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SUMMARY:Double JCMS: Exceptional deficiency: high-dimensional coalescing n
 on-Hermitian spaces
DTSTART:20260604T080000Z
DTEND:20260604T090000Z
DTSTAMP:20260517T004700Z
UID:indico-event-9710@indico.fysik.su.se
DESCRIPTION:Speakers: Guancong Ma (HKBU)\n\nExceptional points (EPs) are s
 pectral singularities in non-Hermitian systems\, at which individual eigen
 values and eigenvectors become identical. The successful realization of EP
 s in diverse physical systems\, such as photonics\, acoustics\, cold atoms
 \, and superconducting circuits\, has triggered tremendous interest in fun
 damental physics and inspired a vast array of novel applications. However\
 , as the term “exceptional” suggests\, EPs are usually isolated spectr
 al points. Consequently\, functionalities rooted in EPs face several inher
 ent limitations\, such as narrow bandwidth. Here\, we present a generaliza
 tion of the concept of EPs characterized by the coalescence of high-dimens
 ional eigenspaces and overlapped spectra. This condition is denoted as “
 exceptional deficiency.” When this happens\, two eigenspace of identical
  but arbitrarily large dimensions exactly align\, accompanied by the coinc
 idence of their spectra. Consequently\, the full Hilbert space is highly d
 efective by “missing” half of its span. In the meantime\, the spectrum
  is entirely composed of EPs.\nThe condition of exceptional deficiency can
  be reached in a large variety of systems. We present its realization in a
  one-dimensional double-chain lattice. Intriguingly\, the exceptional defi
 ciency is a route to go beyond the bulk-edge correspondence of non-Hermiti
 an skin effects\, which relates nontrivial point-gap topology to the exist
 ence of skin modes.\n\nhttps://indico.fysik.su.se/event/9710/
LOCATION:Albano 3: 6228 - Mega (22 seats) (Albano Building 3)
URL:https://indico.fysik.su.se/event/9710/
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