BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Mário Silveirinha (Instituto Superior Técnico) DTSTART:20200624T100000Z DTEND:20200624T110000Z DTSTAMP:20260404T131147Z UID:QM3/6 DESCRIPTION:Title: Topological theory of non-Hermitian photonic systems\nby Mário Sil veirinha (Instituto Superior Técnico) as part of Quantum Matter meets Mat hs (IST\, Lisbon)\n\n\nAbstract\nRecently\, topological materials and topo logical effects have elicited a great interest in the photonics community [1]. While condensed-matter phenomena are traditionally described by Herm itian operators\, the same is not true in the context of macroscopic elect rodynamics where a dissipative response is the rule\, not the exception. I n this talk\, I will discuss how to determine the topological phases of di ssipative (non-Hermitian) photonic structures from first principles using a gauge-independent Green function [2\, 3]. It is shown that analogous to the Hermitian case\, the Chern number can be expressed as an integral of t he system Green function over a line parallel to the imaginary-frequency a xis. The approach introduces in a natural way the "band-gaps" of non-Hermi tian systems as the strips of the complex-frequency plane wherein the syst em Green function is analytical. I apply the developed theory to nonrecipr ocal electromagnetic continua and photonic crystals\, with lossy and or ga iny elements. Furthermore\, I discuss the validity of the bulk-edge corres pondence in the non-Hermitian case.\n\n[1] L. Lu\, J. D. Joannopoulos\, M. Soljačić\, "Topological photonics"\, Nat. Photonics\, 8\, 821\, (2014). \n\n[2] M. G. Silveirinha\, "Topological theory of non-Hermitian photonic systems"\, Phys. Rev. B\, 99\, 125155\, 2019.\n\n[3] F. R. Prudêncio\, M. G. Silveirinha\, First Principles Calculation of Topological Invariants o f non-Hermitian Photonic Crystals\, arXiv:2003.01539\n LOCATION:https://stable.researchseminars.org/talk/QM3/6/ END:VEVENT END:VCALENDAR