@article{34700, author = {{Gharibian, Sevag and Santha, Miklos and Sikora, Jamie and Sundaram, Aarthi and Yirka, Justin}}, issn = {{1016-3328}}, journal = {{Computational Complexity}}, keywords = {{Computational Mathematics, Computational Theory and Mathematics, General Mathematics, Theoretical Computer Science}}, number = {{2}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Quantum generalizations of the polynomial hierarchy with applications to QMA(2)}}}, doi = {{10.1007/s00037-022-00231-8}}, volume = {{31}}, year = {{2022}}, } @inproceedings{27160, abstract = {{We study the complexity of problems solvable in deterministic polynomial time with access to an NP or Quantum Merlin-Arthur (QMA)-oracle, such as $P^{NP}$ and $P^{QMA}$, respectively. The former allows one to classify problems more finely than the Polynomial-Time Hierarchy (PH), whereas the latter characterizes physically motivated problems such as Approximate Simulation (APX-SIM) [Ambainis, CCC 2014]. In this area, a central role has been played by the classes $P^{NP[\log]}$ and $P^{QMA[\log]}$, defined identically to $P^{NP}$ and $P^{QMA}$, except that only logarithmically many oracle queries are allowed. Here, [Gottlob, FOCS 1993] showed that if the adaptive queries made by a $P^{NP}$ machine have a "query graph" which is a tree, then this computation can be simulated in $P^{NP[\log]}$. In this work, we first show that for any verification class $C\in\{NP,MA,QCMA,QMA,QMA(2),NEXP,QMA_{\exp}\}$, any $P^C$ machine with a query graph of "separator number" $s$ can be simulated using deterministic time $\exp(s\log n)$ and $s\log n$ queries to a $C$-oracle. When $s\in O(1)$ (which includes the case of $O(1)$-treewidth, and thus also of trees), this gives an upper bound of $P^{C[\log]}$, and when $s\in O(\log^k(n))$, this yields bound $QP^{C[\log^{k+1}]}$ (QP meaning quasi-polynomial time). We next show how to combine Gottlob's "admissible-weighting function" framework with the "flag-qubit" framework of [Watson, Bausch, Gharibian, 2020], obtaining a unified approach for embedding $P^C$ computations directly into APX-SIM instances in a black-box fashion. Finally, we formalize a simple no-go statement about polynomials (c.f. [Krentel, STOC 1986]): Given a multi-linear polynomial $p$ specified via an arithmetic circuit, if one can "weakly compress" $p$ so that its optimal value requires $m$ bits to represent, then $P^{NP}$ can be decided with only $m$ queries to an NP-oracle.}}, author = {{Gharibian, Sevag and Rudolph, Dorian}}, booktitle = {{13th Innovations in Theoretical Computer Science (ITCS 2022)}}, number = {{75}}, pages = {{1--27}}, title = {{{On polynomially many queries to NP or QMA oracles}}}, doi = {{10.4230/LIPIcs.ITCS.2022.75}}, volume = {{215}}, year = {{2022}}, } @article{28254, abstract = {{With the rapid advances of functional dielectric metasurfaces and their integration on on-chip nanophotonic devices, the necessity of metasurfaces working in different environments, especially in biological applications, arose. However, the metasurfaces’ performance is tied to the unit cell’s efficiency and ultimately the surrounding environment it was designed for, thus reducing its applicability if exposed to altering refractive index media. Here, we report a method to increase a metasurface’s versatility by covering the high-index metasurface with a low index porous SiO2 film, protecting the metasurface from environmental changes while keeping the working efficiency unchanged. We show, that a covered metasurface retains its functionality even when exposed to fluidic environments.}}, author = {{Geromel, René and Weinberger, Christian and Brormann, Katja and Tiemann, Michael and Zentgraf, Thomas}}, issn = {{2159-3930}}, journal = {{Optical Materials Express}}, number = {{1}}, pages = {{13--21}}, publisher = {{Optica}}, title = {{{Porous SiO2 coated dielectric metasurface with consistent performance independent of environmental conditions}}}, doi = {{10.1364/ome.444264}}, volume = {{12}}, year = {{2022}}, } @article{37318, abstract = {{Abstract The interaction between quantum light and matter is being intensively studied for systems that are enclosed in high-Q cavities which strongly enhance the light–matter coupling. Cavities with low Q-factors are generally given less attention due to their high losses that quickly destroy quantum systems. However, bad cavities can be utilized for several applications, where lower Q-factors are required, e.g., to increase the spectral width of the cavity mode. In this work, we demonstrate that low-Q cavities can be beneficial for preparing specific electronic steady states when certain quantum states of light are applied. We investigate the interaction between quantum light with various statistics and matter represented by a Λ-type three-level system in lossy cavities, assuming that cavity losses are the dominant loss mechanism. We show that cavity losses lead to non-trivial electronic steady states that can be controlled by the loss rate and the initial statistics of the quantum fields. We discuss the mechanism of the formation of such steady states on the basis of the equations of motion and present both analytical expressions and numerical simulations for such steady states.}}, author = {{Rose, Hendrik and Tikhonova, O V and Meier, Torsten and Sharapova, Polina}}, issn = {{1367-2630}}, journal = {{New Journal of Physics}}, keywords = {{General Physics and Astronomy}}, number = {{6}}, publisher = {{IOP Publishing}}, title = {{{Steady states of Λ-type three-level systems excited by quantum light with various photon statistics in lossy cavities}}}, doi = {{10.1088/1367-2630/ac74d8}}, volume = {{24}}, year = {{2022}}, } @article{37319, author = {{Grisard, S. and Rose, Hendrik and Trifonov, A. V. and Reichhardt, R. and Reiter, D. E. and Reichelt, Matthias and Schneider, C. and Kamp, M. and Höfling, S. and Bayer, M. and Meier, Torsten and Akimov, I. A.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{20}}, publisher = {{American Physical Society (APS)}}, title = {{{Multiple Rabi rotations of trions in InGaAs quantum dots observed by photon echo spectroscopy with spatially shaped laser pulses}}}, doi = {{10.1103/physrevb.106.205408}}, volume = {{106}}, year = {{2022}}, } @inproceedings{37329, author = {{Trautmann, Alexander and Zuo, Ruixin and Wang, Guifang and Hannes, Wolf-Rüdiger and Yang, Shidong and Thong, Le Huu and Ngo, Cong and Steiner, Johannes and Ciappina, Marcelo and Reichelt, Matthias and Duc, Huynh Thanh and Song, Xiaohong and Yang, Weifeng and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XXVI}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y.}}, title = {{{Microscopic simulations of high harmonic generation from semiconductors}}}, doi = {{10.1117/12.2607447}}, volume = {{11999}}, year = {{2022}}, } @inproceedings{37327, author = {{Rose, Hendrik and Tikhonova, Olga V. and Meier, Torsten and Sharapova, Polina}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XXVI}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y.}}, title = {{{Theoretical analysis of correlations between two quantum fields exciting a three-level system using the cluster-expansion approach}}}, doi = {{10.1117/12.2608528}}, volume = {{11999}}, year = {{2022}}, } @article{37323, author = {{Paul, J. and Rose, Hendrik and Swagel, E. and Meier, Torsten and Wahlstrand, J. K. and Bristow, A. D.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{11}}, publisher = {{American Physical Society (APS)}}, title = {{{Coherent contributions to population dynamics in a semiconductor microcavity}}}, doi = {{10.1103/physrevb.105.115307}}, volume = {{105}}, year = {{2022}}, } @unpublished{37325, author = {{Meier, Torsten and Ali, Usman}}, booktitle = {{Condensed Matter}}, title = {{{Super-Bloch oscillations with parametric modulation of a parabolic trap}}}, year = {{2022}}, } @article{40523, abstract = {{AbstractTailored nanoscale quantum light sources, matching the specific needs of use cases, are crucial building blocks for photonic quantum technologies. Several different approaches to realize solid-state quantum emitters with high performance have been pursued and different concepts for energy tuning have been established. However, the properties of the emitted photons are always defined by the individual quantum emitter and can therefore not be controlled with full flexibility. Here we introduce an all-optical nonlinear method to tailor and control the single photon emission. We demonstrate a laser-controlled down-conversion process from an excited state of a semiconductor quantum three-level system. Based on this concept, we realize energy tuning and polarization control of the single photon emission with a control-laser field. Our results mark an important step towards tailored single photon emission from a photonic quantum system based on quantum optical principles.}}, author = {{Jonas, B. and Heinze, Dirk Florian and Schöll, E. and Kallert, P. and Langer, T. and Krehs, S. and Widhalm, A. and Jöns, Klaus and Reuter, Dirk and Schumacher, Stefan and Zrenner, Artur}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, keywords = {{General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Nonlinear down-conversion in a single quantum dot}}}, doi = {{10.1038/s41467-022-28993-3}}, volume = {{13}}, year = {{2022}}, } @article{40431, author = {{Praschan, Tom and Heinze, Dirk and Breddermann, Dominik and Zrenner, Artur and Walther, Andrea and Schumacher, Stefan}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{4}}, publisher = {{American Physical Society (APS)}}, title = {{{Pulse shaping for on-demand emission of single Raman photons from a quantum-dot biexciton}}}, doi = {{10.1103/physrevb.105.045302}}, volume = {{105}}, year = {{2022}}, } @misc{40428, author = {{Jonas, Björn and Heinze, Dirk Florian and Schöll, Eva and Kallert, Patricia and Langer, Timo and Krehs, Sebastian and Widhalm, Alex and Jöns, Klaus and Reuter, Dirk and Zrenner, Artur}}, publisher = {{LibreCat University}}, title = {{{Nonlinear down-conversion in a single quantum dot}}}, doi = {{10.5281/ZENODO.6024228}}, year = {{2022}}, } @article{37711, abstract = {{AbstractPolarons influence decisively the performance of lithium niobate for optical applications. In this work, the formation of (defect) bound polarons in lithium niobate is studied by ab initio molecular dynamics. The calculations show a broad scatter of polaron formation times. Rising temperature increases the share of trajectories with long formation times, which leads to an overall increase of the average formation time with temperature. However, even at elevated temperatures, the average formation time does not exceed the value of 100 femtoseconds, i.e., a value close to the time measured for free, i.e., self-trapped polarons. Analyzing individual trajectories, it is found that the time required for the structural relaxation of the polarons depends sensitively on the excitation of the lithium niobate high-frequency phonon modes and their phase relation.}}, author = {{Krenz, Marvin and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{0947-8396}}, journal = {{Applied Physics A}}, keywords = {{General Materials Science, General Chemistry}}, pages = {{480}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Bound polaron formation in lithium niobate from ab initio molecular dynamics}}}, doi = {{10.1007/s00339-022-05577-y}}, volume = {{128}}, year = {{2022}}, } @inproceedings{43744, abstract = {{We demonstrate theoretically and experimentally complex correlations in the photon numbers of two-mode quantum states using measurement-induced nonlinearity. For this, we combine the interference of coherent states and single photons with photon sub-traction.}}, author = {{Meier, Torsten and Hoepker, Jan Philipp and Protte, Maximilian and Eigner, Christof and Silberhorn, Christine and Sharapova, Polina R. and Sperling, Jan and Bartley, Tim}}, booktitle = {{Conference on Lasers and Electro-Optics: Applications and Technology}}, isbn = {{978-1-957171-05-0}}, location = {{San Jose, California United States}}, pages = {{JTu3A. 17}}, publisher = {{Optica Publishing Group}}, title = {{{Two-Mode Photon-Number Correlations Created by Measurement-Induced Nonlinearity}}}, doi = {{10.1364/CLEO_AT.2022.JTu3A.17}}, year = {{2022}}, } @article{33484, abstract = {{We study the DC conductivity in potassium titanyl phosphate (KTiOPO4, KTP) and its isomorphs KTiOAsO4 (KTA) and Rb1%K99%TiOPO4 (RKTP) and introduce a method by which to reduce the overall ionic conductivity in KTP by a potassium nitrate treatment. Furthermore, we create so-called gray tracking in KTP and investigate the ionic conductivity in theses areas. A local unintended reduction of the ionic conductivity is observed in the gray-tracked regions, which also induce additional optical absorption in the material. We show that a thermal treatment in an oxygen-rich atmosphere removes the gray tracking and brings the ionic conductivity as well as the optical transmission back to the original level. These studies can help to choose the best material and treatment for specific applications.}}, author = {{Padberg, Laura and Quiring, Viktor and Bocchini, Adriana and Santandrea, Matteo and Gerstmann, Uwe and Schmidt, Wolf Gero and Silberhorn, Christine and Eigner, Christof}}, issn = {{2073-4352}}, journal = {{Crystals}}, pages = {{1359}}, title = {{{DC Ionic Conductivity in KTP and Its Isomorphs: Properties, Methods for Suppression, and Its Connection to Gray Tracking}}}, doi = {{10.3390/cryst12101359}}, volume = {{12}}, year = {{2022}}, } @article{34074, author = {{Mahnken, Rolf and Mirzapour, Jamil}}, issn = {{0939-1533}}, journal = {{Archive of Applied Mechanics}}, keywords = {{Mechanical Engineering}}, number = {{11}}, pages = {{3295--3323}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{A statistically based strain energy function for polymer chains in rubber elasticity}}}, doi = {{10.1007/s00419-022-02237-8}}, volume = {{92}}, year = {{2022}}, } @inproceedings{30389, abstract = {{Online solvers for a series of standard 1-D or 2-D problems in integrated optics will be discussed. Implemented on the basis of HTML/JavaScript/SVG with core routines compiled from well tested C++-sources, the quasi-analytical algorithms require a computational load that can be handled easily even by current mobile devices. So far the series covers the 1-D guided modes of dielectric multilayer slab waveguides and the oblique plane wave reflection from these, the modes of rectangular channel waveguides (in an approximation of effective indices), bend modes of curved multilayer slabs, whispering-gallery resonances (“Quasi-Normal-Modes”) supported by circular dielectric cavities, the hybrid modes of circular multi-step-index optical fibers, bound and leaky modes of 1-D complex multilayers, including plasmonic surface modes, and, with restrictions, quite general rectangular scattering problems in 2-D.}}, author = {{Hammer, Manfred}}, booktitle = {{Integrated Optics: Devices, Materials, and Technologies XXVI}}, editor = {{García-Blanco, Sonia M. and Cheben, Pavel}}, keywords = {{tet_topic_waveguide}}, pages = {{1200414}}, publisher = {{SPIE}}, title = {{{Small-scale online simulations in guided-wave photonics}}}, doi = {{10.1117/12.2612208}}, year = {{2022}}, } @article{26627, abstract = {{Many-body perturbation theory based on density-functional theory calculations is used to determine the quasiparticle band structures and the dielectric functions of the isomorphic ferroelectrics rubidium titanyl phosphate (RbTiOPO4) and potassium titanyl arsenide (KTiOAsO4). Self-energy corrections of more than 2 eV are found to widen the transport band gaps of both materials considerably to 5.3 and 5.2 eV, respectively. At the same time, both materials are characterized by strong exciton binding energies of 1.4 and 1.5 eV, respectively. The solution of the Bethe-Salpeter equation based on the quasiparticle energies results in onsets of the optical absorption within the range of the measured data.}}, author = {{Neufeld, Sergej and Schindlmayr, Arno and Schmidt, Wolf Gero}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4}}}, doi = {{10.1088/2515-7639/ac3384}}, volume = {{5}}, year = {{2022}}, } @article{37656, author = {{Glahn, Luis Joel and Ruiz Alvarado, Isaac Azahel and Neufeld, Sergej and Zare Pour, Mohammad Amin and Paszuk, Agnieszka and Ostheimer, David and Shekarabi, Sahar and Romanyuk, Oleksandr and Moritz, Dominik Christian and Hofmann, Jan Philipp and Jaegermann, Wolfram and Hannappel, Thomas and Schmidt, Wolf Gero}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, keywords = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}}, number = {{11}}, publisher = {{Wiley}}, title = {{{Clean and Hydrogen‐Adsorbed AlInP(001) Surfaces: Structures and Electronic Properties}}}, doi = {{10.1002/pssb.202200308}}, volume = {{259}}, year = {{2022}}, } @article{37710, author = {{Ruiz Alvarado, Isaac Azahel and Schmidt, Wolf Gero}}, issn = {{2470-1343}}, journal = {{ACS Omega}}, keywords = {{General Chemical Engineering, General Chemistry}}, number = {{23}}, pages = {{19355--19364}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Water/InP(001) from Density Functional Theory}}}, doi = {{10.1021/acsomega.2c00948}}, volume = {{7}}, year = {{2022}}, }