Institut für Theoretische Physik

21.11.2024

Theoretische Physik

Seminar Statistical Physics

Daniele Gamba

Hyperballistic transport in dense ionized matter under external

Kontakt: Peter Sollich

28.11.2024

Theoretische Physik

Seminar Statistical Physics

Mike Chatzitoffi

Thermodynamic inference of correlations in non equilibrium collective dynamics

Kontakt: Peter Sollich

03.12.2024

Theoretische Physik

Theoretisch-physikalisches Seminar - Dienstag

Volker Meden

PT-symmetric, non-Hermitian quantum many-body theory

Parity-time-(PT-)symmetric, non-Hermitian quantum many-body systems are realized as open quantum systems with PT symmetry and compatible couplings to the environment. I review the methodology to theoretically investigate such systems. Taking a mathematical physics perspective, the corresponding Hamiltonians are studied on one hand using the formalisms of PT-symmetric and biorthogonal quantum mechanics, both of which are strongly related. In these frameworks, the notion of observables is altered compared to the standard formalism of Hermitian quantum mechanics. Furthermore, the inner product is modified by including a metric operator. On the other hand, the formalism of Hermitian quantum mechanics is employed. Considering several models ranging from a toy model to one exhibiting quantum critical behavior, I show that the standard formalism always leads to reasonable results while PT-symmetric and biorthogonal quantum mechanics produces results that cannot be reconciled with our physical intuition. The ancilla approach provides a justification for using the standard formalism independent of any specific models. I discuss that within the standard formalism useful methods of quantum many-body theory such as linear response theory and functional integrals cannot easily be extended to non-Hermitian systems. Ironically, this is straightforward within PT-symmetric and biorthogonal quantum mechanics.

Kontakt: Theoretische Physik, Prof. Dr. Fabian Heidrich-Meisner

05.12.2024

Theoretische Physik

Seminar Statistical Physics

Laya Parkavousi

Random non-reciprocal interactions

Kontakt: Peter Sollich

12.12.2024

Theoretische Physik

Seminar Statistical Physics

Jeferson Dias

tba

Kontakt: Peter Sollich

09.01.2025

Theoretische Physik

Seminar Statistical Physics

Heiko Menzler

tba

Kontakt: Peter Sollich

23.01.2025

Theoretische Physik

Seminar Statistical Physics

Martin Johnsrud

Generalized Fluctuation Dissipation Relations for Active Field Theories

Kontakt: Peter Sollich

06.02.2025

Theoretische Physik

Seminar Statistical Physics

Luca Cocconi

tba

Kontakt: Peter Sollich