Topological waves in non-reciprocal scattering networks | Prof. Romain Fleury скачать в хорошем качестве

Topological waves in non-reciprocal scattering networks | Prof. Romain Fleury

Prof. Romain Fleury EPFL Abstract: We study the topological properties of waves propagating in non-reciprocal scattering networks. Such networks, made of multiport non-reciprocal components connected by reciprocal transmission lines, can support three distinct topological phases: a trivial insulating phase, a Chern topological phase, and an extra anomalous topological phase. We will discuss, using simple graph theory arguments, the origin of the anomalous phase, and highlights its fundamental differences with the Chern phase. Using numerical studies and microwave experiments, we will demonstrate the superior robustness of anomalous edge transport over Chern edge transport, for various types of disorder, from random phase delays, to scattering and amorphous disorder. We will conclude on the potential applications of such networks in microwaves. Main paper/arXiv, related to the seminar, and other references: Zhang, Z., Delplace, P. & Fleury, R. Superior robustness of anomalous non-reciprocal topological edge states. Nature 598, 293–297 (2021). https://doi.org/10.1038/s41586-021-03... https://www.epfl.ch/labs/lwe/ The Department of Physics and Engineering of ITMO University (Saint Petersburg, Russia) hosts online weekly seminars to discuss recent scientific achievements of researchers from all over the world with a wide audience. The topics include experimental (Optical seminar) and theoretical (Theoretical seminar) aspects of nanophotonics, solid-state physics, material science, as well as design and applications of radiofrequency structures and devices (Microwave seminar). Upcoming and past events can be found at https://physics.itmo.ru/en/seminars   / physics.itmo     / physics_itmo     / physics.itmo   #TheoreticalSeminar #ITMO #новыйфизтех #scientificseminar 00:00:00 Intro 00:01:20 What is topology? 00:02:56 Topological invariants 00:04:06 Topology in physics 00:05:39 Topology of Bloch band structures 00:09:23 A simple example: non-reciprocal scattering networks with no reflection 00:11:08 Chern numbers 00:14:29 An example of two different circulators with reflection 00:16:33 Two definition of topology (Hermitian and Floquet) 00:17:50 Topological Floquet states 00:20:08 Anomalous edge states 00:22:13 Two possible implementation of anomalous phase 00:25:42 Graph theory consideration of unitary scattering networks 00:28:44 Eulerian graphs 00:31:44 Canonical example: the honeycomb network 00:38:52 Topological phase diagram of the honeycomb network 00:40:23 Practical Implementation 00:44:14 Random phase disorder 00:48:27 Experiments: 5 different disorder realizations 00:49:07 Scattering disorder 00:51:04 Last source of disorder - amorphism 00:54:52 Perspective and applications 00:55:46 Questions and discussion 01:06:30 End