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“Non-Hermitian Topological Physics”
Thursday, 24 Nov. 2022
Video-Recording for any system with MP4-support
- Video.mp4 (ca. 453 Mb)
15:15 – 16:30
Hermiticity is a fundamental aspect of isolated quantum systems. Nevertheless,
non-Hermitian effects are ubiquitous in both classical and quantum systems.
In the classical realm this is manifested e.g. as friction in mechanical systems,
resistivity in electrical circuits, and losses in optics. In the quantum realm
it reflects the dynamics of open systems, as well as decay, scattering, resonances
and broadening due to e.g. interactions and disorder. During the past few decades
notions of topology have revolutionised the understanding of matter as recognized
by several Nobel prizes. This understanding is however based on the topology
and stability of Hermitian matrices. In contrast, in the past few years, intense
theoretical and experimental research has revealed that non-Hermitian effects
dramatically enrich the phenomenology of topological physics—providing a
cross-disciplinary frontier that is rapidly expanding . Using simple examples,
I will describe the essence of these developments starting with the non-Hermitian
concept of exceptional degeneracies at which both eigenvalues and eigenvectors
coalesce. I will also discuss how the bulk-boundary correspondence is radically
modified in non-Hermitian systems and how this might be harnessed in novel
sensor devices .
 E.J. Bergholtz, J.C. Budich, and F.K. Kunst, Reviews of Modern Physics 93, 15005 (2021).
 J.C. Budich and E.J. Bergholtz, Physical Review Letters 125, 180403 (2020).
Emil Bergholtz is the recipient of Göran Gustafsson Prize (KVA)
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