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Abstract |
Chiral edge states are unidirectional modes that propagate along the boundaries
of two-dimensional insulators when time-reversal symmetry is broken. Their
existence can be understood from topological arguments, as their number is given
by a topological index of the bulk bands, the Chern number. Periodically driven
quantum systems (also dubbed Floquet systems), whose evolution are dictated by a
unitary operator, were surprizingly found to exhibit chiral edge states that are
not always predicted by the Chern numbers. Those anomalous chiral modes have
however also a topological origin, but with no counterpart in Hamiltonian
(static) systems.
In this talk, I will show that anomalous edge modes are actually very natural in
scattering networks, and discuss why one can expect them beyond the realm of
periodic driven systems. Then, I will discuss recent numerical and experimental
results with microwave networks that reveal a superior robustness of edge-
mediated transport in the anomalous phase than in the Chern phase. |
