@article{20586,
  author       = {{Ma, Xuekai and Kartashov, YV and Kavokin, A and Schumacher, Stefan}},
  issn         = {{0146-9592}},
  journal      = {{Optics Letters}},
  number       = {{20}},
  pages        = {{5700--5703}},
  title        = {{{Chiral condensates in a polariton hexagonal ring.}}},
  doi          = {{10.1364/ol.405400}},
  volume       = {{45}},
  year         = {{2020}},
}

@article{20581,
  author       = {{Pukrop, Matthias and Schumacher, Stefan and Ma, Xuekai}},
  journal      = {{Physical Review B}},
  number       = {{20}},
  pages        = {{205301}},
  publisher    = {{American Physical Society}},
  title        = {{{Circular polarization reversal of half-vortex cores in polariton condensates}}},
  doi          = {{10.1103/PhysRevB.101.205301}},
  volume       = {{101}},
  year         = {{2020}},
}

@article{20583,
  author       = {{Ma, Xuekai and Kartashov, Yaroslav V. and Gao, Tingge and Torner, Lluis and Schumacher, Stefan}},
  journal      = {{Physical Review B}},
  number       = {{4}},
  pages        = {{045309}},
  publisher    = {{American Physical Society}},
  title        = {{{Spiraling vortices in exciton-polariton condensates}}},
  doi          = {{10.1103/PhysRevB.102.045309}},
  volume       = {{102}},
  year         = {{2020}},
}

@article{17068,
  author       = {{Braun, Christian and Neufeld, Sergej and Gerstmann, Uwe and Sanna, S. and Plaickner, J. and Speiser, E. and Esser, N. and Schmidt, Wolf Gero}},
  issn         = {{0031-9007}},
  journal      = {{Physical Review Letters}},
  number       = {{14}},
  title        = {{{Vibration-Driven Self-Doping of Dangling-Bond Wires on Si(553)-Au Surfaces}}},
  doi          = {{10.1103/physrevlett.124.146802}},
  volume       = {{124}},
  year         = {{2020}},
}

@article{40364,
  author       = {{Sharapova, Polina R. and Frascella, G. and Riabinin, M. and Pérez, A. M. and Tikhonova, O. V. and Lemieux, S. and Boyd, R. W. and Leuchs, G. and Chekhova, M. V.}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  keywords     = {{General Engineering}},
  number       = {{1}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Properties of bright squeezed vacuum at increasing brightness}}},
  doi          = {{10.1103/physrevresearch.2.013371}},
  volume       = {{2}},
  year         = {{2020}},
}

@article{40381,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>The phenomenon of entanglement is the basis of quantum information and quantum communication processes. Entangled systems with a large number of photons are of great interest at present because they provide a platform for streaming technologies based on photonics. In this paper we present a device which operates with four-photons and based on the Hong–Ou–Mandel interference. The presented device allows to maximize the degree of spatial entanglement and generate the highly entangled four-dimensional Bell states. Furthermore, the use of the interferometer in different regimes leads to fast interference fringes in the coincidence probability with period of oscillations twice smaller than the pump wavelength. We have a good agreement between theoretical simulations and experimental results.</jats:p>}},
  author       = {{Ferreri, A and Ansari, V and Brecht, Benjamin and Silberhorn, Christine and Sharapova, Polina R.}},
  issn         = {{2058-9565}},
  journal      = {{Quantum Science and Technology}},
  keywords     = {{Electrical and Electronic Engineering, Physics and Astronomy (miscellaneous), Materials Science (miscellaneous), Atomic and Molecular Physics, and Optics}},
  number       = {{4}},
  publisher    = {{IOP Publishing}},
  title        = {{{Spatial entanglement and state engineering via four-photon Hong–Ou–Mandel interference}}},
  doi          = {{10.1088/2058-9565/abb411}},
  volume       = {{5}},
  year         = {{2020}},
}

@article{23831,
  author       = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  title        = {{{Influence of the free-electron concentration on the optical properties of zincblende GaN up to 1×1020cm−3}}},
  doi          = {{10.1103/physrevmaterials.3.104603}},
  year         = {{2019}},
}

@article{8646,
  author       = {{Deppe, M. and Gerlach, J. W. and Shvarkov, S. and Rogalla, D. and Becker, H.-W. and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  title        = {{{Germanium doping of cubic GaN grown by molecular beam epitaxy}}},
  doi          = {{10.1063/1.5066095}},
  year         = {{2019}},
}

@article{8797,
  abstract     = {{Free from phase-matching constraints, plasmonic metasurfaces have contributed significantly to the control of optical nonlinearity and enhancement of nonlinear generation efficiency by engineering subwavelength meta-atoms. However, high dissipative losses and inevitable thermal heating limit their applicability in nonlinear nanophotonics. All-dielectric metasurfaces, supporting both electric and magnetic Mie-type resonances in their nanostructures, have appeared as a promising alternative to nonlinear plasmonics. High-index dielectric nanostructures, allowing additional magnetic resonances, can induce magnetic nonlinear effects, which, along with electric nonlinearities, increase the nonlinear conversion efficiency. In addition, low dissipative losses and high damage thresholds provide an extra degree of freedom for operating at high pump intensities, resulting in a considerable enhancement of the nonlinear processes. We discuss the current state of the art in the intensely developing area of all-dielectric nonlinear nanostructures and metasurfaces, including the role of Mie modes, Fano resonances, and anapole moments for harmonic generation, wave mixing, and ultrafast optical switching. Furthermore, we review the recent progress in the nonlinear phase and wavefront control using all-dielectric metasurfaces. We discuss techniques to realize all-dielectric metasurfaces for multifunctional applications and generation of second-order nonlinear processes from complementary metal–oxide–semiconductor-compatible materials.}},
  author       = {{Sain, Basudeb and Meier, Cedrik and Zentgraf, Thomas}},
  issn         = {{2577-5421}},
  journal      = {{Advanced Photonics}},
  number       = {{2}},
  pages        = {{024002}},
  title        = {{{Nonlinear optics in all-dielectric nanoantennas and metasurfaces: a review}}},
  doi          = {{10.1117/1.ap.1.2.024002}},
  volume       = {{1}},
  year         = {{2019}},
}

@article{11953,
  abstract     = {{As flexible optical devices that can manipulate the phase and amplitude of light, metasurfaces would clearly benefit from directional optical properties. However, single layer metasurface systems consisting of two-dimensional nanoparticle arrays exhibit only a weak spatial asymmetry perpendicular to the surface and therefore have mostly symmetric transmission features. Here, we present a metasurface design principle for nonreciprocal polarization encryption of holographic images. Our approach is based on a two-layer plasmonic metasurface design that introduces a local asymmetry and generates a bidirectional functionality with full phase and amplitude control of the transmitted light. The encoded hologram is designed to appear in a particular linear cross-polarization channel, while it is disappearing in the reverse propagation direction. Hence, layered metasurface systems can feature asymmetric transmission with full phase and amplitude control and therefore expand the design freedom in nanoscale optical devices toward asymmetric information processing and security features for anticounterfeiting applications.}},
  author       = {{Frese, Daniel and Wei, Qunshuo and Wang, Yongtian and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{6}},
  pages        = {{3976--3980}},
  title        = {{{Nonreciprocal Asymmetric Polarization Encryption by Layered Plasmonic Metasurfaces}}},
  doi          = {{10.1021/acs.nanolett.9b01298}},
  volume       = {{19}},
  year         = {{2019}},
}

@article{12908,
  author       = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}},
  issn         = {{0740-3224}},
  journal      = {{Journal of the Optical Society of America B}},
  keywords     = {{tet_topic_waveguides}},
  pages        = {{2395}},
  title        = {{{Oblique quasi-lossless excitation of a thin silicon slab waveguide: a guided-wave variant of an anti-reflection coating}}},
  doi          = {{10.1364/josab.36.002395}},
  volume       = {{36}},
  year         = {{2019}},
}

@article{12930,
  author       = {{Köthemann, Ronja and Weber, Nils and Lindner, Jörg K N and Meier, Cedrik}},
  issn         = {{0268-1242}},
  journal      = {{Semiconductor Science and Technology}},
  number       = {{9}},
  title        = {{{High-precision determination of silicon nanocrystals: optical spectroscopy versus electron microscopy}}},
  doi          = {{10.1088/1361-6641/ab3536}},
  volume       = {{34}},
  year         = {{2019}},
}

@article{13965,
  author       = {{Buß, J. H. and Schupp, T. and As, Donat Josef and Hägele, D. and Rudolph, J.}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  title        = {{{Optical excitation density dependence of spin dynamics in bulk cubic GaN}}},
  doi          = {{10.1063/1.5123914}},
  year         = {{2019}},
}

@article{13966,
  author       = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  title        = {{{Influence of the free-electron concentration on the optical properties of zincblende GaN up to 1×1020cm−3}}},
  doi          = {{10.1103/physrevmaterials.3.104603}},
  year         = {{2019}},
}

@article{14544,
  author       = {{Vondran, J. and Spitzer, F. and Bayer, M. and Akimov, I. A. and Trautmann, Alexander and Reichelt, Matthias and Meier, Cedrik and Weber, N. and Meier, Torsten and André, R. and Mariette, H.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{15}},
  pages        = {{155308}},
  title        = {{{Spatially asymmetric transients of propagating exciton-polariton modes in a planar CdZnTe/CdMgTe guiding structure}}},
  doi          = {{10.1103/physrevb.100.155308}},
  volume       = {{100}},
  year         = {{2019}},
}

@article{10014,
  abstract     = {{The cubic, tetragonal, and orthorhombic phase of potassium niobate (KNbO3) are studied based on density-functional theory. Starting from the relaxed atomic geometries, we analyze the influence of self-energy corrections on the electronic band structure within the GW approximation. We find that quasiparticle shifts widen the direct (indirect) band gap by 1.21 (1.44), 1.58 (1.55), and 1.67 (1.64) eV for the cubic, tetragonal, and orthorhombic phase, respectively. By solving the Bethe-Salpeter equation, we obtain the linear dielectric function with excitonic and local-field effects, which turn out to be essential for good agreement with experimental data. From our results, we extract an exciton binding energy of 0.6, 0.5, and 0.5 eV for the cubic, tetragonal, and orthorhombic phase, respectively. Furthermore, we investigate the nonlinear second-harmonic generation (SHG) both theoretically and experimentally. The frequency-dependent second-order polarization tensor of orthorhombic KNbO3 is measured for incoming photon energies between 1.2 and 1.6 eV. In addition, calculations within the independent-(quasi)particle approximation are performed for the tetragonal and orthorhombic phase. The novel experimental data are in excellent agreement with the quasiparticle calculations and resolve persistent discrepancies between earlier experimental measurements and ab initio results reported in the literature.}},
  author       = {{Schmidt, Falko and Riefer, Arthur and Schmidt, Wolf Gero and Schindlmayr, Arno and Imlau, Mirco and Dobener, Florian and Mengel, Nils and Chatterjee, Sangam and Sanna, Simone}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  number       = {{5}},
  publisher    = {{American Physical Society}},
  title        = {{{Quasiparticle and excitonic effects in the optical response of KNbO3}}},
  doi          = {{10.1103/PhysRevMaterials.3.054401}},
  volume       = {{3}},
  year         = {{2019}},
}

@article{37288,
  abstract     = {{<jats:p>An integrated chip with quantum state generation, active polarization manipulation, and precise time control is demonstrated.</jats:p>}},
  author       = {{Luo, Kai-Hong and Brauner, Sebastian and Eigner, Christof and Sharapova, Polina and Ricken, Raimund and Meier, Torsten and Herrmann, Harald and Silberhorn, Christine}},
  issn         = {{2375-2548}},
  journal      = {{Science Advances}},
  keywords     = {{Multidisciplinary}},
  number       = {{1}},
  publisher    = {{American Association for the Advancement of Science (AAAS)}},
  title        = {{{Nonlinear integrated quantum electro-optic circuits}}},
  doi          = {{10.1126/sciadv.aat1451}},
  volume       = {{5}},
  year         = {{2019}},
}

@article{13284,
  author       = {{Hannes, Wolf-Rüdiger and Meier, Torsten}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{12}},
  title        = {{{Higher-order contributions and nonperturbative effects in the nondegenerate nonlinear optical absorption of semiconductors using a two-band model}}},
  doi          = {{10.1103/physrevb.99.125301}},
  volume       = {{99}},
  year         = {{2019}},
}

@article{13365,
  abstract     = {{The KTiOPO4 (KTP) band structure and dielectric function are calculated on various levels of theory starting from density-functional calculations. Within the independent-particle approximation an electronic transport gap of 2.97 eV is obtained that widens to about 5.23 eV when quasiparticle effects are included using the GW approximation. The optical response is shown to be strongly anisotropic due to (i) the slight asymmetry of the TiO6 octahedra in the (001) plane and (ii) their anisotropic distribution along the [001] and [100] directions. In addition, excitonic effects are very important: The solution of the Bethe–Salpeter equation indicates exciton binding energies of the order of 1.5 eV. Calculations that include both quasiparticle and excitonic effects are in good agreement with the measured reflectivity.}},
  author       = {{Neufeld, Sergej and Bocchini, Adriana and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}},
  issn         = {{2515-7639}},
  journal      = {{Journal of Physics: Materials}},
  pages        = {{045003}},
  publisher    = {{IOP Publishing}},
  title        = {{{Potassium titanyl phosphate (KTP) quasiparticle energies and optical response}}},
  doi          = {{10.1088/2515-7639/ab29ba}},
  volume       = {{2}},
  year         = {{2019}},
}

@article{22887,
  author       = {{Vondran, J. and Spitzer, F. and Bayer, M. and Akimov, I. A. and Trautmann, Alexander and Reichelt, Matthias and Meier, Cedrik and Weber, N. and Meier, Torsten and André, R. and Mariette, H.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{15}},
  pages        = {{155308}},
  title        = {{{Spatially asymmetric transients of propagating exciton-polariton modes in a planar CdZnTe/CdMgTe guiding structure}}},
  doi          = {{10.1103/physrevb.100.155308}},
  volume       = {{100}},
  year         = {{2019}},
}