@article{21374,
  abstract     = {{<jats:p>A dark-field scanning transmission ion microscopy detector was designed for the helium ion microscope. The detection principle is based on a secondary electron conversion holder with an exchangeable aperture strip allowing its acceptance angle to be tuned from 3 to 98 mrad. The contrast mechanism and performance were investigated using freestanding nanometer-thin carbon membranes. The results demonstrate that the detector can be optimized either for most efficient signal collection or for maximum image contrast. The designed setup allows for the imaging of thin low-density materials that otherwise provide little signal or contrast and for a clear end-point detection in the fabrication of nanopores. In addition, the detector is able to determine the thickness of membranes with sub-nanometer precision by quantitatively evaluating the image signal and comparing the results with Monte Carlo simulations. The thickness determined by the dark-field transmission detector is compared to X-ray photoelectron spectroscopy and energy-filtered transmission electron microscopy measurements.</jats:p>}},
  author       = {{Emmrich, Daniel and Wolff, Annalena and Meyerbröker, Nikolaus and Lindner, Jörg and Beyer, André and Gölzhäuser, Armin}},
  issn         = {{2190-4286}},
  journal      = {{Beilstein Journal of Nanotechnology}},
  pages        = {{222--231}},
  title        = {{{Scanning transmission helium ion microscopy on carbon nanomembranes}}},
  doi          = {{10.3762/bjnano.12.18}},
  year         = {{2021}},
}

@article{21631,
  abstract     = {{<jats:p>Secret sharing is a well-established cryptographic primitive for storing highly sensitive information like encryption keys for encoded data. It describes the problem of splitting a secret into different shares, without revealing any information to its shareholders. Here, we demonstrate an all-optical solution for secret sharing based on metasurface holography. In our concept, metasurface holograms are used as spatially separable shares that carry encrypted messages in the form of holographic images. Two of these shares can be recombined by bringing them close together. Light passing through this stack of metasurfaces accumulates the phase shift of both holograms and optically reconstructs the secret with high fidelity. In addition, the hologram generated by each single metasurface can uniquely identify its shareholder. Furthermore, we demonstrate that the inherent translational alignment sensitivity between two stacked metasurface holograms can be used for spatial multiplexing, which can be further extended to realize optical rulers.</jats:p>}},
  author       = {{Georgi, Philip and Wei, Qunshuo and Sain, Basudeb and Schlickriede, Christian and Wang, Yongtian and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{2375-2548}},
  journal      = {{Science Advances}},
  number       = {{16}},
  title        = {{{Optical secret sharing with cascaded metasurface holography}}},
  doi          = {{10.1126/sciadv.abf9718}},
  volume       = {{7}},
  year         = {{2021}},
}

@article{23815,
  abstract     = {{In this paper, silicon oxynitride films (SiON) grown by plasma-enhanced chemical vapor deposition are investigated. As precursor gases silane (SiH4), nitrous oxide (N2O), nitrogen (N2) and ammonia (NH3) are used with different compositions. We find that for achieving high nitrogen content adding ammonia to the precursor mix is most efficient. Moreover, we investigate the balance between adsorption and desorption processes during film growth by investigating the film growth rate as a function of the substrate temperature. From these data we are able to determine an effective activation energy for the film growth, corresponding to the difference between adsorption and desorption energy. Finally, we have thoroughly investigated the optical properties of the films using spectroscopic ellipsometry. From these measurements, we suggest a parametrized model for the refractive index and extinction coefficient in a wide range of compositions based on a Cauchy- and a Lorentz-fit.}},
  author       = {{Aschwanden, R. and Köthemann, R. and Albert, M. and Golla, C. and Meier, Cedrik}},
  issn         = {{0040-6090}},
  journal      = {{Thin Solid Films}},
  title        = {{{Optical properties of silicon oxynitride films grown by plasma-enhanced chemical vapor deposition}}},
  doi          = {{10.1016/j.tsf.2021.138887}},
  volume       = {{736}},
  year         = {{2021}},
}

@article{20900,
  author       = {{Albert, M. and Golla, C. and Meier, Cedrik}},
  issn         = {{0022-0248}},
  journal      = {{Journal of Crystal Growth}},
  title        = {{{Optical in-situ temperature management for high-quality ZnO molecular beam epitaxy}}},
  doi          = {{10.1016/j.jcrysgro.2020.126009}},
  volume       = {{557}},
  year         = {{2021}},
}

@article{22214,
  author       = {{Mund, Johannes and Yakovlev, Dmitri R. and Sadofev, Sergey and Meier, Cedrik and Bayer, Manfred}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  title        = {{{Second harmonic generation on excitons in ZnO/(Zn,Mg)O quantum wells with built-in electric fields}}},
  doi          = {{10.1103/physrevb.103.195311}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{22215,
  abstract     = {{Topological states of light represent counterintuitive optical modes localized at boundaries of finite-size optical structures that originate from the properties of the bulk. Being defined by bulk properties, such boundary states are insensitive to certain types of perturbations, thus naturally enhancing robustness of photonic circuitries. Conventionally, the N-dimensional bulk modes correspond to (N – 1)-dimensional boundary states. The higher-order bulk-boundary correspondence relates N-dimensional bulk to boundary states with dimensionality reduced by more than 1. A special interest lies in miniaturization of such higher-order topological states to the nanoscale. Here, we realize nanoscale topological corner states in metasurfaces with C6-symmetric honeycomb lattices. We directly observe nanoscale topology-empowered edge and corner localizations of light and enhancement of light–matter interactions via a nonlinear imaging technique. Control of light at the nanoscale empowered by topology may facilitate miniaturization and on-chip integration of classical and quantum photonic devices.}},
  author       = {{Kruk, Sergey S. and Gao, Wenlong and Choi, Duk-Yong and Zentgraf, Thomas and Zhang, Shuang and Kivshar, Yuri}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{11}},
  pages        = {{4592–4597}},
  publisher    = {{ACS}},
  title        = {{{Nonlinear Imaging of Nanoscale Topological Corner States}}},
  doi          = {{10.1021/acs.nanolett.1c00449}},
  volume       = {{21}},
  year         = {{2021}},
}

@article{22450,
  abstract     = {{We realize and investigate a nonlinear metasurface taking advantage of intersubband transitions in ultranarrow GaN/AlN multi-quantum well heterostructures. Owing to huge band offsets, the structures offer resonant transitions in the telecom window around 1.55 µm. These heterostructures are functionalized with an array of plasmonic antennas featuring cross-polarized resonances at these near-infrared wavelengths and their second harmonic. This kind of nonlinear metasurface allows for substantial second-harmonic generation at normal incidence which is completely absent for an antenna array without the multi-quantum well structure underneath. While the second harmonic is originally radiated only into the plane of the quantum wells, a proper geometrical arrangement of the plasmonic elements permits the redirection of the second-harmonic light to free-space radiation, which is emitted perpendicular to the surface.}},
  author       = {{Mundry, Jan and Spreyer, Florian and Jmerik, Valentin and Ivanov, Sergey and Zentgraf, Thomas and Betz, Markus}},
  issn         = {{2159-3930}},
  journal      = {{Optical Materials Express}},
  number       = {{7}},
  publisher    = {{OSA}},
  title        = {{{Nonlinear metasurface combining telecom-range intersubband transitions in GaN/AlN quantum wells with resonant plasmonic antenna arrays}}},
  doi          = {{10.1364/ome.426236}},
  volume       = {{11}},
  year         = {{2021}},
}

@article{22533,
  author       = {{Meier, F. and Protte, M. and Baron, E. and Feneberg, M. and Goldhahn, R. and Reuter, Dirk and As, D. J.}},
  issn         = {{2158-3226}},
  journal      = {{AIP Advances}},
  title        = {{{Selective area growth of cubic gallium nitride on silicon (001) and 3C-silicon carbide (001)}}},
  doi          = {{10.1063/5.0053865}},
  year         = {{2021}},
}

@article{22723,
  author       = {{Yoon, Gwanho and Tanaka, Takuo and Zentgraf, Thomas and Rho, Junsuk}},
  issn         = {{0022-3727}},
  journal      = {{Journal of Physics D: Applied Physics}},
  title        = {{{Recent progress on metasurfaces: applications and fabrication}}},
  doi          = {{10.1088/1361-6463/ac0faa}},
  volume       = {{54}},
  year         = {{2021}},
}

@unpublished{22807,
  abstract     = {{Photonic quantum technologies [1] with applications in quantum
communication, sensing as well as quantum simulation and computing, are on the
verge of becoming commercially available. One crucial building block are
tailored nanoscale integratable quantum light sources, matching the specific
needs of use-cases. Several different approaches to realize solid-state quantum
emitters [2] with high performance [3] have been pursued. However, the
properties of the emitted single photons are always defined by the individual
quantum light source and despite numerous quantum emitter tuning
techniques [4-7], scalability is still a major challenge. Here we show an
emitter-independent method to tailor and control the properties of the single
photon emission. We demonstrate a laser-controlled down-conversion process from
an excited state of a quantum three-level system [8]. Starting from a biexciton
state, a tunable control laser field defines a virtual state in a stimulated
process. From there, spontaneous emission to the ground state leads to
optically controlled single photon emission. Based on this concept, we
demonstrate energy tuning of the single photon emission with a control laser
field. The nature of the involved quantum states furthermore provides a unique
basis for the future control of polarization and bandwidth, as predicted by
theory [9,10]. Our demonstration marks an important step towards tailored
single photon emission from a photonic quantum system based on quantum optical
principles.}},
  author       = {{Jonas, B. and Heinze, D. and Schöll, E. and Kallert, P. and Langer, T. and Krehs, S. and Widhalm, A. and Jöns, K. D. and Reuter, D. and Schumacher, S. and Zrenner, Artur}},
  booktitle    = {{arXiv:2105.12393}},
  title        = {{{Nonlinear down-conversion in a single quantum dot}}},
  year         = {{2021}},
}

@article{22003,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>The coherent electron spin dynamics of an ensemble of singly charged (In,Ga)As/GaAs quantum dots in a transverse magnetic field is driven by periodic optical excitation at 1 GHz repetition frequency. Despite the strong inhomogeneity of the electron <jats:italic>g</jats:italic> factor, the spectral spread of optical transitions, and the broad distribution of nuclear spin fluctuations, we are able to push the whole ensemble of excited spins into a single Larmor precession mode that is commensurate with the laser repetition frequency. Furthermore, we demonstrate that an optical detuning of the pump pulses from the probed optical transitions induces a directed dynamic nuclear polarization and leads to a discretization of the total magnetic field acting on the electron ensemble. Finally, we show that the highly periodic optical excitation can be used as universal tool for strongly reducing the nuclear spin fluctuations and preparation of a robust nuclear environment for subsequent manipulation of the electron spins, also at varying operation frequencies.</jats:p>}},
  author       = {{Evers, E. and Kopteva, N. E. and Yugova, I. A. and Yakovlev, D. R. and Reuter, Dirk and Wieck, A. D. and Bayer, M. and Greilich, A.}},
  issn         = {{2056-6387}},
  journal      = {{npj Quantum Information}},
  title        = {{{Suppression of nuclear spin fluctuations in an InGaAs quantum dot ensemble by GHz-pulsed optical excitation}}},
  doi          = {{10.1038/s41534-021-00395-1}},
  year         = {{2021}},
}

@article{22004,
  author       = {{Schall, Johannes and Deconinck, Marielle and Bart, Nikolai and Florian, Matthias and Helversen, Martin and Dangel, Christian and Schmidt, Ronny and Bremer, Lucas and Bopp, Frederik and Hüllen, Isabell and Gies, Christopher and Reuter, Dirk and Wieck, Andreas D. and Rodt, Sven and Finley, Jonathan J. and Jahnke, Frank and Ludwig, Arne and Reitzenstein, Stephan}},
  issn         = {{2511-9044}},
  journal      = {{Advanced Quantum Technologies}},
  title        = {{{Bright Electrically Controllable Quantum‐Dot‐Molecule Devices Fabricated by In Situ Electron‐Beam Lithography}}},
  doi          = {{10.1002/qute.202100002}},
  year         = {{2021}},
}

@article{28255,
  abstract     = {{Topological photonic crystals (TPhCs) provide robust manipulation of light with built-in immunity to fabrication tolerances and disorder. Recently, it was shown that TPhCs based on weak topology with a dislocation inherit this robustness and further host topologically protected lower-dimensional localized modes. However, TPhCs with weak topology at optical frequencies have not been demonstrated so far. Here, we use scattering-type scanning near-field optical microscopy to verify mid-bandgap zero-dimensional light localization close to 100 THz in a TPhC with nontrivial Zak phase and an edge dislocation. We show that because of the weak topology, differently extended dislocation centers induce similarly strong light localization. The experimental results are supported by full-field simulations. Along with the underlying fundamental physics, our results lay a foundation for the application of TPhCs based on weak topology in active topological nanophotonics, and nonlinear and quantum optic integrated devices because of their strong and robust light localization.}},
  author       = {{Lu, Jinlong and Wirth, Konstantin G. and Gao, Wenlong and Heßler, Andreas and Sain, Basudeb and Taubner, Thomas and Zentgraf, Thomas}},
  issn         = {{2375-2548}},
  journal      = {{Science Advances}},
  number       = {{49}},
  title        = {{{Observing 0D subwavelength-localized modes at ~100 THz protected by weak topology}}},
  doi          = {{10.1126/sciadv.abl3903}},
  volume       = {{7}},
  year         = {{2021}},
}

@article{26987,
  abstract     = {{Optical metasurfaces are perfect candidates for the phase and amplitude modulation of light, featuring an excellent basis for holographic applications. In this work, we present a dual amplitude holographic scheme based on the photon sieve principle, which is then combined with a phase hologram by utilizing the Pancharatnam–Berry phase. We demonstrate that two types of apertures, rectangular and square shapes in a gold film filled with silicon nanoantennas are sufficient to create two amplitude holograms at two different wavelengths in the visible, multiplexed with an additional phase-only hologram. The nanoantennas are tailored to adjust the spectral transmittance of the apertures, enabling the wavelength sensitivity. The phase-only hologram is implemented by utilizing the anisotropic rectangular structure. Interestingly, such three holograms have quantitative mathematical correlations with each other. Thus, the flexibility of polarization and wavelength channels can be utilized with custom-tailored features to achieve such amplitude and phase holography simultaneously without sacrificing any space-bandwidth product. The present scheme has the potential to store different pieces of information which can be displayed separately by switching the wavelength or the polarization state of the reading light beam.}},
  author       = {{Frese, Daniel and Sain, Basudeb and Zhou, Hongqiang and Wang, Yongtian and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{2192-8614}},
  journal      = {{Nanophotonics}},
  number       = {{18}},
  pages        = {{4543--4550}},
  publisher    = {{De Gruyter}},
  title        = {{{A wavelength and polarization selective photon sieve for holographic applications}}},
  doi          = {{10.1515/nanoph-2021-0440}},
  volume       = {{10}},
  year         = {{2021}},
}

@article{24955,
  author       = {{Woitkowski, David and Rochell, Leonie and Bauer, Anna}},
  issn         = {{2469-9896}},
  journal      = {{Physical Review Physics Education Research}},
  title        = {{{German university students’ views of nature of science in the introductory phase}}},
  doi          = {{10.1103/physrevphyseducres.17.010118}},
  year         = {{2021}},
}

@article{29524,
  author       = {{De, Syamsundar and Gil López, Jano and Brecht, Benjamin and Silberhorn, Christine and Sánchez-Soto, Luis L. and Hradil, Zdeněk and Řeháček, Jaroslav}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  keywords     = {{General Engineering}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Effects of coherence on temporal resolution}}},
  doi          = {{10.1103/physrevresearch.3.033082}},
  volume       = {{3}},
  year         = {{2021}},
}

@article{21020,
  author       = {{Ansari, Vahid and Brecht, Benjamin and Gil-Lopez, Jano and Donohue, John M. and Řeháček, Jaroslav and Hradil, Zdeněk and Sánchez-Soto, Luis L. and Silberhorn, Christine}},
  issn         = {{2691-3399}},
  journal      = {{PRX Quantum}},
  title        = {{{Achieving the Ultimate Quantum Timing Resolution}}},
  doi          = {{10.1103/prxquantum.2.010301}},
  volume       = {{2}},
  year         = {{2021}},
}

@article{22259,
  author       = {{Roman-Rodriguez, V and Brecht, Benjamin and Srinivasan, K and Silberhorn, Christine and Treps, N and Diamanti, E and Parigi, V}},
  issn         = {{1367-2630}},
  journal      = {{New Journal of Physics}},
  title        = {{{Continuous variable multimode quantum states via symmetric group velocity matching}}},
  doi          = {{10.1088/1367-2630/abef96}},
  volume       = {{23}},
  year         = {{2021}},
}

@article{23728,
  abstract     = {{We demonstrate the integration of amorphous tungsten silicide superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides. We show proof-of-principle detection of evanescently coupled photons of 1550 nm wavelength using bidirectional waveguide coupling for two orthogonal polarization directions. We investigate the internal detection efficiency as well as detector absorption using coupling-independent characterization measurements. Furthermore, we describe strategies to improve the yield and efficiency of these devices.}},
  author       = {{Höpker, Jan Philipp and Verma, Varun B and Protte, Maximilian and Ricken, Raimund and Quiring, Viktor and Eigner, Christof and Ebers, Lena and Hammer, Manfred and Förstner, Jens and Silberhorn, Christine and Mirin, Richard P and Woo Nam, Sae and Bartley, Tim}},
  issn         = {{2515-7647}},
  journal      = {{Journal of Physics: Photonics}},
  pages        = {{034022}},
  title        = {{{Integrated superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides}}},
  doi          = {{10.1088/2515-7647/ac105b}},
  volume       = {{3}},
  year         = {{2021}},
}

@article{34087,
  author       = {{Knust, Steffen and Ruhm, Lukas and Kuhlmann, Andreas and Meinderink, Dennis and Bürger, Julius and Lindner, Jörg and de los Arcos de Pedro, Maria Teresa and Grundmeier, Guido}},
  issn         = {{0377-0486}},
  journal      = {{Journal of Raman Spectroscopy}},
  keywords     = {{Spectroscopy, General Materials Science}},
  number       = {{7}},
  pages        = {{1237--1245}},
  publisher    = {{Wiley}},
  title        = {{{In situ backside Raman spectroscopy of zinc oxide nanorods in an atmospheric‐pressure dielectric barrier discharge plasma}}},
  doi          = {{10.1002/jrs.6123}},
  volume       = {{52}},
  year         = {{2021}},
}