SAMOP 2021 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 11: Quantum Information (joint session QI/Q)
Q 11.2: Poster
Wednesday, September 22, 2021, 16:30–18:30, P
How Quantum Evolution with Memory is Generated in a Time-Local Way — •Konstantin Nestmann1,2, Valentin Bruch1,2, and Maarten R. Wegewijs1,2,3 — 1RWTH Aachen — 2JARA-FIT — 3Peter Grünberg Institut
Two widely used approaches to the dynamics of open quantum systems with strong dissipation and memory are the Nakajima-Zwanzig and the time-convolutionless quantum master equation. The first one uses a time-nonlocal memory kernel K, whereas the second achieves the same using a time-local generator G. Here we show that the two are connected by a simple yet general fixed-point relation: G = K[G] [1].
This result provides a deep connection between these two entirely different approaches with applications to strongly interacting open quantum systems [2]. In particular, it explicitly relates two widely used but distinct perturbative expansions [3], quantitatively connects the distinct non-perturbative Markov approximations they define, and resolves the puzzling issue how these manage to converge to exactly the same stationary state.
Furthermore, our fixed-point equation naturally leads to an iterative procedure to compute the time-local generator directly from the memory kernel producing non-Markovian approximations which are guaranteed to be accurate both at short and long times.
[1] Phys. Rev. X 11, 021041 (2021)
[2] arXiv:2104.11202
[3] arXiv:2107.08949