Rostock 2019 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 53: Quantum Optics and Photonics III

Q 53.2: Vortrag

Donnerstag, 14. März 2019, 14:15–14:30, S Gr. HS Maschb.

Fermionic time-reversal symmetry in a photonic topological insulator: Experiments — •Lukas Maczewsky¹, Bastian Höckendorf², Mark Kremer², Tobias Biesenthal¹, Matthias Heinrich¹, Andreas Alvermann², Holger Fehske², and Alexander Szameit¹ — ¹Institut für Physik, Universität Rostock, Albert-Einstein-Str. 23, 18059 Rostock — ²Institut für Physik, Universität Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald

In the recent years the field of topological insulators established a new phase of matter which is marked by the hallmark feature of protected chiral edge states. In fermionic systems these states occur together with time-reversal symmetry (TRS). In contrast, bosonic systems obeying TRS are generally assumed to be fundamentally precluded from supporting topological edge states. We dispel this perception in this work and experimentally demonstrate counter-propagating chiral states at the edge of a bosonic system with TRS for the first time. The core idea of our approach is to encode the effective spin of the propagating states as a degree of freedom of the underlying waveguide lattice. The proposed protocol is implemented by using the femtosecond laser writing technique. We experimentally observe the counter-propagating edge modes by excitation of single lattice sites. Additional to that we confirm the underlying fermionic TRS of the structure by light propagation through the structure in forward and backward direction. Our findings allow fermionic features in bosonic systems, thereby opening new avenues for topological physics in photonics as well as acoustics, mechanics and even matter waves.