Speaker: 
Flore Kunst - MPL Erlangen

Title: 
Non-Hermitian topological phenomena

Abstract:
While topological phases of matter have predominantly been studied for isolated Hermitian systems, a recent shift has been made towards considering these phases in the context of non-Hermitian Hamiltonians revealing a dramatic enrichment of the phenomenology of topological phases resulting in a cross-disciplinary frontier that is rapidly expanding. Indeed, non-Hermiticity plays a central role in both classical and quantum systems, where in the classical realm this comes about due to, e.g., gain and loss processes in optics, whereas in non-Hermiticity describes the dynamics of open quantum systems. Non-Hermitian 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 study these features in more detail, and discuss 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. Lastly, we will explore the effect of non-Hermitian topology on the dynamics of quantum emitters coupled to a bath.

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QuCoLiMa Talks are the weekly seminar of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter). The talks are given by (external) experts, whose research falls within the scope of QuCoLiMa.

More information at www.qucolima.de/talks