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SUMMARY:F. Nur Ünal (University of Cambridge & University of Birmingham)
DTSTART:20250627T130000Z
DTEND:20250627T140000Z
DTSTAMP:20260423T035823Z
UID:QTFMS/5
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QTFMS/5/">To
 pology and Obstruction in Multi-level Systems</a>\nby F. Nur Ünal (Univer
 sity of Cambridge & University of Birmingham) as part of Quantum Theories 
 of Fields\, Matter\, and Strings\n\n\nAbstract\nWhile the landscape of fre
 e-fermion topological phases has drastically been expanded in the last dec
 ades\, recently novel multi-gap topological phases have been discovered wi
 th non-Abelian braiding properties of band singularities. In systems with 
 C2T or PT symmetry\, the ability of these band nodes to annihilate pairwis
 e is path dependent\, and the sign of their charges can be changed by brai
 ding nodes in adjacent gaps. I will present non-Abelian frame charges asso
 ciated with band nodes and discuss their observable signatures. I will tal
 k about the effects of the non-Bravais lattice configuration and obstructi
 on on the multi-gap topological Euler invariant\, illustrate physical sign
 atures of these non-trivial Brillouin zone boundary conditions.\n\nPRL 133
 \, 093404 (2024)\;  Nat Comm 15\, 1144 (2024)\;  PRL 125\, 053601 (2020)\;
  Alsaiari et al\, to appear (2025)\n
LOCATION:https://researchseminars.org/talk/QTFMS/5/
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