Rostock 2019 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 8: Quantum Optics and Photonics I

Q 8.3: Talk

Monday, March 11, 2019, 11:00–11:15, S Ex 04 E-Tech

Switching Light at Interfaces between Anomalous Floquet Topological Insulators — •Francesco Piccioli, Lukas Maczewsky, Mark Kremer, Matthias Heinrich, and Alexander Szameit — Institut für Physik, Universitat Rostock, Albert-Einstein-Str. 23, 18059 Rostock, Germany

Anomalous Floquet Topological Insulators (A-FTIs) are time-driven systems in which topological edge modes arise across a bandgap with non-vanishing Winding number. Our theoretical proposal outlines an A-FTI based on the honeycomb geometry with two different bandgaps and topological edge modes across both of them. We study the interface between two mutually detuned incarnations of such systems. The detuning results in a relative shift of the respective band-structures that, due to the periodicity in time, effectively exchanges the position of the two bandgaps. Since both sub-systems are characterized by a unitary winding number, their interface is not expected to support topological states. Indeed, tight binding simulations merely reveal states with quasi-flat dispersion that are not connected to any bulk band and therefore do not appear to be of topological nature. Rather, they can be intuitively understood to stem from the interplay between counter-propagating topological modes existing at the inside edges of the two sub-systems. However, we show how a topological edge mode can be forced to interact with these states, and demonstrate the suppression of the interfacial state for certain values of the modes wave vector. In this vein, our proposed system may serve as switch for the interface state via the topological mode wave vector.