SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 60: Quantum Dots, Quantum Wires, Point Contacts

TT 60.7: Vortrag

Donnerstag, 30. März 2023, 18:45–19:00, HSZ 03

Relaxation dynamics in Fermi-Hubbard systems coupled to environment — •Nikodem Szpak¹, Gernot Schaller², Ralf Schützhold^2,3, and Jürgen König¹ — ¹Theoretische Physik und CENIDE, Universität Duisburg-Essen, Lotharstr. 21, 47048 Duisburg — ²Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden — ³Institut für Theoretis- che Physik, Technische Universität Dresden, 01062 Dresden

We study a chain of quantum dots coupled to enviroment and describe it with the Fermi-Hubbard model coupled to fermionic baths. For different coupling regimes (interdot vs bath-dot) we derive separate Lindblad master equations and compare their properties. It is shown that for strong repulsive onsite (Coulomb) interactions and low bath temperatures the system quickly reaches a low-energy sector described effectively by the Heisenberg model. Within this sector the further dynamics depends strongly on the relative coupling strengths. For weak bath-dot coupling, the system relaxes globally to the unique anti-ferromagnetic ground state with zero total spin. For strong bath-dot coupling, the system increases its total spin to the maximal possible value and ends up in (degenerate) states exhibiting ferromagnetic order. We provide rigorous derivations as well as numerical examples.

[1] E. Kleinherbers, N. Szpak, J. König, and R. Schützhold, Phys. Rev. B 101, 125131 (2020)

[2] G. Schaller, F. Queisser, N. Szpak, J. König, and R. Schützhold, Phys. Rev. B 105, 115139 (2022)