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Q: Fachverband Quantenoptik und Photonik

Q 5: Quantum Optics: Open Quantum Systems

Q 5.7: Vortrag

Montag, 6. März 2023, 12:30–12:45, F342

Quantum Master Equations for finite system-bath coupling — •Tobias Becker¹, Lingna Wu¹, Alexander Schnell¹, Juzar Thingna² und André Eckardt¹ — ¹Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany — ²Department of Physics and Applied Physics, University of Massachusetts, Lowell, MA 01854, USA

For open quantum systems that are coupled to their environment an effective description for the reduced dynamics of the system is of great interest. For ultraweak coupling between system and bath Lindblad master equations yield an adequate approximation. However for finite coupling or for non-Markovian dynamics approaches beyond Lindblad are required. A good candidate is the Redfield equation, which is obtained in second order of the system bath coupling. However it is well known to violate positivity in certain parameter regimes. To overcome this problem we derive an alternative Lindbladian approximation to the Redfield equation, which is valid beyond the ultraweak coupling regime. Moreover we propose yet another quantum master equation, which corrects Redfield by drawing inspiration from the statistical mean-force Gibbs state.