@misc{63050, author = {{Güsken, Nicholas Alexander}}, title = {{{Beam steering device and electronic apparatus including the same}}}, year = {{2025}}, } @article{62269, abstract = {{The titanium in-diffused lithium niobate waveguide platform is well-established for reliable prototyping and packaging of many quantum photonic components at room temperature. Nevertheless, compatibility with certain quantum light sources and superconducting detectors requires operation under cryogenic conditions. We characterize alterations in phase-matching and mode guiding of a non-degenerate spontaneous parametric down-conversion process emitting around 1556 nm and 950 nm, under cryogenic conditions. Despite the effects of pyroelectricity and photorefraction, the spectral properties match our theoretical model. Nevertheless, these effects cause small but significant variations within and between cooling cycles. These measurements provide a first benchmark against which other nonlinear photonic integration platforms, such as thin-film lithium niobate, can be compared.}}, author = {{Lange, Nina Amelie and Lengeling, Sebastian and Mues, Philipp and Quiring, Viktor and Ridder, Werner and Eigner, Christof and Herrmann, Harald and Silberhorn, Christine and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{24}}, publisher = {{Optica Publishing Group}}, title = {{{Widely non-degenerate nonlinear frequency conversion in cryogenic titanium in-diffused lithium niobate waveguides}}}, doi = {{10.1364/oe.578108}}, volume = {{33}}, year = {{2025}}, } @article{60466, author = {{Brockmeier, Julian and Schapeler, Timon and Lange, Nina Amelie and Höpker, Jan Philipp and Herrmann, Harald and Silberhorn, Christine and Bartley, Tim}}, journal = {{New Journal of Physics}}, title = {{{Harnessing temporal dispersion for integrated pump filtering in spontaneous heralded single-photon generation processes}}}, doi = {{10.1088/1367-2630/ade46c}}, 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}}, } @article{62861, author = {{Laneve, Alessandro and Ronco, Giuseppe and Beccaceci, Mattia and Barigelli, Paolo and Salusti, Francesco and Claro-Rodriguez, Nicolas and De Pascalis, Giorgio and Suprano, Alessia and Chiaudano, Leone and Schöll, Eva and Hanschke, Lukas and Krieger, Tobias M. and Buchinger, Quirin and Covre da Silva, Saimon F. and Neuwirth, Julia and Stroj, Sandra and Höfling, Sven and Huber-Loyola, Tobias and Usuga Castaneda, Mario A. and Carvacho, Gonzalo and Spagnolo, Nicolò and Rota, Michele B. and Basso Basset, Francesco and Rastelli, Armando and Sciarrino, Fabio and Jöns, Klaus and Trotta, Rinaldo}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Quantum teleportation with dissimilar quantum dots over a hybrid quantum network}}}, doi = {{10.1038/s41467-025-65911-9}}, volume = {{16}}, year = {{2025}}, } @article{63192, abstract = {{Lithium niobate (LiNbO3) is a widely used material with several desirable physical properties, such as high second-order nonlinear optical and strong electro-optical effects. Thus LiNbO3 is used for various applications such as electro-optic modulation or nonlinear frequency conversion and mixing. But LiNbO3 also exhibits a strong photorefractive effect, which limits the intensity of the optical fields involved. Various approaches to reduce the photorefractive effect have been investigated, such as increasing the temperature, doping the crystal or using different waveguide designs in LiNbO3. Here, we present an analysis of the approach to increase the photorefractive damage threshold by using different waveguide designs. Contrary to previous claims and investigations, our SHG measurements revealed no significant difference in resistance to photorefractive damage when comparing conventional Ti-doped channel waveguides and Ti-doped diced ridge waveguides in LiNbO3. Furthermore, we have investigated the effect of photorefractive cleaning and curing using a light field at 532 nm. Here, we observe a reduction in the photorefractive effect at room temperature during and after SHG measurements, which is an easy alternative to conventional approaches.}}, author = {{Kirsch, Michelle and Kießler, Christian and Lengeling, Sebastian and Stefszky, Michael and Eigner, Christof and Herrmann, Harald and Silberhorn, Christine}}, issn = {{0030-3992}}, journal = {{Optics & Laser Technology}}, publisher = {{Elsevier BV}}, title = {{{Photorefraction and in-situ optical cleaning in various types of LiNbO3 waveguides}}}, doi = {{10.1016/j.optlastec.2025.114260}}, volume = {{193}}, year = {{2025}}, } @article{63213, abstract = {{Quantum uncertainty relations impose fundamental limits on the joint knowledge that can be acquired from complementary observables: Perfect knowledge of a quantum state in one basis implies maximal indetermination in all other mutually unbiased bases (MUBs). Uncertainty relations derived from joint properties of the MUBs are generally assumed to be uniform, irrespective of the specific observables chosen within a set. In this work, we demonstrate instead that the uncertainty relations can depend on the choice of observables. Through both experimental observation and numerical methods, we show that selecting different sets of three MUBs in a five-dimensional quantum system results in distinct uncertainty bounds, i.e., in varying degrees of complementarity, in terms of both entropy and variance.}}, author = {{Serino, Laura Maria and Chesi, Giovanni and Brecht, Benjamin and Maccone, Lorenzo and Macchiavello, Chiara and Silberhorn, Christine}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{3}}, publisher = {{American Physical Society (APS)}}, title = {{{Complementarity-based complementarity: The choice of mutually unbiased observables shapes quantum uncertainty relations}}}, doi = {{10.1103/v24q-sl6n}}, volume = {{7}}, year = {{2025}}, } @article{63214, 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 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{63215, abstract = {{Abstract High-dimensional time-frequency encodings have the potential to significantly advance quantum information science; however, practical applications require precise knowledge of the encoded quantum states, which becomes increasingly challenging for larger Hilbert spaces. Self-guided tomography (SGT) has emerged as a practical and scalable technique for this purpose in the spatial domain. Here, we apply SGT to estimate time-frequency states using a multi-output quantum pulse gate. We achieve fidelities of more than 99% for 3- and 5-dimensional states without the need for calibration or post-processing. We demonstrate the robustness of SGT against statistical and environmental noise, highlighting its efficacy in the photon-starved regime typical of quantum information applications.}}, author = {{Serino, Laura Maria and Rambach, Markus and Brecht, Benjamin and Romero, Jacquiline and Silberhorn, Christine}}, issn = {{2058-9565}}, journal = {{Quantum Science and Technology}}, number = {{2}}, publisher = {{IOP Publishing}}, title = {{{Self-guided tomography of time-frequency qudits}}}, doi = {{10.1088/2058-9565/adb0ea}}, volume = {{10}}, year = {{2025}}, } @article{63091, abstract = {{We present the design and characterization of a guided-wave, bright, and highly frequency non-degenerate parametric down-conversion (PDC) source in thin-film lithium niobate. The source generates photon pairs with wavelengths of 815 nm and 1550 nm, linking the visible wavelength regime with telecommunication wavelengths. We confirm the high quality of the generated single photons by determining a value for the heralded second-order correlation function as low as g_h^(2)=(6.7+/-1.1)*10^8-3). Furthermore, we achieve a high spectral brightness of 0.44·10pairs/(smWGHz) which is two orders of magnitude higher than sources based on weakly guiding waveguides. The shape of the PDC spectrum and the strong agreement between the effective and nominal bandwidth highlight our high fabrication quality of periodically poled waveguides. The good agreement between the measured and simulated spectral characteristics of our source demonstrates our excellent understanding of the PDC process. Our result is a valuable step towards practical and scalable quantum communication networks as well as photonic quantum computing.}}, author = {{Babel, Silia and Bollmers, Laura and Roeder, Franz and Ridder, Werner and Golla, Christian and Köthemann, Ronja and Reineke, Bernhard and Herrmann, Harald and Brecht, Benjamin and Eigner, Christof and Padberg, Laura and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{25}}, publisher = {{Optica Publishing Group}}, title = {{{Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths}}}, doi = {{10.1364/oe.571605}}, volume = {{33}}, year = {{2025}}, } @article{62713, abstract = {{Periodically poled thin-film lithium niobate (TFLN) crystals are the fundamental building block for highly-efficient quantum light sources and frequency converters. The efficiency of these devices is strongly dependent on the interaction length between the light and the nonlinear material, scaling quadratically with this parameter. Nevertheless, the fabrication of long, continuously poled areas in TFLN remains challenging, the length of continuously poled areas rarely exceeds 10 mm. In this work, we demonstrate a significant progress in this field achieving the periodic poling of continuous poled areas of 70 mm length with a 3 μm poling period and a close to 50 % duty cycle. We compare two poling electrode design approaches to fabricate long, continuous poled areas. The first approach involves the poling of a single, continuous 70 mm long electrode. The second utilize a segmented approach including the poling of more than 20 individual sections forming together a 70 mm long poling area with no stitching errors. While the continuous electrode allows for faster fabrication, the segmented approach allows to individually optimize the poling resulting in less duty cycle variation. A detailed analysis of the periodic poling results reveals that the results of both are consistent with previously reported poling outcomes for shorter devices. Thus, we demonstrate wafer-scale periodic poling exceeding chiplet-size without any loss in the periodic poling quality. Our work presents a key step towards highly-efficient, narrow-bandwidth and low-pump power nonlinear optical devices.}}, author = {{Bollmers, Laura and Spiegelberg, Noah and Rüsing, Michael and Eigner, Christof and Padberg, Laura and Silberhorn, Christine}}, issn = {{2192-8606}}, journal = {{Nanophotonics}}, pages = {{4761}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Segmented finger electrodes to optimize ultra-long continuous wafer-scale periodic poling in thin-film lithium niobate}}}, doi = {{10.1515/nanoph-2025-0461}}, volume = {{14}}, year = {{2025}}, } @misc{63051, author = {{Güsken, Nicholas Alexander}}, title = {{{Optical modulator and electronic apparatus including the same}}}, year = {{2025}}, } @article{63534, abstract = {{Boson sampling is a key candidate for demonstrating quantum advantage and has already yielded significant advances in quantum simulation, machine learning, and graph theory. In this work, a unification and extension of distinct forms of boson sampling is developed. The devised protocol merges discrete-variable scattershot boson sampling with continuous-variable Gaussian boson sampling. Therefore, it is rendered possible to harness the complexity of more interesting states, such as squeezed photons, in advanced sampling protocols. A generating function formalism is developed for the joint description of multiphoton and multimode light undergoing Gaussian transformations. The resulting analytical tools enable one to explore interfaces of different photonic quantum-information-processing platforms. A numerical simulation of unified sampling is carried out, benchmarking its performance, complexity, and scalability. Entanglement is characterized to exemplify the generation of quantum correlations from the nonlinear interactions of a unified sampler.}}, author = {{Bianchi, Luca and Marconi, Carlo and Ares, Laura and Bacco, Davide and Sperling, Jan}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{4}}, publisher = {{American Physical Society (APS)}}, title = {{{Unified boson sampling}}}, doi = {{10.1103/8hy1-m5gg}}, volume = {{7}}, year = {{2025}}, } @article{63562, abstract = {{Entangled two-mode Gaussian states constitute an important building block for continuous variable quantum computing and communication protocols. In this work, we theoretically study two-mode bipartite states, which are extracted from multimode light generated via type-II parametric downconversion (PDC) in lossy waveguides. For these states, we demonstrate that the squeezing quantifies entanglement and we construct a measurement basis, which results in the maximal bipartite entanglement. We illustrate our findings by numerically solving the spatial master equation for PDC in a Markovian environment. The optimal measurement modes are compared with two widely used broadband bases: the Mercer–Wolf basis (the first-order coherence basis) and the Williamson–Euler basis.}}, author = {{Kopylov, Denis and Meier, Torsten and Sharapova, Polina R.}}, issn = {{2835-0103}}, journal = {{APL Quantum}}, number = {{4}}, publisher = {{AIP Publishing}}, title = {{{Bipartite entanglement extracted from multimode squeezed light generated in lossy waveguides}}}, doi = {{10.1063/5.0293116}}, volume = {{2}}, 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}}, } @inproceedings{59896, abstract = {{We present an electronic-photonic co-designed Mach-Zehnder modulator with linear segment drivers in a photonic SOI-CMOS technology with an EO 3-dB bandwidth of ≥ 27 GHz and data transmission up to 64 Gbit/s without pre-emphasis.}}, author = {{Kress, Christian and Schwabe, Tobias and Mihaylov, Martin Miroslavov and Scheytt, J. Christoph}}, location = {{Long Beach, CA, USA}}, title = {{{High-Speed Mach-Zehnder Modulator with Linear Segmented On-Chip Drivers in Photonic 45nm SOI-CMOS Technology }}}, 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}}, } @inproceedings{59895, abstract = {{The generation of optically broadband Nyquist pulse sequences using an integrated Mach-Zehnder modulator (MZM) in a thin-film lithium-niobate (TFLN) platform with repetition rates of 5 to 32 GHz and optical bandwidths of up to 160 GHz is demonstrated. Nyquist pulse sequences with high optical bandwidth can be used as synchronization and control signals in quantum sources based on photon pair generation.}}, author = {{Kress, Christian and Mihaylov, Martin Miroslavov and Schwabe, Tobias and Silberhorn, Christine and Scheytt, J. Christoph}}, booktitle = {{PIERS Proceedings }}, location = {{Abu Dhabi}}, publisher = {{PhotonIcs and Electromagnetics Research Symposium (PIERS)}}, title = {{{Broadband Nyquist Pulse Generation on TFLN Platform for Integrated Quantum Source}}}, doi = {{10.1109/PIERS-Spring66516.2025.11276835}}, year = {{2025}}, } @unpublished{61778, abstract = {{Understanding the entanglement structure of local Hamiltonian ground spaces is a physically motivated problem, with applications ranging from tensor network design to quantum error-correcting codes. To this end, we study the complexity of estimating ground state entanglement, and more generally entropy estimation for low energy states and Gibbs states. We find, in particular, that the classes qq-QAM [Kobayashi, le Gall, Nishimura, SICOMP 2019] (a quantum analogue of public-coin AM) and QMA(2) (QMA with unentangled proofs) play a crucial role for such problems, showing: (1) Detecting a high-entanglement ground state is qq-QAM-complete, (2) computing an additive error approximation to the Helmholtz free energy (equivalently, a multiplicative error approximation to the partition function) is in qq-QAM, (3) detecting a low-entanglement ground state is QMA(2)-hard, and (4) detecting low energy states which are close to product states can range from QMA-complete to QMA(2)-complete. Our results make progress on an open question of [Bravyi, Chowdhury, Gosset and Wocjan, Nature Physics 2022] on free energy, and yield the first QMA(2)-complete Hamiltonian problem using local Hamiltonians (cf. the sparse QMA(2)-complete Hamiltonian problem of [Chailloux, Sattath, CCC 2012]).}}, author = {{Gharibian, Sevag and Kamminga, Jonas}}, booktitle = {{arXiv:2510.06796}}, title = {{{On the complexity of estimating ground state entanglement and free energy}}}, year = {{2025}}, }