Rostock 2019 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 53: Quantum Optics and Photonics III
Q 53.1: Talk
Thursday, March 14, 2019, 14:00–14:15, S Gr. HS Maschb.
Fermionic time-reversal symmetry in a photonic topological insulator: Theory — •Bastian Höckendorf1, Lukas Maczewsky2, Mark Kremer2, Tobias Biesenthal2, Matthias Heinrich2, Andreas Alvermann1, Holger Fehske1, and Alexander Szameit2 — 1Institut für Physik, Universität Greifswald, Greifswald, Germany — 2Institut für Physik, Universität Rostock, Rostock, Germany
Much of the recent enthusiasm directed towards topological insulators is motivated by their hallmark feature of protected chiral edge states. In fermionic systems, these entities occur in the presence of time-reversal symmetry. In contrast, bosonic systems obeying time-reversal symmetry are generally assumed to be fundamentally precluded from supporting edge states. We challenge this belief by applying a new twist to the interpretation of Z2 topological insulators as two inverse Chern insulators which are related by time-reversal symmetry. Specifically, we adapt this concept to Floquet systems, and implement two inversely driven anomalous topological insulators on the sublattices of a face centered quadratic lattice. The resulting time-reversal symmetric driving protocol hosts counter-propagating edge states and is characterized by a Z2 invariant. The sublattices encode the spin degree of freedom of fermionic particles as an effective pseudo-spin degree of freedom, which makes implementation in bosonic systems possible. Photonic waveguide lattices are a natural platform for the experimental realization of our driving protocol, the results of which will be discussed in a related presentation by L. Maczewsky.