SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 60: Quantum Dots, Quantum Wires, Point Contacts

TT 60.6: Vortrag

Donnerstag, 30. März 2023, 18:30–18:45, HSZ 03

Asymmetric couplings of quantum dot systems to environments — •Lukas Litzba, Nikodem Szpak, Eric Kleinherbers, and Jürgen König — Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany

We study systems with a few quantum dots, represented by the Fermi-Hubbard model, coupled to several Markovian baths with different coupling strengths. On the one hand, we compare different approximations (such as Redfield equation, coherent Lindblad approximation [1]) for a Master equation in first order of the quantum dot–bath coupling for strongly interacting electrons. On the other hand, we find exact solutions for non-interacting electrons. We compare the results for different coupling strength regimes and discuss the qualitative changes in the system behavior. Thereby we observe significant effects of the coupling asymmetry on energy coherences, which is linked to local versus global coupling. We look closer at systems from two to ten dots and study the non-equilibrium dynamics based on dressed excitation energies of the system as well as the associated damping rates. In this context we find transitions from global to local coupling behavior with increasing coupling strength asymmetry.
[1] E. Kleinherbers, N. Szpak, J. König, R. Schützhold, PRB 101, 125131 (2020)