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Physics Seminar

Non-Hermitian physics: Exceptional points, symmetry and breakdown of the bulk-boundary correspondence

Speaker: Flore Kunst (Max Plank Erlangen)
Date: Wednesday 10 November 2021
Time: 15:00
Venue: Zoom

While topological phases of matter have mostly been studied for closed, Hermitian systems, a recent shift has been made towards considering these phases in the context of non-Hermitian Hamiltonians, which form a useful approach to describe dissipation. Such Hamiltonians may feature many exotic properties, which are radically different from their Hermitian counterparts, such as the generic appearance of exceptional points, a break down of the famed bulk-boundary correspondence, and the piling up of bulk states at the boundaries known as the non-Hermitian skin effect. In this talk, I will make use of two-band models to study these features in more detail, and study the appearance of exceptional points in the presence of symmetries. Additionally, I will show that even though the conventional bulk-boundary correspondence breaks down, it is possible to define a biorthogonal bulk-boundary correspondence by making use of biorthogonal quantum mechanics.

Short bio: Flore Kunst did her Master’s degree in Theoretical Physics from Utrecht University in 2015. Then she started PhD under supervision of Emil Bergholtz at the Free University in Berlin in 2015 and moved with Emil to Stockholm University in 2016 to finish her PhD in 2019. She worked as a Max Planck-Harvard Postdoc Fellow in the group of Ignacio Cirac at the Max Planck Institute of Quantum Optics in Garching, Germany from Oct 2019 till very recently (Oct 2021). Currently shie is a Junior Group Leader at the Max Planck Institute for the Science of Light in the theory division of Florian Marquardt in Erlangen, Germany. She is a First recipient of the Oseen medal awarded by the Swedish Physical Society for the best doctoral thesis in physics in 2019 in Sweden and the Female physicist of the week of the Germany Physical Society (March 2 - 8, 2020). She was awarded the Sigrid Arrhenius Scholarship by Stockholm University for the best doctoral dissertation in the exact sciences in 2019