@article{37338,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Methylammonium lead iodide perovskite (MAPbI<jats:sub>3</jats:sub>) is renowned for an impressive power conversion efficiency rise and cost-effective fabrication for photovoltaics. In this work, we demonstrate that polycrystalline MAPbI<jats:sub>3</jats:sub>s undergo drastic changes in optical properties at moderate field strengths with an ultrafast response time, via transient Wannier Stark localization. The distinct band structure of this material - the large lattice periodicity, the narrow electronic energy bandwidths, and the coincidence of these two along the same high-symmetry direction – enables relatively weak fields to bring this material into the Wannier Stark regime. Its polycrystalline nature is not detrimental to the optical switching performance of the material, since the least dispersive direction of the band structure dominates the contribution to the optical response, which favors low-cost fabrication. Together with the outstanding photophysical properties of MAPbI<jats:sub>3</jats:sub>, this finding highlights the great potential of this material in ultrafast light modulation and novel photonic applications.</jats:p>}},
  author       = {{Berghoff, Daniel and Bühler, Johannes and Bonn, Mischa and Leitenstorfer, Alfred and Meier, Torsten and Kim, Heejae}},
  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        = {{{Low-field onset of Wannier-Stark localization in a polycrystalline hybrid organic inorganic perovskite}}},
  doi          = {{10.1038/s41467-021-26021-4}},
  volume       = {{12}},
  year         = {{2021}},
}

@article{23477,
  author       = {{Thong, Le Huu and Ngo, Cong and Duc, Huynh Thanh and Song, Xiaohong and Meier, Torsten}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  pages        = {{085201}},
  title        = {{{Microscopic analysis of high harmonic generation in semiconductors with degenerate bands}}},
  doi          = {{10.1103/physrevb.103.085201}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{21946,
  abstract     = {{Lithium niobate (LiNbO3), a material frequently used in optical applications, hosts different kinds of polarons that significantly affect many of its physical properties. In this study, a variety of electron polarons, namely free, bound, and bipolarons, are analyzed using first-principles calculations. We perform a full structural optimization based on density-functional theory for selected intrinsic defects with special attention to the role of symmetry-breaking distortions that lower the total energy. The cations hosting the various polarons relax to a different degree, with a larger relaxation corresponding to a larger gap between the defect level and the conduction-band edge. The projected density of states reveals that the polaron states are formerly empty Nb 4d states lowered into the band gap. Optical absorption spectra are derived within the independent-particle approximation, corrected by the GW approximation that yields a wider band gap and by including excitonic effects within the Bethe-Salpeter equation. Comparing the calculated spectra with the density of states, we find that the defect peak observed in the optical absorption stems from transitions between the defect level and a continuum of empty Nb 4d states. Signatures of polarons are further analyzed in the reflectivity and other experimentally measurable optical coefficients.}},
  author       = {{Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}},
  issn         = {{2073-4352}},
  journal      = {{Crystals}},
  pages        = {{542}},
  publisher    = {{MDPI}},
  title        = {{{Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}}},
  doi          = {{10.3390/cryst11050542}},
  volume       = {{11}},
  year         = {{2021}},
}

@inproceedings{43746,
  abstract     = {{Population/mixing-time-dependent two-dimensional coherent spectra are presented for exciton-polaritons in a microcavity. Theory based on dynamically-controlled truncation reveals coherent and incoherent contributions to the decay dynamics.}},
  author       = {{Meier, Torsten and Paul, Jagannath and Rose, Hendrik and Wahlstrand, Jared K and Bristow, Alan D}},
  booktitle    = {{Frontiers in Optics}},
  isbn         = {{978-1-55752-308-2}},
  location     = {{Washington, DC United States}},
  publisher    = {{Frontiers in Optics}},
  title        = {{{Coherent and incoherent contribution of population dynamics of semiconductor exciton-polaritons}}},
  doi          = {{10.1364/FIO.2021.FW5C.6}},
  year         = {{2021}},
}

@inproceedings{23474,
  author       = {{Reichelt, Matthias and Rose, Hendrik and Kosarev, Alexander N. and Poltavtsev, Sergey V. and Bayer, Manfred and Akimov, Ilya A. and Schneider, Christian and Kamp, Martin and Höfling, Sven and Meier, Torsten}},
  booktitle    = {{Ultrafast Phenomena and Nanophotonics XXV}},
  editor       = {{Betz, Markus and Elezzabi, Abdulhakem Y.}},
  title        = {{{Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles}}},
  doi          = {{10.1117/12.2576887}},
  volume       = {{11684}},
  year         = {{2021}},
}

@article{23478,
  author       = {{Rose, Hendrik and Popolitova, D. V. and Tikhonova, O. V. and Meier, Torsten and Sharapova, Polina}},
  issn         = {{2469-9926}},
  journal      = {{Physical Review A}},
  title        = {{{Dark-state and loss-induced phenomena in the quantum-optical regime of Λ-type three-level systems}}},
  doi          = {{10.1103/physreva.103.013702}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{23473,
  author       = {{Belobo, Didier Belobo and Meier, Torsten}},
  issn         = {{1367-2630}},
  journal      = {{New Journal of Physics}},
  title        = {{{Approximate nonlinear wave solutions of the coupled two-component Gross–Pitaevskii equations with spin–orbit interaction}}},
  doi          = {{10.1088/1367-2630/abf3ed}},
  volume       = {{23}},
  year         = {{2021}},
}

@article{22881,
  author       = {{Nguyen, T. T. Nhung and Sollfrank, T. and Tegenkamp, C. and Rauls, E. and Gerstmann, Uwe}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  pages        = {{L201408}},
  title        = {{{Impact of screening and relaxation on weakly coupled two-dimensional heterostructures}}},
  doi          = {{10.1103/physrevb.103.l201408}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{22310,
  author       = {{Neufeld, Sergej and Bocchini, Adriana and Schmidt, Wolf Gero}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  title        = {{{Potassium titanyl phosphate Z- and Y-cut surfaces from density-functional theory}}},
  doi          = {{10.1103/physrevmaterials.5.064407}},
  year         = {{2021}},
}

@article{22008,
  author       = {{Plaickner, Julian and Speiser, Eugen and Braun, Christian and Schmidt, Wolf Gero and Esser, Norbert and Sanna, Simone}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  title        = {{{Surface localized phonon modes at the Si(553)-Au nanowire system}}},
  doi          = {{10.1103/physrevb.103.115441}},
  year         = {{2021}},
}

@article{40244,
  author       = {{Meier, Lukas and Schmidt, Wolf Gero}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}},
  number       = {{1}},
  publisher    = {{Wiley}},
  title        = {{{GaInP/AlInP(001) Interfaces from Density Functional Theory}}},
  doi          = {{10.1002/pssb.202100462}},
  volume       = {{259}},
  year         = {{2021}},
}

@article{22009,
  author       = {{Ruiz Alvarado, Isaac Azahel and Karmo, Marsel and Runge, Erich and Schmidt, Wolf Gero}},
  issn         = {{2470-1343}},
  journal      = {{ACS Omega}},
  pages        = {{6297--6304}},
  title        = {{{InP and AlInP(001)(2 × 4) Surface Oxidation from Density Functional Theory}}},
  doi          = {{10.1021/acsomega.0c06019}},
  year         = {{2021}},
}

@article{22960,
  abstract     = {{We perform a theoretical analysis of the structural and electronic properties of sodium potassium niobate K1-xNaxNbO3 in the orthorhombic room-temperature phase, based on density-functional theory in combination with the supercell approach. Our results for x=0 and x=0.5 are in very good agreement with experimental measurements and establish that the lattice parameters decrease linearly with increasing Na contents, disproving earlier theoretical studies based on the virtual-crystal approximation that claimed a highly nonlinear behavior with a significant structural distortion and volume reduction in K0.5Na0.5NbO3 compared to both end members of the solid solution. Furthermore, we find that the electronic band gap varies very little between x=0 and x=0.5, reflecting the small changes in the lattice parameters.}},
  author       = {{Bidaraguppe Ramesh, Nithin and Schmidt, Falko and Schindlmayr, Arno}},
  issn         = {{1434-6036}},
  journal      = {{The European Physical Journal B}},
  number       = {{8}},
  publisher    = {{EDP Sciences, Società Italiana di Fisica and Springer}},
  title        = {{{Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory}}},
  doi          = {{10.1140/epjb/s10051-021-00179-8}},
  volume       = {{94}},
  year         = {{2021}},
}

@article{22761,
  author       = {{Friedrich, Christoph and Blügel, Stefan and Schindlmayr, Arno}},
  issn         = {{2469-9969}},
  journal      = {{Physical Review B}},
  number       = {{3}},
  publisher    = {{American Physical Society}},
  title        = {{{Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]}}},
  doi          = {{10.1103/PhysRevB.104.039901}},
  volume       = {{104}},
  year         = {{2021}},
}

@article{37334,
  abstract     = {{<jats:p>Uniaxial anisotropy in nonlinear birefringent crystals limits the efficiency of nonlinear optical interactions and breaks the spatial symmetry of light generated in the parametric down-conversion (PDC) process. Therefore, this effect is usually undesirable and must be compensated for. However, high gain may be used to overcome the destructive role of anisotropy in order to generate bright two-mode correlated twin-beams. In this work, we provide a rigorous theoretical description of the spatial properties of bright squeezed light in the presence of strong anisotropy. We investigate a single crystal and a system of two crystals with an air gap (corresponding to a nonlinear SU(1,1) interferometer) and demonstrate the generation of bright correlated twin-beams in such configurations at high gain due to anisotropy. We explore the mode structure of the generated light and show how anisotropy, together with crystal spacing, can be used for radiation shaping.</jats:p>}},
  author       = {{Riabinin, M. and Sharapova, Polina and Meier, Torsten}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{Atomic and Molecular Physics, and Optics}},
  number       = {{14}},
  pages        = {{21876--21890}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Bright correlated twin-beam generation and radiation shaping in high-gain parametric down-conversion with anisotropy}}},
  doi          = {{10.1364/oe.424977}},
  volume       = {{29}},
  year         = {{2021}},
}

@article{26287,
  author       = {{Geraldi, Andrea and De, Syamsundar and Laneve, Alessandro and Barkhofen, Sonja and Sperling, Jan and Mataloni, Paolo and Silberhorn, Christine}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  title        = {{{Transient subdiffusion via disordered quantum walks}}},
  doi          = {{10.1103/physrevresearch.3.023052}},
  year         = {{2021}},
}

@article{21021,
  author       = {{Tiedau, J. and Engelkemeier, M. and Brecht, Benjamin and Sperling, Jan and Silberhorn, Christine}},
  issn         = {{0031-9007}},
  journal      = {{Physical Review Letters}},
  title        = {{{Statistical Benchmarking of Scalable Photonic Quantum Systems}}},
  doi          = {{10.1103/physrevlett.126.023601}},
  volume       = {{126}},
  year         = {{2021}},
}

@article{26286,
  author       = {{Prasannan, Nidhin and De, Syamsundar and Barkhofen, Sonja and Brecht, Benjamin and Silberhorn, Christine and Sperling, Jan}},
  issn         = {{2469-9926}},
  journal      = {{Physical Review A}},
  title        = {{{Experimental entanglement characterization of two-rebit states}}},
  doi          = {{10.1103/physreva.103.l040402}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{26285,
  author       = {{Köhnke, S. and Agudelo, E. and Schünemann, M. and Schlettwein, O. and Vogel, W. and Sperling, Jan and Hage, B.}},
  issn         = {{0031-9007}},
  journal      = {{Physical Review Letters}},
  title        = {{{Quantum Correlations beyond Entanglement and Discord}}},
  doi          = {{10.1103/physrevlett.126.170404}},
  year         = {{2021}},
}

@article{23816,
  abstract     = {{Employing the ultrafast control of electronic states of a semiconductor quantum dot in a cavity, we introduce an approach to achieve on-demand emission of single photons with almost perfect indistinguishability and photon pairs with near ideal entanglement. Our scheme is based on optical excitation off resonant to a cavity mode followed by ultrafast control of the electronic states using the time-dependent quantum-confined Stark effect, which then allows for cavity-resonant emission. Our theoretical analysis considers cavity-loss mechanisms, the Stark effect, and phonon-induced dephasing, allowing realistic predictions for finite temperatures.}},
  author       = {{Bauch, David and Heinze, Dirk Florian and Förstner, Jens and Jöns, Klaus and Schumacher, Stefan}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  keywords     = {{tet_topic_qd}},
  pages        = {{085308}},
  title        = {{{Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots}}},
  doi          = {{10.1103/physrevb.104.085308}},
  volume       = {{104}},
  year         = {{2021}},
}