@inproceedings{45758,
  author       = {{Bauer, Anna Brigitte and Reinhold, Peter}},
  booktitle    = {{Lernen, Lehren und Forschen in einer digital geprägten Welt}},
  editor       = {{van Vorst, Helena}},
  location     = {{Aachen 2022}},
  title        = {{{PSФ: Entwicklung einer abgestimmten Studieneingangsphase (Physik) }}},
  year         = {{2023}},
}

@article{43827,
  abstract     = {{A series of new organic donor–π–acceptor dyes incorporating a diquat moiety as a novel electron-acceptor unit have been synthesized and characterized. The analytical data were supported by DFT calculations. These dyes were explored in the aerobic thiocyanation of indoles and pyrroles. Here they showed a high photocatalytic activity under visible light, giving isolated yields of up to 97 %. In addition, the photocatalytic activity of standalone diquat and methyl viologen through formation of an electron donor acceptor complex is presented.}},
  author       = {{Meier, Armin and Badalov, Sabuhi and Biktagirov, Timur and Schmidt, Wolf Gero and Wilhelm, René}},
  issn         = {{0947-6539}},
  journal      = {{Chemistry – A European Journal}},
  keywords     = {{General Chemistry, Catalysis, Organic Chemistry}},
  number       = {{22}},
  pages        = {{ e202203541}},
  publisher    = {{Wiley}},
  title        = {{{Diquat Based Dyes: A New Class of Photoredox Catalysts and Their Use in Aerobic Thiocyanation}}},
  doi          = {{10.1002/chem.202203541}},
  volume       = {{ 29}},
  year         = {{2023}},
}

@article{45868,
  abstract     = {{Perfect vector vortex beams (PVVBs) have attracted considerable interest due to their peculiar optical features. PVVBs are typically generated through the superposition of perfect vortex beams, which suffer from the limited number of topological charges (TCs). Furthermore, dynamic control of PVVBs is desirable and has not been reported. We propose and experimentally demonstrate hybrid grafted perfect vector vortex beams (GPVVBs) and their dynamic control. Hybrid GPVVBs are generated through the superposition of grafted perfect vortex beams with a multifunctional metasurface. The generated hybrid GPVVBs possess spatially variant rates of polarization change due to the involvement of more TCs. Each hybrid GPVVB includes different GPVVBs in the same beam, adding more design flexibility. Moreover, these beams are dynamically controlled with a rotating half waveplate. The generated dynamic GPVVBs may find applications in the fields where dynamic control is in high demand, including optical encryption, dense data communication, and multiple particle manipulation.}},
  author       = {{Ahmed, Hammad and Ansari, Muhammad Afnan and Li, Yan and Zentgraf, Thomas and Mehmood, Muhammad Qasim and Chen, Xianzhong}},
  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        = {{{Dynamic control of hybrid grafted perfect vector vortex beams}}},
  doi          = {{10.1038/s41467-023-39599-8}},
  volume       = {{14}},
  year         = {{2023}},
}

@article{45850,
  abstract     = {{Interference between single photons is key for many quantum optics experiments and applications in quantum technologies, such as quantum communication or computation. It is advantageous to operate the systems at telecommunication wavelengths and to integrate the setups for these applications in order to improve stability, compactness and scalability. A new promising material platform for integrated quantum optics is lithium niobate on insulator (LNOI). Here, we realise Hong-Ou-Mandel (HOM) interference between telecom photons from an engineered parametric down-conversion source in an LNOI directional coupler. The coupler has been designed and fabricated in house and provides close to perfect balanced beam splitting. We obtain a raw HOM visibility of (93.5 ± 0.7) %, limited mainly by the source performance and in good agreement with off-chip measurements. This lays the foundation for more sophisticated quantum experiments in LNOI.}},
  author       = {{Babel, Silia and Bollmers, Laura and Massaro, Marcello and Luo, Kai Hong and Stefszky, Michael and Pegoraro, Federico and Held, Philip and Herrmann, Harald and Eigner, Christof and Brecht, Benjamin and Padberg, Laura and Silberhorn, Christine}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{Atomic and Molecular Physics, and Optics}},
  number       = {{14}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler}}},
  doi          = {{10.1364/oe.484126}},
  volume       = {{31}},
  year         = {{2023}},
}

@article{46133,
  author       = {{Bopp, Frederik and Schall, Johannes and Bart, Nikolai and Vögl, Florian and Cullip, Charlotte and Sbresny, Friedrich and Boos, Katarina and Thalacker, Christopher and Lienhart, Michelle and Rodt, Sven and Reuter, Dirk and Ludwig, Arne and Wieck, Andreas D. and Reitzenstein, Stephan and Müller, Kai and Finley, Jonathan J.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{16}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Coherent driving of direct and indirect excitons in a quantum dot molecule}}},
  doi          = {{10.1103/physrevb.107.165426}},
  volume       = {{107}},
  year         = {{2023}},
}

@article{46132,
  author       = {{Littmann, Mario and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}},
  number       = {{7}},
  publisher    = {{Wiley}},
  title        = {{{Remote Epitaxy of Cubic Gallium Nitride on Graphene‐Covered 3C‐SiC Substrates by Plasma‐Assisted Molecular Beam Epitaxy}}},
  doi          = {{10.1002/pssb.202300034}},
  volume       = {{260}},
  year         = {{2023}},
}

@article{46138,
  abstract     = {{<jats:p>This work reports a fully guided setup for single-mode squeezing on integrated titanium-indiffused periodically poled nonlinear resonators. A continuous-wave laser beam is delivered and the squeezed field is collected by single-mode fibers; up to −3.17(9) dB of useful squeezing is available in fibers. To showcase the usefulness of such a fiber-coupled device, we applied the generated squeezed light in a fiber-based phase sensing experiment, showing a quantum enhancement in the signal-to-noise ratio of 0.35 dB. Moreover, our investigation of the effect of photorefraction on the cavity resonance condition suggests that it causes system instabilities at high powers.</jats:p>}},
  author       = {{Domeneguetti, Renato and Stefszky, Michael and Herrmann, Harald and Silberhorn, Christine and Andersen, Ulrik L. and Neergaard-Nielsen, Jonas S. and Gehring, Tobias}},
  issn         = {{0146-9592}},
  journal      = {{Optics Letters}},
  keywords     = {{Atomic and Molecular Physics, and Optics}},
  number       = {{11}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Fully guided and phase locked Ti:PPLN waveguide squeezing for applications in quantum sensing}}},
  doi          = {{10.1364/ol.486654}},
  volume       = {{48}},
  year         = {{2023}},
}

@article{46278,
  abstract     = {{<jats:p>Site-controlled Ga droplets on AlGaAs substrates are fabricated using area-selective deposition of Ga through apertures in a mask during molecular beam epitaxy (MBE). The Ga droplets can be crystallized into GaAs quantum dots using a crystallization step under As flux. In order to model the complex process, including the masked deposition of the droplets and a reduction of their number during a thermal annealing step, a multiscale kinetic Monte Carlo (mkMC) simulation of self-assembled Ga droplet formation on AlGaAs is expanded for area-selective deposition. The simulation has only two free model parameters: the activation energy for surface diffusion and the activation energy for thermal escape of adatoms from a droplet. Simulated droplet numbers within the opening of the aperture agree quantitatively with the experimental results down to the perfect site-control, with one droplet per aperture. However, the model parameters are different compared to those of the self-assembled droplet growth. We attribute this to the presence of the mask in close proximity to the surface, which modifies the local process temperature and the As background. This approach also explains the dependence of the model parameters on the size of the aperture.</jats:p>}},
  author       = {{Feddersen, Stefan and Zolatanosha, Viktoryia and Alshaikh, Ahmed and Reuter, Dirk and Heyn, Christian}},
  issn         = {{2079-4991}},
  journal      = {{Nanomaterials}},
  keywords     = {{General Materials Science, General Chemical Engineering}},
  number       = {{3}},
  publisher    = {{MDPI AG}},
  title        = {{{Modeling of Masked Droplet Deposition for Site-Controlled Ga Droplets}}},
  doi          = {{10.3390/nano13030466}},
  volume       = {{13}},
  year         = {{2023}},
}

@inproceedings{46485,
  abstract     = {{We present a miniaturized pulse shaping device that creates an arbitrary dispersion through the interaction of multiple metasurfaces on less than 2 mm<jats:sup>3</jats:sup> volume. For this, a metalens and a grating-metasurface between two silver mirrors are fabricated. The grating contains further phase information to achieve the device's pulse shaping functionality.}},
  author       = {{Geromel, René and Georgi, Philip and Protte, Maximilian and Bartley, Tim and Huang, Lingling and Zentgraf, Thomas}},
  booktitle    = {{CLEO: Fundamental Science 2023}},
  location     = {{San Jose, USA}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Dispersion control with integrated plasmonic metasurfaces}}},
  doi          = {{10.1364/cleo_fs.2023.fth4d.3}},
  year         = {{2023}},
}

@article{44851,
  abstract     = {{<jats:p>We present the fabrication of strain-free quantum dots in the In0.53Ga0.47As/In0.52Al0.48As-system lattice matched to InP, as future sources for single and entangled photons for long-haul fiber-based quantum communication in the optical C-band. We achieved these quantum dots by local droplet etching via InAl droplets in an In0.52Al0.48As layer and subsequent filling of the holes with In0.53Ga0.47As. Here, we present detailed investigations of the hole morphologies measured by atomic force microscopy. Statistical analysis of a set of nanoholes reveals a high degree of symmetry for nearly half of them when etched at optimized temperatures. Overgrowth with 50–150 nm In0.52Al0.48As increases their diameter and elongates the holes along the [01̄1]-direction. By systematically scanning the parameter space, we were able to fill the holes with In0.53Ga0.47As, and by capping the filled holes and performing photoluminescence measurements, we observe photoluminescence emission in the O-band up into the C-band depending on the filling height of the nanoholes.</jats:p>}},
  author       = {{Deutsch, D. and Buchholz, C. and Zolatanosha, V. and Jöns, K. D. and Reuter, D.}},
  issn         = {{2158-3226}},
  journal      = {{AIP Advances}},
  keywords     = {{General Physics and Astronomy}},
  number       = {{5}},
  publisher    = {{AIP Publishing}},
  title        = {{{Telecom C-band photon emission from (In,Ga)As quantum dots generated by filling nanoholes in In0.52Al0.48As layers}}},
  doi          = {{10.1063/5.0147281}},
  volume       = {{13}},
  year         = {{2023}},
}

@inproceedings{45371,
  author       = {{Elsner, Julia and Tenberge, Claudia and Fechner, Sabine}},
  booktitle    = {{Lernen, Lehren und Forschen in einer digital geprägten Welt}},
  editor       = {{van Vorst, Helena}},
  pages        = {{925--928}},
  title        = {{{Videoanalyse des Modellierprozesses von Grundschüler*innen}}},
  volume       = {{43}},
  year         = {{2023}},
}

@article{46741,
  author       = {{Zscherp, Mario Fabian and Jentsch, Silas Aurel and Müller, Marius Johannes and Lider, Vitalii and Becker, Celina and Chen, Limei and Littmann, Mario and Meier, Falco and Beyer, Andreas and Hofmann, Detlev Michael and As, Donat Josef and Klar, Peter Jens and Volz, Kerstin and Chatterjee, Sangam and Schörmann, Jörg}},
  issn         = {{1944-8244}},
  journal      = {{ACS Applied Materials &amp; Interfaces}},
  keywords     = {{General Materials Science}},
  number       = {{33}},
  pages        = {{39513--39522}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Overcoming the Miscibility Gap of GaN/InN in MBE Growth of Cubic In<sub><i>x</i></sub>Ga<sub>1–<i>x</i></sub>N}}},
  doi          = {{10.1021/acsami.3c06319}},
  volume       = {{15}},
  year         = {{2023}},
}

@unpublished{47532,
  abstract     = {{In planar microcavities, the transverse-electric and transverse-magnetic
(TE-TM) mode splitting of cavity photons arises due to their different
penetration into the Bragg mirrors and can result in optical spin-orbit
coupling (SOC). In this work, we find that in a liquid crystal (LC) microcavity
filled with perovskite microplates, the pronounced TE-TM splitting gives rise
to a strong SOC that leads to the spatial instability of microcavity polariton
condensates under single-shot excitation. Spatially varying hole burning and
mode competition occurs between polarization components leading to different
condensate profiles from shot to shot. The single-shot polariton condensates
become stable when the SOC vanishes as the TE and TM modes are spectrally well
separated from each other, which can be achieved by application of an electric
field to our LC microcavity with electrically tunable anisotropy. Our findings
are well reproduced and traced back to their physical origin by our detailed
numerical simulations. With the electrical manipulation our work reveals how
the shot-to-shot spatial instability of spatial polariton profiles can be
engineered in anisotropic microcavities at room temperature, which will benefit
the development of stable polariton-based optoeletronic and light-emitting
devices.}},
  author       = {{Gao, Ying and Ma, Xuekai and Zhai, Xiaokun and Xing, Chunzi and Gao, Meini and Dai, Haitao and Wu, Hao and Liu, Tong and Ren, Yuan and Wang, Xiao and Pan, Anlian and Hu, Wei and Schumacher, Stefan and Gao, Tingge}},
  booktitle    = {{arXiv:2305.01368}},
  title        = {{{Single-shot spatial instability and electric control of polariton
  condensates at room temperature}}},
  year         = {{2023}},
}

@unpublished{47533,
  abstract     = {{The control and active manipulation of spin-orbit coupling (SOC) in photonic
systems is fundamental in the development of modern spin optics and topological
photonic devices. Here, we demonstrate the control of an artificial
Rashba-Dresselhaus (RD) SOC mediated by photochemical reactions in a
microcavity filled with an organic single-crystal of photochromic phase-change
character. Splitting of the circular polarization components of the optical
modes induced by photonic RD SOC is observed experimentally in momentum space.
By applying an ultraviolet light beam, we control the spatial molecular
orientation through a photochemical reaction and with that we control the
energies of the photonic modes. This way we realize a reversible conversion of
spin-splitting of the optical modes with different energies, leading to an
optically controlled switching between circularly and linearly polarized
emission from our device. Our strategy of in situ and reversible engineering of
SOC induced by a light field provides a promising approach to actively design
and manipulate synthetic gauge fields towards future on-chip integration in
photonics and topological photonic devices.}},
  author       = {{Liang, Qian and Ma, Xuekai and Ren, Jiahuan and Long, Teng and Gu, Chunling and An, Cunbin and Fu, Hongbing and Schumacher, Stefan and Liao, Qing}},
  booktitle    = {{arXiv:2309.07652}},
  title        = {{{Photochemical reaction enabling the engineering of photonic spin-orbit
  coupling in organic-crystal optical microcavities}}},
  year         = {{2023}},
}

@unpublished{47531,
  abstract     = {{Topological states have been widely investigated in different types of
systems and lattices. In the present work, we report on topological edge states
in double-wave (DW) chains, which can be described by a generalized
Aubry-Andr\'e-Harper (AAH) model. For the specific system of a
driven-dissipative exciton polariton system we show that in such potential
chains, different types of edge states can form. For resonant optical
excitation, we further find that the optical nonlinearity leads to a
multistability of different edge states. This includes topologically protected
edge states evolved directly from individual linear eigenstates as well as
additional edge states that originate from nonlinearity-induced localization of
bulk states. Extending the system into two dimensions (2D) by stacking
horizontal DW chains in the vertical direction, we also create 2D multi-wave
lattices. In such 2D lattices multiple Su-Schrieffer-Heeger (SSH) chains appear
along the vertical direction. The combination of DW chains in the horizontal
and SSH chains in the vertical direction then results in the formation of
higher-order topological insulator corner states.}},
  author       = {{Schneider, Tobias and Gao, Wenlong and Zentgraf, Thomas and Schumacher, Stefan and Ma, Xuekai}},
  booktitle    = {{arXiv:2303.12593}},
  title        = {{{Topological edge and corner states in coupled wave lattices in nonlinear  polariton condensates}}},
  year         = {{2023}},
}

@unpublished{47529,
  abstract     = {{Exceptional points (EPs) with their intriguing spectral topology have
attracted considerable attention in a broad range of physical systems, with
potential sensing applications driving much of the present research in this
field. Here we theoretically demonstrate the realization of EPs in a system
with significant nonlinearity, a non-equilibrium exciton-polariton condensate.
With the possibility to control loss and gain and nonlinearity by optical
means, this system allows for a comprehensive analysis of the interplay of
nonlinearities (Kerr-type and saturable gain) and non-Hermiticity. Not only do
we find that EPs can be intentionally shifted in parameter space by the
saturable gain, we also observe intriguing rotations and intersections of
Riemann surfaces, and find nonlinearity-enhanced sensing capabilities. Our
results are quite general in nature and illustrate the potential of tailoring
spectral topology and related phenomena in non-Hermitian systems by
nonlinearity.}},
  author       = {{Wingenbach, Jan and Schumacher, Stefan and Ma, Xuekai}},
  booktitle    = {{arXiv:2305.04855}},
  title        = {{{Tweaking Spectral Topology and Exceptional Points by Nonlinearity in
  Non-Hermitian Polariton Systems}}},
  year         = {{2023}},
}

@inproceedings{45577,
  author       = {{Webersen, Yvonne}},
  booktitle    = {{Lernen, Lehren und Forschen in  einer digital geprägten Welt. Gesellschaft für Didaktik der Chemie und Physik Jahrestagung in Aachen 2022}},
  editor       = {{van Vorst, Helena}},
  pages        = {{750--753}},
  title        = {{{Entwicklung und Evaluation einer NdN-Unterrichtsreihe zur Unterstützung von Lernpfaden}}},
  year         = {{2023}},
}

@inbook{47543,
  author       = {{Zentgraf, Thomas and Sain, Basudeb and Zhang, Shuang}},
  booktitle    = {{Fundamentals and Applications of Nonlinear Nanophotonics}},
  editor       = {{Panoiu, Nicoae C.}},
  isbn         = {{978-0-323-90614-2}},
  publisher    = {{Elsevier}},
  title        = {{{Symmetry governed nonlinear selection rules in nanophotonics }}},
  doi          = {{10.1016/B978-0-323-90614-2.00011-0}},
  year         = {{2023}},
}

@article{40513,
  abstract     = {{Geometric-phase dielectric meta-lenses made of silicon with high numerical aperture and short focal lengths are fabricated and characterised. For circularly polarised light, the same meta-lens can act as a converging or diverging lens, depending on the handedness of the circular polarisation. This effect enables application for optical tweezers that trap or release µm-size polymer beads floating in a microfluidic channel on demand. An electrically addressable polarisation converter based on liquid crystals may be used to switch between the two states of polarisation, at which the light transmitted through the meta-lens is focused (trapping) or defocussed (releasing), respectively.}},
  author       = {{Geromel, René and Rennerich, Roman and Zentgraf, Thomas and Kitzerow, Heinz-Siegfried}},
  journal      = {{Liquid Crystals}},
  number       = {{7-10}},
  pages        = {{1193--1203}},
  publisher    = {{Taylor & Francis}},
  title        = {{{Geometric-phase metalens to be used for tunable optical tweezers in microfluidics}}},
  doi          = {{10.1080/02678292.2023.2171146}},
  volume       = {{50}},
  year         = {{2023}},
}

@article{55900,
  author       = {{Scharwald, Dennis and Meier, Torsten and Sharapova, Polina}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{4}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Phase sensitivity of spatially broadband high-gain SU(1,1) interferometers}}},
  doi          = {{10.1103/physrevresearch.5.043158}},
  volume       = {{5}},
  year         = {{2023}},
}