Berlin 2018 – scientific programme
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MA: Fachverband Magnetismus
MA 29: Topological Insulators I (joint session TT/MA)
MA 29.4: Talk
Wednesday, March 14, 2018, 12:30–12:45, A 053
Topological invariants for Floquet-Bloch systems with chiral, time-reversal, or particle-hole symmetry — •Bastian Höckendorf, Andreas Alvermann, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Greifswald, Germany
We introduce Z2-valued bulk invariants for symmetry-protected topological phases in 2+1 dimensional driven quantum systems.
These invariants adapt the W3-invariant, expressed as a sum over degeneracy points of the propagator,
to the respective symmetry class of the Floquet-Bloch Hamiltonian.
The bulk-boundary correspondence that holds for each invariant relates a non-zero value of the bulk invariant to
the existence of symmetry-protected topological boundary states.
To demonstrate this correspondence we apply our invariants to a chiral Harper, time-reversal Kane-Mele, and particle-hole symmetric graphene model with periodic driving,
where they successfully predict the appearance of boundary states that exist despite the trivial topological character of the Floquet bands.
Especially for particle-hole symmetry, combination of the W3 and the Z2-invariants
allows us to distinguish between weak and strong topological phases.
B. Höckendorf, A. Alvermann, and H. Fehske, J. Phys. A
50, 295301 (2017).
B. Höckendorf, A. Alvermann, and H. Fehske, preprint, arXiv:1708.07420 (2017).