@article{61245,
  author       = {{Barkhausen, Franziska and Ares Santos, Laura and Schumacher, Stefan and Sperling, Jan}},
  issn         = {{2469-9926}},
  journal      = {{Physical Review A}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Entanglement between dependent degrees of freedom: Quasiparticle correlations}}},
  doi          = {{10.1103/physreva.111.032404}},
  volume       = {{111}},
  year         = {{2025}},
}

@article{61255,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>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-André-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 horizonal and SSH chains in the vertical direction then results in the formation of higher-order topological insulator corner states. Multistable corner states emerge in the nonlinear regime.</jats:p>}},
  author       = {{Schneider, Tobias and Gao, Wenlong and Zentgraf, Thomas and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{2192-8614}},
  journal      = {{Nanophotonics}},
  number       = {{4}},
  pages        = {{509--518}},
  publisher    = {{Walter de Gruyter GmbH}},
  title        = {{{Topological edge and corner states in coupled wave lattices in nonlinear polariton condensates}}},
  doi          = {{10.1515/nanoph-2023-0556}},
  volume       = {{13}},
  year         = {{2024}},
}

@article{61257,
  abstract     = {{<jats:p>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 investigate spectral topology and EPs in systems with significant nonlinearity, exemplified by a nonequilibrium 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, but we also observe intriguing rotations and intersections of Riemann surfaces and find nonlinearity-enhanced sensing capabilities. With this, our results illustrate the potential of tailoring spectral topology and related phenomena in non-Hermitian systems by nonlinearity.</jats:p>
          <jats:sec>
            <jats:title/>
            <jats:supplementary-material>
              <jats:permissions>
                <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement>
                <jats:copyright-year>2024</jats:copyright-year>
              </jats:permissions>
            </jats:supplementary-material>
          </jats:sec>}},
  author       = {{Wingenbach, Jan and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{1}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Manipulating spectral topology and exceptional points by nonlinearity in non-Hermitian polariton systems}}},
  doi          = {{10.1103/physrevresearch.6.013148}},
  volume       = {{6}},
  year         = {{2024}},
}

@article{36416,
  author       = {{De, Jianbo and Ma, Xuekai and Yin, Fan and Ren, Jiahuan and Yao, Jiannian and Schumacher, Stefan and Liao, Qing and Fu, Hongbing and Malpuech, Guillaume and Solnyshkov, Dmitry}},
  issn         = {{0002-7863}},
  journal      = {{Journal of the American Chemical Society (JACS)}},
  keywords     = {{Colloid and Surface Chemistry, Biochemistry, General Chemistry, Catalysis}},
  number       = {{3}},
  pages        = {{1557--1563}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Room-Temperature Electrical Field-Enhanced Ultrafast Switch in Organic Microcavity Polariton Condensates}}},
  doi          = {{10.1021/jacs.2c07557}},
  volume       = {{145}},
  year         = {{2023}},
}

@article{34094,
  author       = {{Gao, Ying and Li, Yao and Ma, Xuekai and Gao, Meini and Dai, Haitao and Schumacher, Stefan and Gao, Tingge}},
  issn         = {{0003-6951}},
  journal      = {{Applied Physics Letters}},
  keywords     = {{Physics and Astronomy (miscellaneous)}},
  number       = {{20}},
  publisher    = {{AIP Publishing}},
  title        = {{{Tilting nondispersive bands in an empty microcavity}}},
  doi          = {{10.1063/5.0093908}},
  volume       = {{121}},
  year         = {{2022}},
}

@article{31937,
  author       = {{Li, Yao and Ma, Xuekai and Hatzopoulos, Zaharias and Savvidis, Pavlos G. and Schumacher, Stefan and Gao, Tingge}},
  issn         = {{2330-4022}},
  journal      = {{ACS Photonics}},
  number       = {{6}},
  pages        = {{2079--2086}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Switching Off a Microcavity Polariton Condensate near the Exceptional Point}}},
  doi          = {{10.1021/acsphotonics.2c00288}},
  volume       = {{9}},
  year         = {{2022}},
}

@article{33080,
  author       = {{Long, Teng and Ma, Xuekai and Ren, Jiahuan and Li, Feng and Liao, Qing and Schumacher, Stefan and Malpuech, Guillaume and Solnyshkov, Dmitry and Fu, Hongbing}},
  issn         = {{2198-3844}},
  journal      = {{Advanced Science}},
  keywords     = {{General Physics and Astronomy, General Engineering, Biochemistry, Genetics and Molecular Biology (miscellaneous), General Materials Science, General Chemical Engineering, Medicine (miscellaneous)}},
  number       = {{29}},
  publisher    = {{Wiley}},
  title        = {{{Helical Polariton Lasing from Topological Valleys in an Organic Crystalline Microcavity}}},
  doi          = {{10.1002/advs.202203588}},
  volume       = {{9}},
  year         = {{2022}},
}

@article{32310,
  author       = {{Li, Yao and Ma, Xuekai and Zhai, Xiaokun and Gao, Meini and Dai, Haitao and Schumacher, Stefan and Gao, Tingge}},
  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        = {{{Manipulating polariton condensates by Rashba-Dresselhaus coupling at room temperature}}},
  doi          = {{10.1038/s41467-022-31529-4}},
  volume       = {{13}},
  year         = {{2022}},
}

@article{32148,
  author       = {{Gao, Xinghui and Hu, Wei and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{0146-9592}},
  journal      = {{Optics Letters}},
  keywords     = {{Atomic and Molecular Physics, and Optics}},
  number       = {{13}},
  pages        = {{3235--3238}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Unidirectional vortex waveguides and multistable vortex pairs in polariton condensates}}},
  doi          = {{10.1364/ol.457724}},
  volume       = {{47}},
  year         = {{2022}},
}

@article{26283,
  author       = {{Lüders, Carolin and Pukrop, Matthias and Rozas, Elena and Schneider, Christian and Höfling, Sven and Sperling, Jan and Schumacher, Stefan and Aßmann, Marc}},
  issn         = {{2691-3399}},
  journal      = {{PRX Quantum}},
  title        = {{{Quantifying Quantum Coherence in Polariton Condensates}}},
  doi          = {{10.1103/prxquantum.2.030320}},
  year         = {{2021}},
}

@article{21362,
  author       = {{Xue, Yan and Chestnov, Igor and Sedov, Evgeny and Kiktenko, Evgeniy and Fedorov, Aleksey K. and Schumacher, Stefan and Ma, Xuekai and Kavokin, Alexey}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{1}},
  title        = {{{Split-ring polariton condensates as macroscopic two-level quantum systems}}},
  doi          = {{10.1103/physrevresearch.3.013099}},
  volume       = {{3}},
  year         = {{2021}},
}

@article{21359,
  author       = {{Barkhausen, Franziska and Pukrop, Matthias and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{7}},
  title        = {{{Structuring coflowing and counterflowing currents of polariton condensates in concentric ring-shaped and elliptical potentials}}},
  doi          = {{10.1103/physrevb.103.075305}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{20582,
  author       = {{Berger, Bernd and Schmidt, Daniel and Ma, Xuekai and Schumacher, Stefan and Schneider, Christian and Höfling, Sven and Assmann, Marc}},
  journal      = {{Physical Review B}},
  number       = {{24}},
  pages        = {{245309}},
  publisher    = {{American Physical Society}},
  title        = {{{Formation dynamics of exciton-polariton vortices created by nonresonant annular pumping}}},
  doi          = {{10.1103/PhysRevB.101.245309}},
  volume       = {{101}},
  year         = {{2020}},
}

@article{20580,
  author       = {{Ma, Xuekai and Berger, B and Aßmann, M and Driben, R and Meier, Torsten and Schneider, C and Höfling, S and Schumacher, Stefan}},
  issn         = {{2041-1723}},
  journal      = {{Nature Communications}},
  number       = {{1}},
  pages        = {{897}},
  title        = {{{Realization of all-optical vortex switching in exciton-polariton condensates}}},
  doi          = {{10.1038/s41467-020-14702-5}},
  volume       = {{11}},
  year         = {{2020}},
}

@article{20584,
  author       = {{Ren, J and Liao, Q and Huang, H and Li, Y and Gao, T and Ma, Xuekai and Schumacher, Stefan and Yao, J and Bai, S and Fu, H}},
  issn         = {{1530-6992}},
  journal      = {{Nano Letters}},
  number       = {{10}},
  pages        = {{7550--7557}},
  title        = {{{Efficient Bosonic Condensation of Exciton Polaritons in an H-Aggregate Organic Single-Crystal Microcavity.}}},
  doi          = {{10.1021/acs.nanolett.0c03009}},
  volume       = {{20}},
  year         = {{2020}},
}

@article{20585,
  author       = {{Ma, Xuekai and Kartashov, YV and Ferrando, A and Schumacher, Stefan}},
  issn         = {{0146-9592}},
  journal      = {{Optics Letters}},
  number       = {{19}},
  pages        = {{5311--5314}},
  title        = {{{Topological edge states of nonequilibrium polaritons in hollow honeycomb arrays.}}},
  doi          = {{10.1364/ol.405844}},
  volume       = {{45}},
  year         = {{2020}},
}

@article{20587,
  author       = {{Barkhausen, F and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{0146-9592}},
  journal      = {{Optics Letters}},
  number       = {{5}},
  pages        = {{1192--1195}},
  title        = {{{Multistable circular currents of polariton condensates trapped in ring potentials.}}},
  doi          = {{10.1364/ol.386250}},
  volume       = {{45}},
  year         = {{2020}},
}

@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}},
}