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TT: Fachverband Tiefe Temperaturen

TT 36: Topological Insulators

TT 36.6: Talk

Wednesday, March 29, 2023, 16:30–16:45, HSZ 103

PT-symmetric photonic topological insulator — •Alexander Fritzsche^1,2, Tobias Biesenthal², Lukas Maczewsky², Karolin Becker², Max Erhardt², Matthias Heinrich², Ronny Thomale¹, Yogesh Joglekar³, and Alexander Szameit² — ¹Fakultät für Physik und Astronomie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany — ²Institut für Physik, University of Rostock, Rostock, Germany — ³Department of Physics, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, Indiana, USA

Gain and loss are characteristic features of open or non-Hermitian systems and lead, in general, to instable, exponentially increasing and decreasing states. However, these instabilities can be avoided when parity-time (PT) symmetry is added to such arrangements. Because of its unique properties it has been tried to combine PT symmetry with the unrivalled robustness of transport in topological insulators. In this work we propose and experimentally realize a periodically driven topological insulator with two counterpropagating boundary states where gain and loss are distributed not only spatially but also temporally using photonic waveguides as the experimental platform. Here, the periodic driving allows us to circumvent the problems that have so far hindered the combination of PT symmetry and topological insulators thereby providing the missing link between these two realms.