Technische Physik

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    Dr. rer. nat. Sebastian Klembt
    Group Leader


    I am a group leader at the Chair for Applied Physics of the Julius-Maximilians-Universität Würzburg. Since 2018, I am pursuing my habilitation in the field of experimental physics. My research focus is to take effects of topological protection known from solid state physics (such as the Quantum Hall or Quantum spin Hall effect) and to bring them to photonic systems. In particular, we have realized the first topological insulator for hybrid light-matter particles: exciton-polaritons. This platform promises unique novel features, new many-body effects and quantum-coherent phenomena in this symbiotic light-matter system. Furthermore, we work on technological implementations of semiconductor based Topological Lasers and Exceptional Point Sensors.

    Research Interests

    Quantum Photonics, Optical Spectroscopy, Light-matter Interactions in Semiconductors, Topological Effects in Photonic Systems, Epitaxy, Technology and Design of Microcavities, Exciton-Polaritons in Lattices, Novel Semiconductor Laser Designs, Novel 2D Semiconductor Materials

    Academic Career

    Since 2018
     „Akad. Rat auf Zeit“ and Habilitation, University of Würzburg, Chair for Applied Physics

    2016 – 2018 
    Marie-Skłodowska-Curie-Action Fellowship “Topological Polaritons”

    Since 2015
    Group leader, Spectroscopy and Topological Photonics at the Chair for Applied Physics, University of Würzburg

    2013 – 2015
    Postdoctoral Researcher at Institut Néel, CNRS, Grenoble, France with Dr. M. Richard and Dr. Le Si Dang

    PhD (Dr. rer. nat. with highest honor „summa cum laude“), University of Bremen

    2006 – 2009
    Guest Student and Diploma thesis at ETH Zürich, Switzerland

    Mai 2009
    Diploma in Physics, University of Bremen


    Recent Teaching

    SS20: Lecture Phänomene der Physik, Hauptseminar Nanostrukturtechnik, Group seminar Recent Advances in Topological Photonics and Polaritonics, Lab course F-Praktikum: Optical Spectroscopy

    WS19/20: Lecture Physik für Studierende der Medizin im 1. Fachsemester, Group seminar Recent Advances in Topological Photonics and Polaritonics, Lab course F-Praktikum: Optical Spectroscopy

    SS19: Group seminar Recent Advances in Topological Photonics and Polaritonics, Lab course F-Praktikum: Optical Spectroscopy

    WS18/19: Exercise class Optik- und Quantenphysik 1, Lab course F-Praktikum: Optical Spectroscopy


    List of publications (13.02.2020):

    1. Exciton-polaritons in flatland: Controlling flatband properties in a Lieb lattice
      T. H. Harder, O. A. Egorov, J. Beierlein, P. Gagel, J. Michl, M. Emmerling, C. Schneider, U. Peschel, S. Höfling, and S. Klembt
      arXiv:2002.05405 (2020)
    1. Room temperature Organic Exciton-Polariton Condensate in a Lattice
      M. Dusel, S. Betzold, O. A. Egorov, S. Klembt, J. Ohmer, U. Fischer, S. Höfling, and C. Schneider
      arXiv:1907.05065 (2020)
    1. Coherence and Interaction in confined room-temperature polariton condensates with Frenkel excitons
      S. Betzold, M. Dusel, O. Kyriienko, C. P. Dietrich, S. Klembt, J. Ohmer, U. Fischer, I. A. Shelykh, C. Schneider, and S. Höfling
      ACS Photonics 7, 384-392 (2020).      doi.org/10.1021/acsphotonics.9b01300
    1. Nonresonant spin selection methods and polarization control in exciton-polariton condensates
      M. Klaas, O. A. Egorov, T. C. H. Liew, A. Nalitov, V. Marković, H. Suchomel, T. H. Harder, S. Betzold, E. A. Ostrovskaya, A. Kavokin, S. Klembt, S. Höfling, and C. Schneider
      Phys. Rev. B 99, 115303 (2019).                doi.org/10.1103/PhysRevB.99.115303
    1. Optical valley Hall effect for highly valley-coherent exciton-polaritons in an atomically thin semiconductor
      N. Lundt, Ł. Dusanowski, E. Sedov, P. Stepanov, M.M. Glazov, S. Klembt, M. Klaas, J. Beierlein, Ying Qin, S. Tongay, M. Richard, A.V. Kavokin, S. Höfling, and C. Schneider
      Nature Nanotechnology 14, 770–775 (2019).      doi.org/10.1038/s41565-019-0492-0
    1. Topologischer Isolator aus Licht und Materie: Festkörperphysik
      S. Klembt, T.H. Harder, and S. Höfling
      Physik in unserer Zeit 50, 11-12 (2019).  doi.org/10.1002/piuz.201970107
    1. Counter-directional polariton coupler
      M. Klaas, J. Beierlein, E. Rozas, S. Klembt, H. Suchomel, T.H. Harder, K. Winkler, M. Emmerling, H. Flayac, M.D. Martín, L. Viña, S. Höfling, C. Schneider
      Applied Physics Letters 114, 061102 (2019).        doi.org/10.1063/1.5067247
    1. Two-kind boson mixture honeycomb Hamiltonian of Bloch exciton-polaritons
      H. Pan, K. Winkler, M. Powlowski, M. Xie, A. Schade, M. Emmerling, M. Kamp, S. Klembt, C. Schneider, T. Byrnes, S. Höfling, and N. Y. Kim
      Physical Review B 99, 045302 (2019).   doi.org/10.1103/PhysRevB.99.045302
    1. Platform for Electrically Pumped Polariton Simulators and Topological Lasers
      H. Suchomel*, S. Klembt*, T. H. Harder, M. Klaas, O. A. Egorov, K. Winkler, M. Emmerling, R. Thomale, S. Höfling, C. Schneider
      Physical Review Letters 121, 257402 (2018).       doi.org/10.1103/PhysRevLett.121.257402
    1. Exciton-polariton topological insulator
      S. Klembt, T. H. Harder, O. A. Egorov, K. Winkler, R. Ge, M. A. Bandres, M. Emmerling, L. Worschech, T. C. H. Liew, M. Segev, C. Schneider, S. Höfling
      Nature 562, 552 (2018).                doi.org/10.1038/s41586-018-0601-5
    1. Observation of bosonic condensation in a hybrid monolayer MoSe2-GaAs microcavity
      M. Waldherr, N. Lundt, M. Klaas, S. Betzold, M. Wurdack, V. Baumann, E. Estrecho, A. Nalitov, E. Cherotchenko, H. Cai, E. A. Ostrovskaya, A. V. Kavokin, S. Tongay, S. Klembt, S. Höfling, C. Schneider
      Nature Communications 9, 3286 (2018).               doi.org/10.1038/s41467-018-05532-7
    1. Thermal decoherence of a nonequilibrium polariton fluid
      S. Klembt, P. Stepanov, T. Klein, A. Minguzzi, M. Richard
      Physical Review Letters 120, 035301 (2018).       doi.org/10.1103/PhysRevLett.120.035301
    1. Evolution of temporal coherence in confined exciton-polariton condensates
      M. Klaas, H. Flayac, M. Amthor, I.G. Savenko, S. Brodbeck, T. Ala-Nissila, S. Klembt,  C. Schneider, S. Höfling
      Physical Review Letters 120, 017401 (2018).       doi.org/10.1103/PhysRevLett.120.017401
    1. Observation of macroscopic valley-polarized monolayer exciton-polaritons at room temperature
      N. Lundt, S. Stoll, P. Nagler, A. Nalitov, S. Klembt, S. Betzold, J. Goddard, E. Frieling, A.V. Kavokin, C. Schüller, T. Korn, S. Höfling, C. Schneider
      Physical Review B 96, 241403 (2017).     doi.org/10.1103/PhysRevB.96.241403
    1. Polariton condensation in S- and P-flatbands in a two-dimensional Lieb lattice
      S. Klembt, T.H. Harder, O.A. Egorov, K. Winkler, H. Suchomel, J. Beierlein, M.. Emmerling, C. Schneider, S. Höfling
      Applied Physics Letters 111, 231102 (2017).        doi.org/10.1063/1.4995385
    1. Prototype of a bistable polariton field-effect transistor switch
      H. Suchomel, S. Brodbeck, T.C.H. Liew, M. Amthor, M. Klaas, S. Klembt, M. Kamp, S. Höfling, C. Schneider
      Scientific Reports 7, 5114 (2017).             doi.org/10.1038/s41598-017-05277-1
    1. Electrical and optical switching in the bistable regime of an electrically injected polariton laser
      M. Klaas, H. Sigurdsson, T.C.H. Liew, S. Klembt, M. Amthor, F. Hartmann, L. Worschech, C. Schneider, S. Höfling
      Physical Review B 96, 041301 (2017).     doi.org/10.1103/PhysRevB.96.041301
    1. Valley polarized relaxation and upconversion luminescence from Tamm-plasmon trion–polaritons with a MoSe2 monolayer
      N. Lundt, P. Nagler, A. Nalitov, S. Klembt, M. Wurdack, S. Stoll, T.H. Harder, S. Betzold, V. Baumann, A.V. Kavokin, C. Schüller, T. Korn, S. Höfling, C. Schneider
      2D Materials 4, 025096 (2017).                 doi.org/10.1088/2053-1583/aa6ef2
    1. Exciton-polariton flows in cross-dimensional junctions
      K. Winkler, H. Flayac, S. Klembt, A. Schade, D. Nevinskiy, M. Kamp, C. Schneider, S. Höfling
      Physical Review B 95, 201302 (2017).     doi.org/10.1103/PhysRevB.95.201302
    1. Tunable Bragg polaritons and nonlinear emission from a hybrid metal-unfolded ZnSe-based microcavity
      SKSU Rahman, T. Klein, J. Gutowski, S. Klembt, K. Sebald
      Scientific Reports 7, 767 (2017).                               doi.org/10.1038/s41598-017-00878-2
    1. Optical probing of the Coulomb interactions of an electrically pumped polariton condensate
      M. Klaas, S. Mandal, T.C.H. Liew, M. Amthor, S. Klembt, L. Worschech, C. Schneider, S. Höfling
      Applied Physics Letters 110, 151103 (2017).        doi.org/10.1063/1.4979836
    1. Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer
      N. Lundt, S. Klembt, E. Cherotchenko, S. Betzold, O. Iff, A. V. Nalitov, M. Klaas, C. P. Dietrich, A.V. Kavokin, S. Höfling, C. Schneider
      Nature communications 7, 13328 (2016).             doi.org/10.1038/ncomms13328
    1. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons
      SKSU Rahman, T. Klein, S. Klembt, J. Gutowski, D. Hommel, K. Sebald
      Scientific Reports 6, 34392 (2016).           doi.org/10.1038/srep34392
    1. Tamm plasmon polaritons in the visible spectral region and its optical properties in ZnSe‐based microcavities
      SKSU Rahman, K. Sebald, J. Gutowski, T. Klein, S Klembt, C. Kruse, D. Hommel
      physica status solidi (c) 13, 498 (2016).                 doi.org/10.1002/pssc.201510296
    1. Bragg polaritons in a ZnSe-based unfolded microcavity at elevated temperatures
      K. Sebald, SKSU Rahman, M. Cornelius, T. Kaya, J. Gutowski, T. Klein, A. Gust, D. Hommel, S. Klembt
      Applied Physics Letters 108, 121105 (2016).        doi.org/10.1063/1.4944717
    1. Polariton lasing in high-quality selenide-based micropillars in the strong coupling regime T. Klein, S. Klembt, E. Durupt, C. Kruse, D. Hommel, M. Richard
      Applied Physics Letters 107, 071101 (2015).        doi.org/10.1063/1.4928492
    1. Tailoring the optical properties of wide-bandgap based microcavities via metal films
      K. Sebald, SKSU Rahman, M. Cornelius, J. Gutowski, T. Klein, S. Klembt, C. Kruse, D. Hommel
      Applied Physics Letters 107, 062101 (2015).        doi.org/10.1063/1.4928604
    1. Exciton-polariton gas as a nonequilibrium coolant
      S. Klembt, E. Durupt, S. Datta, T. Klein, A. Baas, Y. Léger, C. Kruse, D. Hommel, A. Minguzzi, M. Richard
      Physical Review Letters 114, 186403 (2015).       doi.org/10.1103/PhysRevLett.114.186403
    1. High-power green and blue electron-beam pumped surface-emitting lasers using dielectric and epitaxial distributed Bragg reflectors
      T. Klein, S. Klembt, V.I. Kozlovsky, A. Zheng, M.D. Tiberi, C. Kruse
      Journal of Applied Physics 117, 113106 (2015).  doi.org/10.1016/0022-0248(92)90909-3
    1. Fabrication of ZnSe‐based microcavities for lasing in the strong coupling regime and polariton confinement
      T. Klein, S. Klembt, K Sebald, S Figge, A Gust, C Kruse, D Hommel, J. Gutowski, E. Durupt, Le Si Dang, M. Richard
      (invited article) physica status solidi (c) 11, 1267 (2014).  doi.org/10.1002/pssc.201300705
    1. II-VI-basierte Mikrokavitäten für den blau-violetten Spektralbereich: Lasing im Bereich schwacher und starker Kopplung
      S. Klembt
      mbv, Mensch-und-Buch-Verlag, Dissertationsschriften (2014)                    Link
    1. Blue lasing and strong coupling in ZnSe monolithic microcavities
      K. Sebald, M. Seyfried, S. Klembt, C. Kruse, T. Aschenbrenner, D. Hommel, S. Bley, A. Rosenauer, J. Gutowski
      physica status solidi (c) 10, 1230 (2013).               doi.org/10.1002/pssc.201200745
    1. On the structural properties of MgS-rich II–VI-based microcavities
      S. Klembt, K. Frank, G. Qian, T. Klein, A. Rosenauer, D. Hommel, C. Kruse
      Journal of Crystal Growth 378, 270 (2013).          doi.org/10.1016/j.jcrysgro.2012.12.003
    1. Strong coupling in monolithic microcavities with ZnSe quantum wells
      K Sebald, M Seyfried, S Klembt, S Bley, A Rosenauer, D Hommel, C. Kruse
      Applied Physics Letters 100, 161104 (2012).        doi.org/10.1063/1.4704188
    1. Blue monolithic II-VI-based vertical-cavity surface-emitting laser
      S. Klembt, M. Seyfried, T. Aschenbrenner, K. Sebald, J. Gutowski, D. Hommel, C. Kruse
      Applied Physics Letters 100, 121102 (2012).        doi.org/10.1063/1.3696029
    1. Optical polariton properties in ZnSe-based planar and pillar structured microcavities
      K. Sebald, A. Trichet, M. Richard, L.S. Dang, M. Seyfried, S. Klembt, C. Kruse, D. Hommel
      The European Physical Journal B 84, 381 (2011).               doi.org/10.1140/epjb/e2011-20551-9
    1. High-reflectivity II-VI-based distributed Bragg reflectors for the blue-violet spectral range
      S. Klembt, H. Dartsch, M. Anastasescu, M. Gartner, C. Kruse
      Applied Physics Letters 99, 151101 (2011).           doi.org/10.1063/1.3644955
    1. Optical properties of photonic molecules and elliptical pillars made of ZnSe-based microcavities
      K. Sebald, M. Seyfried, S. Klembt, C. Kruse
      Optics Express 19, 19422 (2011).              doi.org/10.1364/OE.19.019422
    1. Band gap bowing of binary alloys: Experimental results compared to theoretical tight-binding supercell calculations for Cd x Zn 1− x Se
      D. Mourad, G. Czycholl, C. Kruse, S. Klembt, R. Retzlaff, D. Hommel, M. Gartner, M. Anastasescu
      Physical Review B 82, 165204 (2010).     doi.org/10.1103/PhysRevB.82.165204