Exotic Wave-Matter Interactions in Metamaterials Based on Broken Symmetries | Prof. Andrea Alù

Theoretical Seminar at The Department of Physics & Engineering, ITMO | 16 Dec 2020 Timecodes are below the abstract. Prof. Andrea Alù City University of New York Title: "Exotic Wave-Matter Interactions in Metamaterials Based on Broken Symmetries" Abstract In this talk, I discuss our recent research activity in electromagnetics, nano-optics, and acoustics, showing how suitably tailored meta-atoms and arrangements of them open exciting venues to realize new phenomena and devices for light, radio-waves, and sound. I discuss venues to largely break Lorentz reciprocity and realize isolation without the need of magnetic bias, based on broken time-reversal symmetry induced by mechanical motion, spatio-temporal modulation, and/or nonlinearities. I also discuss how broken symmetries in space and space-time can open the opportunity to induce topological order in metamaterials. Another class of interesting metamaterials based on broken symmetries are parity-time symmetric metamaterials, which are asymmetric in space, but symmetric upon parity and time inversion. In the talk, I will also discuss the impact of these concepts from basic science to practical technology, from classical waves to quantum phenomena. 00:00 Intro 01:25 Start of the talk 02:14 Wave interactions in materials 03:08 Chiral molecules and optical activity 04:23 Circular dichroism of chiral molecules 05:30 Chiral Meta-molecules 06:38 Metamaterials: Beyond nature with artifical materials 07:20 Enhanced chirality detection with metamaterials 08:00 Extreme asymmetry over a meta-surface 12:20 Hyperbolic metasurfaces based on H-Bn nano-ribbons 14:23 2D materials and hybrid metamaterials 15:28 Hyperbolic metasurfaces for valleytronics 17:43 Symmetry-breaking hyperbolic metasurface 19:09 Question by Andrey Bogdanov 20:45 Enhancing, sorting and routing valley excitons 21:34 Moire physics and twistronics 22:45 Twisted hyperbolic metasurfaces 26:23 Question by Andrey Bogdanov 29:00 Question by Maxim Gorlach 31:05 alpha-MoO3 monolayers as hyperbolic surfaces 32:28 Twisted alpha-MoO3 bilayers 34:30 Experimental verification 34:50 Tracking the "photonic magic angle" 35:20 Low-loss canalization of light and nano-imaging 36:14 Topological phases of matter 38:03 Topological sound based on generalized symmetry 40:13 Higher-order topological light 40:50 Time-reversal symmetry and nonreciprocity 43:55 Faraday effect in nonlinear resonators 47:50 Floquet topological insulators for elastic waves 48:40 Optically pumped floquet topological meetasurfacer 50:50 Parity-time symmetry 52:18 PT-symmetry and exceptional points in optics 54:00 A PT-symmetric non-invasive acoustic sensor 55:52 Experimental validation 56:20 A sensor that does not cast a shadow 56:54 Planar lenses and cloaks 57:54 PT-symmetric sensors for telemetry 58:42 Exceptional point physics in a single-strand fiber 01:01:39 Question by Andrey Bogdanov 1:05:39 Broken symmetries for extreme wave interactions 1:06:30 Questions in the end 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