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DTSTART:20200329T030000
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DTSTAMP:20260404T145825Z
UID:5c5c38a48b8be529151645@ist.ac.at
DTSTART:20200428T110000
DTEND:20200428T120000
DESCRIPTION:Speaker: Konstantin Bliokh\nhosted by Mikhail Lemeshko\nAbstrac
 t: More than 60 years ago it was shown that interfaces between isotropic h
 omogeneous optical media (including dielectrics\, metals\, negative-index 
 materials) can support surface electromagnetic waves\, which now play cruc
 ial roles in plasmonics\, metamaterials\, and nano-photonics. I will show 
 that such surface Maxwell waves have a topological origin explained by the
  bulk-boundary correspondence. Importantly\, the topological classificatio
 n is determined by the photon helicity operator within the Weyl-like repre
 sentation of Maxwell equations\, which is generically non-Hermitian even i
 n lossless optical media. The corresponding topological invariant\, which 
 determines the number of surface modes\, is a Z4 number (or a pair of Z2 n
 umbers) describing the winding of the complex helicity spectrum across the
  interface. I will also provide similar considerations and topological exp
 lanation of the surface acoustic wave that appears at interfaces between p
 ositive- and negative-density acoustic media. Instead of helicity\, its pr
 operties are described by the effective non-Hermitian four-momentum operat
 or within the Klein-Gordon representation of sound waves\, which provides 
 a single Z2  bulk index. Our theory provides a new twist and insights for 
 several areas of wave physics: Maxwell electromagnetism\, topological quan
 tum states\, non-Hermitian wave physics\, and metamaterials.
LOCATION:Heinzel Seminar Room / Office Bldg West (I21.EG.101)\, ISTA
ORGANIZER:cpetz@ist.ac.at
SUMMARY:Konstantin Bliokh: Topological non-Hermitian origin of surface elec
 tromagnetic and acoustic waves
URL:https://talks-calendar.ista.ac.at/events/2737
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