducting single photon detectors and modulators. The cryogenic operation of a superconducting single photon detector dictates the optimisation of the electro-optic modulators under the same operating conditions. To that end, we characterise a phase modulator, directional coupler, and polarisation converter at both ambient and cryogenic temperatures. The operation voltage V π / 2 of these modulators increases, due to the decrease in the electro-optic effect, by 74% for the phase modulator, 84% for the directional coupler and 35% for the polarisation converter below 8.5 K . The phase modulator preserves its broadband nature and modulates light in the characterised wavelength range. The unbiased bar state of the directional coupler changed by a wavelength shift of 85 n m while cooling the device down to 5 K . The polarisation converter uses periodic poling to phasematch the two orthogonal polarisations. The phasematched wavelength of the utilised poling changes by 112 n m when cooling to 5 K .}}, author = {{Thiele, Frederik and vom Bruch, Felix and Brockmeier, Julian and Protte, Maximilian and Hummel, Thomas and Ricken, Raimund and Quiring, Viktor and Lengeling, Sebastian and Herrmann, Harald and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{2515-7647}}, journal = {{Journal of Physics: Photonics}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, number = {{3}}, publisher = {{IOP Publishing}}, title = {{{Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides}}}, doi = {{10.1088/2515-7647/ac6c63}}, volume = {{4}}, year = {{2022}}, } @article{33673, abstract = {{ Superconducting Nanowire Single Photon Detectors (SNSPDs) have become an integral part of quantum optics in recent years because of their high performance in single photon detection. We present a method to replace the electrical input by supplying the required bias current via the photocurrent of a photodiode situated on the cold stage of the cryostat. Light is guided to the bias photodiode through an optical fiber, which enables a lower thermal conduction and galvanic isolation between room temperature and the cold stage. We show that an off-the-shelf InGaAs–InP photodiode exhibits a responsivity of at least 0.55 A/W at 0.8 K. Using this device to bias an SNSPD, we characterize the count rate dependent on the optical power incident on the photodiode. This configuration of the SNSPD and photodiode shows an expected plateau in the single photon count rate with an optical bias power on the photodiode above 6.8 µW. Furthermore, we compare the same detector under both optical and electrical bias, and show there is no significant changes in performance. This has the advantage of avoiding an electrical input cable, which reduces the latent heat load by a factor of 100 and, in principle, allows for low loss RF current supply at the cold stage. }}, author = {{Thiele, Frederik and Hummel, Thomas and Protte, Maximilian and Bartley, Tim}}, issn = {{2378-0967}}, journal = {{APL Photonics}}, keywords = {{Computer Networks and Communications, Atomic and Molecular Physics, and Optics}}, number = {{8}}, publisher = {{AIP Publishing}}, title = {{{Opto-electronic bias of a superconducting nanowire single photon detector using a cryogenic photodiode}}}, doi = {{10.1063/5.0097506}}, volume = {{7}}, year = {{2022}}, } @article{47980, abstract = {{Recently, ferroelectric domain walls (DWs) have attracted considerable attention due to their intrinsic topological effects and their huge potential for optoelectronic applications. In contrast, many of the underlying physical properties and phenomena are not well characterized. In this regard, analyzing the vibrational properties, e.g. by Raman spectroscopy, provides direct access to the various local material properties, such as strains, defects or electric fields. While the optical phonon spectra of DWs have been widely investigated in the past, no reports on the acoustic phonon properties of DWs exist. In this work, we present a joint Raman and Brillouin visualization of ferroelectric DWs in the model ferroelectric lithium niobate. This is possible by using a combined Raman and virtually imaged phased array Brillouin setup. Here, we show that DWs can be visualized via frequency shifts observed in the acoustic phonons, as well. The observed contrast then is qualitatively explained by models adapted from Raman spectroscopy. This work, hence, provides a novel route to study ferroelectric DWs and their intrinsic mechanical properties.}}, author = {{Rix, Jan and Rüsing, Michael and Galli, Roberta and Golde, Jonas and Reitzig, Sven and Eng, Lukas M. and Koch, Edmund}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{Optica Publishing Group}}, title = {{{Brillouin and Raman imaging of domain walls in periodically-poled 5%-MgO:LiNbO3}}}, doi = {{10.1364/oe.447554}}, volume = {{30}}, year = {{2022}}, } @article{30678, author = {{Javed, Muhammad Ali and Vater, Sebastian and Baumhögger, Elmar and Windmann, Thorsten and Vrabec, Jadran}}, issn = {{0021-9614}}, journal = {{The Journal of Chemical Thermodynamics}}, keywords = {{Physical and Theoretical Chemistry, General Materials Science, Atomic and Molecular Physics, and Optics}}, publisher = {{Elsevier BV}}, title = {{{Apparatus for the measurement of the thermodynamic speed of sound of diethylene glycol and triethylene glycol}}}, doi = {{10.1016/j.jct.2022.106766}}, year = {{2022}}, } @article{33255, author = {{Betken, Benjamin and Beckmüller, Robin and Ali Javed, Muhammad and Baumhögger, Elmar and Span, Roland and Vrabec, Jadran and Thol, Monika}}, issn = {{0021-9614}}, journal = {{The Journal of Chemical Thermodynamics}}, keywords = {{Physical and Theoretical Chemistry, General Materials Science, Atomic and Molecular Physics, and Optics}}, publisher = {{Elsevier BV}}, title = {{{Thermodynamic Properties for 1-Hexene – Measurements and Modeling}}}, doi = {{10.1016/j.jct.2022.106881}}, year = {{2022}}, } @article{32088, abstract = {{Subwavelength dielectric resonators assembled into metasurfaces have become a versatile tool for miniaturizing optical components approaching the nanoscale. An important class of metasurface functionalities is associated with asymmetry in both the generation and transmission of light with respect to reversals of the positions of emitters and receivers. The nonlinear light–matter interaction in metasurfaces offers a promising pathway towards miniaturization of the asymmetric control of light. Here we demonstrate asymmetric parametric generation of light in nonlinear metasurfaces. We assemble dissimilar nonlinear dielectric resonators into translucent metasurfaces that produce images in the visible spectral range on being illuminated by infrared radiation. By design, the metasurfaces produce different and completely independent images for the reversed direction of illumination, that is, when the positions of the infrared emitter and the visible light receiver are exchanged. Nonlinearity-enabled asymmetric control of light by subwavelength resonators paves the way towards novel nanophotonic components via dense integration of large quantities of nonlinear resonators into compact metasurface designs.}}, author = {{Kruk, Sergey S. and Wang, Lei and Sain, Basudeb and Dong, Zhaogang and Yang, Joel and Zentgraf, Thomas and Kivshar, Yuri}}, issn = {{1749-4885}}, journal = {{Nature Photonics}}, keywords = {{Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, pages = {{561–565}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Asymmetric parametric generation of images with nonlinear dielectric metasurfaces}}}, doi = {{10.1038/s41566-022-01018-7}}, volume = {{16}}, year = {{2022}}, } @article{32148, author = {{Gao, Xinghui and Hu, Wei and Schumacher, Stefan and Ma, Xuekai}}, issn = {{0146-9592}}, journal = {{Optics Letters}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{13}}, pages = {{3235--3238}}, publisher = {{Optica Publishing Group}}, title = {{{Unidirectional vortex waveguides and multistable vortex pairs in polariton condensates}}}, doi = {{10.1364/ol.457724}}, volume = {{47}}, year = {{2022}}, } @article{33587, abstract = {{Abstract We performed a virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated usingthe hybrid density functional theory including exact Hartree–Fock exchange. Our final list contains materials which have band gaps between 1.0 and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes.}}, author = {{Ranjbar, Ahmad and Mirhosseini, Hossein and Kühne, Thomas D}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, keywords = {{Condensed Matter Physics, General Materials Science, Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{On topological materials as photocatalysts for water splitting by visible light}}}, doi = {{10.1088/2515-7639/ac363d}}, volume = {{5}}, year = {{2021}}, } @article{33659, abstract = {{Abstract We performed a virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated usingthe hybrid density functional theory including exact Hartree–Fock exchange. Our final list contains materials which have band gaps between 1.0 and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes.}}, author = {{Ranjbar, Ahmad and Mirhosseini, Hossein and Kühne, Thomas}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, keywords = {{Condensed Matter Physics, General Materials Science, Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{On topological materials as photocatalysts for water splitting by visible light}}}, doi = {{10.1088/2515-7639/ac363d}}, volume = {{5}}, year = {{2021}}, } @article{47974, abstract = {{Domain walls (DWs) in ferroelectric (FE) and multiferroic materials possess an ever-growing potential as integrated functional elements, for instance in optoelectronic nanodevices. Mandatory, however, is the profound knowledge of the local-scale electronic and optical properties, especially at DWs that are still incompletely characterized to date. Here, we quantify the refractive index of individual FE DWs in periodically-poled LiNbO3 (PPLN) single crystals. When applying polarization-sensitive optical coherence tomography (PS-OCT) at 1300 nm using circular light polarization, we are able to probe the relevant electro-optical properties close to and at the DWs, including also their ordinary and extraordinary contributions. When comparing to numerical calculations, we conclude that the DW signals recorded for ordinary and extraordinary polarization stem from an increased refractive index of at least Δn > 2·10−3 that originates from a tiny region of < 30 nm in width. PS-OCT hence provides an extremely valuable tool to decipher and quantify subtle changes of refractive index profiles for both inorganic and biomedical nanomaterial systems.}}, author = {{Golde, Jonas and Rüsing, Michael and Rix, Jan and Eng, Lukas M. and Koch, Edmund}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{21}}, publisher = {{Optica Publishing Group}}, title = {{{Quantifying the refractive index of ferroelectric domain walls in periodically poled LiNbO3 single crystals by polarization-sensitive optical coherence tomography}}}, doi = {{10.1364/oe.432810}}, volume = {{29}}, year = {{2021}}, } @article{29780, abstract = {{A central tenet of theoretical cryptography is the study of the minimal assumptions required to implement a given cryptographic primitive. One such primitive is the one-time memory (OTM), introduced by Goldwasser, Kalai, and Rothblum [CRYPTO 2008], which is a classical functionality modeled after a non-interactive 1-out-of-2 oblivious transfer, and which is complete for one-time classical and quantum programs. It is known that secure OTMs do not exist in the standard model in both the classical and quantum settings. Here, we propose a scheme for using quantum information, together with the assumption of stateless (i.e., reusable) hardware tokens, to build statistically secure OTMs. Via the semidefinite programming-based quantum games framework of Gutoski and Watrous [STOC 2007], we prove security for a malicious receiver making at most 0.114n adaptive queries to the token (for n the key size), in the quantum universal composability framework, but leave open the question of security against a polynomial amount of queries. Compared to alternative schemes derived from the literature on quantum money, our scheme is technologically simple since it is of the "prepare-and-measure" type. We also give two impossibility results showing certain assumptions in our scheme cannot be relaxed.}}, author = {{Broadbent, Anne and Gharibian, Sevag and Zhou, Hong-Sheng}}, issn = {{2521-327X}}, journal = {{Quantum}}, keywords = {{Physics and Astronomy (miscellaneous), Atomic and Molecular Physics, and Optics}}, publisher = {{Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften}}, title = {{{Towards Quantum One-Time Memories from Stateless Hardware}}}, doi = {{10.22331/q-2021-04-08-429}}, volume = {{5}}, year = {{2021}}, }