@article{55085, abstract = {{The lithium niobate–lithium tantalate solid solution’s phase diagram was investigated using experimental data from differential thermal analysis (DTA) and crystal growth. We used XRF analysis to determine the elemental composition of the crystals. The Neumann–Kopp rule provided essential data for the end members lithium niobate (LN) and lithium tantalate (LT). The heats of fusion of the end members, given by DTA measurements, are 103 kJ/mol at 1531 K for LN and 289 kJ/mol at 1913 K for LT. These values were used as input parameters to generate the data. This data served as the basis for calculating a phase diagram for LN-LT solid solutions. Finally, based on the experimental data and a thermodynamic solution model, the Calphad Factsage module optimized the phase diagram. We also generated thermodynamic parameters for Gibbs’ excess energy of the solid solution. A plot of the segregation coefficient as a function of Ta concentration was derived from the phase diagram.}}, author = {{Bashir, Umar and Klimm, Detlef and Rüsing, Michael and Bickermann, Matthias and Ganschow, Steffen}}, issn = {{0022-2461}}, journal = {{Journal of Materials Science}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Evaluation and thermodynamic optimization of phase diagram of lithium niobate tantalate solid solutions}}}, doi = {{10.1007/s10853-024-09932-7}}, year = {{2024}}, } @article{55140, author = {{Yasmin, Farha and Sperling, Jan}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Entanglement-assisted quantum speedup: Beating local quantum speed limits}}}, doi = {{10.1103/physreva.110.012424}}, volume = {{110}}, year = {{2024}}, } @article{55173, author = {{Di Fidio, Christian and Ares, Laura and Sperling, Jan}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Quantum walks and entanglement in cavity networks}}}, doi = {{10.1103/physreva.110.013705}}, volume = {{110}}, year = {{2024}}, } @article{55174, abstract = {{We apply principal component analysis (PCA) to a set of electrical output signals from a commercially available superconducting nanowire single-photon detector (SNSPD) to investigate their photon-number-resolving capability. We find that the rising edge as well as the amplitude of the electrical signal have the most dependence on photon number. Accurately measuring the rising edge while simultaneously measuring the voltage of the pulse amplitude maximizes the photon-number resolution of SNSPDs. Using an optimal basis of principal components, we show unambiguous discrimination between one- and two-photon events, as well as partial resolution up to five photons. This expands the use case of SNSPDs to photon-counting experiments, without the need of detector multiplexing architectures. Published by the American Physical Society 2024 }}, author = {{Schapeler, Timon and Lamberty, Niklas and Hummel, Thomas and Schlue, Fabian and Stefszky, Michael and Brecht, Benjamin and Silberhorn, Christine and Bartley, Tim}}, issn = {{2331-7019}}, journal = {{Physical Review Applied}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Electrical trace analysis of superconducting nanowire photon-number-resolving detectors}}}, doi = {{10.1103/physrevapplied.22.014024}}, volume = {{22}}, year = {{2024}}, } @article{54668, abstract = {{Samples of dielectric optical waveguides of rib or strip type in thin-film lithium niobate (TFLN) technology are characterized with respect to their optical loss using the Fabry-Pérot method. Attributing the losses mainly to sidewall roughness, we employ a simple perturbational procedure, based on rigorously computed mode profiles of idealized channels, to estimate the attenuation for waveguides with different cross sections. A single fit parameter suffices for an adequate modelling of the effect of the waveguide geometry on the loss levels.}}, author = {{Hammer, Manfred and Babel, Silia and Farheen, Henna and Padberg, Laura and Scheytt, J. Christoph and Silberhorn, Christine and Förstner, Jens}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_waveguide}}, number = {{13}}, pages = {{22878}}, publisher = {{Optica Publishing Group}}, title = {{{Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides}}}, doi = {{10.1364/oe.521766}}, volume = {{32}}, year = {{2024}}, } @article{55737, abstract = {{We report on a photonic simulator of the critical state forming at the quantum phase transition between topologically distinct Anderson insulator phases. We observe a time-staggered profile in the circular photon polarization, which originates from the interplay of a chiral and sublattice symmetry, and has recently been suggested as a signature for topological Anderson criticality within the setup. We discuss the role of statistical detuning from criticality and show that the controlled breaking of phase coherence removes the signal, revealing its origin in quantum coherence. Published by the American Physical Society 2024 }}, author = {{Barkhofen, Sonja and De, Syamsundar and Sperling, Jan and Silberhorn, Christine and Altland, Alexander and Bagrets, Dmitry and Kim, Kun Woo and Micklitz, Tobias}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{3}}, publisher = {{American Physical Society (APS)}}, title = {{{Experimental observation of topological quantum criticality}}}, doi = {{10.1103/physrevresearch.6.033194}}, volume = {{6}}, year = {{2024}}, } @inproceedings{55268, author = {{Rose, Hendrik and Sharapova, Polina R. and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XXVIII}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y.}}, publisher = {{SPIE}}, title = {{{Microscopic simulations of the dynamics of excitonic many-body correlations coupled to quantum light}}}, doi = {{10.1117/12.2690245}}, year = {{2024}}, } @article{49652, abstract = {{Broadband coherent anti-Stokes Raman scattering (BCARS) is a powerful spectroscopy method combining high signal intensity with spectral sensitivity, enabling rapid imaging of heterogeneous samples in biomedical research and, more recently, in crystalline materials. However, BCARS encounters spectral distortion due to a setup-dependent non-resonant background (NRB). This study assesses BCARS reproducibility through a round robin experiment using two distinct BCARS setups and crystalline materials with varying structural complexity, including diamond, 6H-SiC, KDP, and KTP. The analysis compares setup-specific NRB correction procedures, detected and NRB-removed spectra, and mode assignment. We determine the influence of BCARS setup parameters like pump wavelength, pulse width, and detection geometry and provide a practical guide for optimizing BCARS setups for solid-state applications.}}, author = {{Hempel, Franz and Vernuccio, Federico and König, Lukas and Buschbeck, Robin and Rüsing, Michael and Cerullo, Giulio and Polli, Dario and Eng, Lukas M.}}, issn = {{1559-128X}}, journal = {{Applied Optics}}, keywords = {{Atomic and Molecular Physics, and Optics, Engineering (miscellaneous), Electrical and Electronic Engineering}}, number = {{1}}, publisher = {{Optica Publishing Group}}, title = {{{Comparing transmission- and epi-BCARS: a round robin on solid-state materials}}}, doi = {{10.1364/ao.505374}}, volume = {{63}}, year = {{2024}}, } @inproceedings{60023, author = {{Wetter, Helene and Gao, Wenlong and Rehberg, Falk and Wingenbach, Jan and Schumacher, Stefan and Zentgraf, Thomas}}, booktitle = {{Proceedings of The 14th International Conference on Metamaterials, Photonic Crystals and Plasmonics}}, issn = {{2429-1390}}, location = {{Toyama, Japan}}, title = {{{Dielectric metasurface for wave-vector variant and circular polarization dependent transmission}}}, year = {{2024}}, } @article{32101, author = {{Weich, Tobias and Guedes Bonthonneau, Yannick and Guillarmou, Colin and Hilgert, Joachim}}, journal = {{J. Europ. Math. Soc.}}, number = {{8}}, pages = {{3085–3147}}, title = {{{Ruelle-Taylor resonances of Anosov actions}}}, doi = {{https://doi.org/10.4171/JEMS/1428}}, volume = {{27}}, year = {{2024}}, } @article{61251, abstract = {{We theoretically investigate strategies for the deterministic creation of trains of time-bin entangled photons using an individual quantum emitter described by a Λ-type electronic system. We explicitly demonstrate the theoretical generation of linear cluster states with substantial numbers of entangled photonic qubits in full microscopic numerical simulations. The underlying scheme is based on the manipulation of ground state coherences through precise optical driving. One important finding is that the most easily accessible quality metrics, the achievable rotation fidelities, fall short in assessing the actual quantum correlations of the emitted photons in the face of losses. To address this, we explicitly calculate stabilizer generator expectation values as a superior gauge for the quantum properties of the generated many-photon state. With widespread applicability in other emitter and excitation–emission schemes also, our work lays the conceptual foundations for an in-depth practical analysis of time-bin entanglement based on full numerical simulations with predictive capabilities for realistic systems and setups, including losses and imperfections. The specific results shown in the present work illustrate that with controlled minimization of losses and realistic system parameters for quantum-dot type systems, useful linear cluster states of significant lengths can be generated in the calculations, discussing the possibility of scalability for quantum information processing endeavors.}}, author = {{Bauch, David and Köcher, Nikolas and Heinisch, Nils and Schumacher, Stefan}}, issn = {{2835-0103}}, journal = {{APL Quantum}}, number = {{3}}, publisher = {{AIP Publishing}}, title = {{{Time-bin entanglement in the deterministic generation of linear photonic cluster states}}}, doi = {{10.1063/5.0214197}}, volume = {{1}}, year = {{2024}}, } @article{56267, author = {{Serino, Laura and Ridder, Werner and Bhattacharjee, Abhinandan and Gil López, Jano and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{2837-6714}}, journal = {{Optica Quantum}}, publisher = {{Optica Publishing Group}}, title = {{{Orchestrating time and color: a programmable source of high-dimensional entanglement}}}, doi = {{10.1364/opticaq.532334}}, year = {{2024}}, } @article{62849, abstract = {{AbstractAn on-demand source of bright entangled photon pairs is desirable for quantum key distribution (QKD) and quantum repeaters. The leading candidate to generate such pairs is based on spontaneous parametric down-conversion (SPDC) in non-linear crystals. However, its pair extraction efficiency is limited to 0.1% when operating at near-unity fidelity due to multiphoton emission at high brightness. Quantum dots in photonic nanostructures can in principle overcome this limit, but the devices with high entanglement fidelity (99%) have low pair extraction efficiency (0.01%). Here, we show a measured peak entanglement fidelity of 97.5% ± 0.8% and pair extraction efficiency of 0.65% from an InAsP quantum dot in an InP photonic nanowire waveguide. We show that the generated oscillating two-photon Bell state can establish a secure key for peer-to-peer QKD. Using our time-resolved QKD scheme alleviates the need to remove the quantum dot energy splitting of the intermediate exciton states in the biexciton-exciton cascade.}}, author = {{Pennacchietti, Matteo and Cunard, Brady and Nahar, Shlok and Zeeshan, Mohd and Gangopadhyay, Sayan and Poole, Philip J. and Dalacu, Dan and Fognini, Andreas and Jöns, Klaus and Zwiller, Val and Jennewein, Thomas and Lütkenhaus, Norbert and Reimer, Michael E.}}, issn = {{2399-3650}}, journal = {{Communications Physics}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution}}}, doi = {{10.1038/s42005-024-01547-3}}, volume = {{7}}, year = {{2024}}, } @inproceedings{62852, author = {{Gyger, Samuel and Tao, Max and Colangelo, Marco and Christen, Ian and Larocque, Hugo and Zichi, Julian and Schweickert, Lucas and Elshaari, Ali and Steinhauer, Stephan and Covre da Silva, Saimon and Rastelli, Armando and Sattari, Hamed and Chong, Gregory and Pétremand, Yves and Prieto, Ivan and Yu, Yang and Ghadimi, Amir and Englund, Dirk and Jöns, Klaus and Zwiller, Val and Errando Herranz, Carlos}}, booktitle = {{Quantum Computing, Communication, and Simulation IV}}, editor = {{Hemmer, Philip R. and Migdall, Alan L.}}, publisher = {{SPIE}}, title = {{{Integrating superconducting single-photon detectors into active photonic circuits}}}, doi = {{10.1117/12.3009736}}, year = {{2024}}, } @inproceedings{62850, author = {{Mikitta, Telsche and Cutuk, Ana and Jetter, Michael and Michler, Peter and Jöns, Klaus and Kahle, Hermann}}, booktitle = {{Vertical External Cavity Surface Emitting Lasers (VECSELs) XIII}}, editor = {{Keller, Ursula}}, publisher = {{SPIE}}, title = {{{Membrane external-cavity surface-emitting lasers (MECSELs) optimized for double-side-pumping: a first fundamental single-side pumping characterization}}}, doi = {{10.1117/12.3002481}}, year = {{2024}}, } @article{52876, author = {{Arends, Christian and Wolf, Lasse Lennart and Meinecke, Jasmin and Barkhofen, Sonja and Weich, Tobias and Bartley, Tim}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, keywords = {{General Physics and Astronomy}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Decomposing large unitaries into multimode devices of arbitrary size}}}, doi = {{10.1103/physrevresearch.6.l012043}}, volume = {{6}}, year = {{2024}}, } @article{62868, abstract = {{We theoretically investigate strategies for the deterministic creation of trains of time-bin entangled photons using an individual quantum emitter described by a Λ-type electronic system. We explicitly demonstrate the theoretical generation of linear cluster states with substantial numbers of entangled photonic qubits in full microscopic numerical simulations. The underlying scheme is based on the manipulation of ground state coherences through precise optical driving. One important finding is that the most easily accessible quality metrics, the achievable rotation fidelities, fall short in assessing the actual quantum correlations of the emitted photons in the face of losses. To address this, we explicitly calculate stabilizer generator expectation values as a superior gauge for the quantum properties of the generated many-photon state. With widespread applicability in other emitter and excitation–emission schemes also, our work lays the conceptual foundations for an in-depth practical analysis of time-bin entanglement based on full numerical simulations with predictive capabilities for realistic systems and setups, including losses and imperfections. The specific results shown in the present work illustrate that with controlled minimization of losses and realistic system parameters for quantum-dot type systems, useful linear cluster states of significant lengths can be generated in the calculations, discussing the possibility of scalability for quantum information processing endeavors.}}, author = {{Bauch, David and Köcher, Nikolas and Heinisch, Nils and Schumacher, Stefan}}, issn = {{2835-0103}}, journal = {{APL Quantum}}, number = {{3}}, publisher = {{AIP Publishing}}, title = {{{Time-bin entanglement in the deterministic generation of linear photonic cluster states}}}, doi = {{10.1063/5.0214197}}, volume = {{1}}, year = {{2024}}, } @article{62853, abstract = {{Abstract Developing coherent excitation methods for quantum emitters ensuring high brightness, optimal single‐photon purity and indistinguishability of the emitted photons has been a key challenge in the past years. While various methods have been proposed and explored, they all have specific advantages and disadvantages. This study investigates the dynamics of the recent swing‐up scheme as an excitation method for a two‐level system and its performance in single‐photon generation. By applying two far red‐detuned laser pulses, the two‐level system can be prepared in the excited state with near‐unity fidelity. The successful operation and coherent character of this technique are demonstrated using a semiconductor quantum dot (QD). Moreover, the multi‐dimensional parameter space of the two laser pulses is explored to analyze its impact on excitation fidelity. Finally, the performance of the scheme as an excitation method for generating high‐quality single photons is analyzed. The swing‐up scheme itself proves effective, exhibiting nearly perfect single‐photon purity, while the observed indistinguishability in the studied sample is limited by the influence of the inevitable high excitation powers on the semiconductor environment of the quantum dot.}}, author = {{Boos, Katarina and Sbresny, Friedrich and Kim, Sang Kyu and Kremser, Malte and Riedl, Hubert and Bopp, Frederik W. and Rauhaus, William and Scaparra, Bianca and Jöns, Klaus and Finley, Jonathan J. and Müller, Kai and Hanschke, Lukas}}, issn = {{2511-9044}}, journal = {{Advanced Quantum Technologies}}, number = {{4}}, publisher = {{Wiley}}, title = {{{Coherent Swing‐Up Excitation for Semiconductor Quantum Dots}}}, doi = {{10.1002/qute.202300359}}, volume = {{7}}, year = {{2024}}, } @unpublished{62858, abstract = {{Phonons in solid-state quantum emitters play a crucial role in their performance as photon sources in quantum technology. For resonant driving, phonons dampen the Rabi oscillations resulting in reduced preparation fidelities. The phonon spectral density, which quantifies the strength of the carrier-phonon interaction, is non-monotonous as a function of energy. As one of the most prominent consequences, this leads to the reappearance of Rabi rotations for increasing pulse power, which was theoretically predicted in Phys. Rev. Lett. 98, 227403 (2007). In this paper we present the experimental demonstration of the reappearance of Rabi rotations.}}, author = {{Hanschke, L. and Bracht, T. K. and Schöll, E. and Bauch, David and Berger, Eva and Kallert, Patricia and Peter, M. and Garcia, A. J. and Silva, S. F. Covre da and Manna, S. and Rastelli, A. and Schumacher, Stefan and Reiter, D. E. and Jöns, Klaus}}, booktitle = {{arXiv:2409.19167}}, title = {{{Experimental measurement of the reappearance of Rabi rotations in semiconductor quantum dots}}}, year = {{2024}}, } @unpublished{62856, abstract = {{On-chip emitters that can generate single and entangled photons are essential building blocks for developing photonic quantum information processing technologies in a scalable fashion. Semiconductor quantum dots (QDs) are attractive candidates that emit high-quality quantum states of light on demand, however at a rate limited by their spontaneous radiative lifetime. In this study, we utilize the Purcell effect to demonstrate up to a 38-fold enhancement in the emission rate of InAs QDs by coupling them to metal-clad GaAs nanopillars. These cavities, featuring a sub-wavelength mode volume of 4.5x10-4 (λ/n)3 and low quality factor of 62, enable Purcell-enhanced single-photon emission across a large bandwidth of 15 nm. The broadband nature of the cavity eliminates the need for implementing tuning mechanisms typically required to achieve QD-cavity resonance, thus relaxing fabrication constraints. Ultimately, this QD-cavity architecture represents a significant stride towards developing solid-state quantum emitters generating near-ideal single-photon states at GHz-level repetition rates.}}, author = {{Jöns, Klaus}}, title = {{{Purcell-enhanced single-photon emission from InAs/GaAs quantum dots coupled to broadband cylindrical nanocavities}}}, year = {{2024}}, }