Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 25: Nonequilibrium Quantum Systems I (joint session TT/DY)

TT 25.9: Vortrag

Dienstag, 19. März 2024, 11:45–12:00, H 3005

Effective time-dependent temperature method for fermionic master-equations — •Lukas Litzba, Eric Kleinherbers, Nikodem Szpak, and Jürgen König — Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057 Duisburg, Germany

We consider a quantum system coupled to a fermionic environment at a fixed temperature. Using the Redfield equation with time-dependent coefficients, we analyze the reduced evolution of the system. We find that the time-dependence of these coefficients can be described by an effective time-dependent contact temperature. In this way, we obtain a method which includes non-Markovian effects and can be applied to various types of Gorini-Kossakowski-Sudarshan-Lindblad equations. With this, we discuss its application to a simple setup consisting of quantum dots which may be realized experimentally. At short times, the effective temperature appears to be much higher than the true temperature of the environment but asymptotically it settles down towards the true environment value. This behavior follows from the formation of coherences between the system and the environment for short times, which is related to a transfer of energy from the coupling term of the Hamiltonian into the system.

Keywords: open quantum-systems; Redfield equation; coherence formation; short-time dynamics; quantum dots