Publica
Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Topologically protected bound states in photonic paritytimesymmetric crystals
 Nature Materials 16 (2017), S.433438 ISSN: 14761122 ISSN: 14764660 

 Englisch 
 Zeitschriftenaufsatz 
 Fraunhofer IOF () 
Abstract
Parity–time (PT)symmetric crystals are a class of nonHermitian systems that allow, for example, the existence of modes with real propagation constants, for selforthogonality of propagating modes, and for unidirectional invisibility at defects. Photonic PTsymmetric systems that also support topological states could be useful for shaping and routing light waves. However, it is currently debated whether topological interface states can exist at all in PTsymmetric systems. Here, we show theoretically and demonstrate experimentally the existence of such states: states that are localized at the interface between two topologically distinct PTsymmetric photonic lattices. We find analytical closed form solutions of topological PTsymmetric interface states, and observe them through fluorescence microscopy in a passive PTsymmetric dimerized photonic lattice. Our results are relevant towards approaches to localize light on the interface between nonHermitian crystals.