Laboratoire de Physique Théorique

de la Matière Condensée

Pierre Delplace (ENS Lyon)

Anomalous chiral modes in 2D scattering networks

 

(Egalement par zoom https://us06web.zoom.us/j/87875346828?pwd=eEJxcFl3WnNWMWlna3ZWTzhxS095Zz09

 

Meeting ID: 878 7534 6828

Passcode: 765937)

 

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.