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Q: Fachverband Quantenoptik und Photonik

Q 19: Quantum Optics II

Q 19.1: Vortrag

Dienstag, 10. März 2020, 14:00–14:15, f342

Lindbladian approximation beyond the ultra weak coupling assumption — •Tobias Becker, Ling-Na Wu, Daniel Vorberg, and André Eckardt — Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden

Markovian master equations of Lindblad form for the description of open quantum systems have not only the advantage that they guarantee a completely positive trace preserving (CPT) evolution. They are also the starting point for efficient stochastic quantum trajectory simulations. For thermal environments, such Lindblad-type master equations are commonly derived by starting from the Redfield-equation obtained within Born-Markov approximation and by applying additionally also a rotating-wave (or secular) approximation. However, the latter requires ultra weak system-bath coupling, which is small compared to the level splitting in the system, a condition which is hard to achieve in large systems that approach a continuous spectrum in the thermodynamic limit. Here, we describe an alternative approximation to the Redfield equation, which also leads to a master equation of Lindblad form. This approximation does not require ultra weak system bath coupling, but rather sufficiently large temperatures. It, thus, works in regimes, where the secular approximation breaks down. We test our results using the example of an extended Hubbard chain coupled to two baths of different temperature.