Bonn 2025 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 63: Poster – Quantum Information (joint session QI/Q)

Q 63.38: Poster

Thursday, March 13, 2025, 17:00–19:00, Tent

Consistent Strong-Coupling Quantum Master Equations from Dynamical Maps — •Anton Braun, André Eckardt, and Alexander Schnell — Technische Universität Berlin, Institut für Theoretische Physik

One of the most basic quantum master equations describing the interaction between a quantum system and its environment is the Redfield equation. It is, however, well known that it violates complete positivity and leads to incorrect steady states for non-weak coupling. Following up on work by Becker et al. [1], modifications to the Redfield equation are investigated that combat these issues by introducing a correction term that steers the dynamics towards the correct steady state. To this end, we study the exact solution of the Caldeira-Leggett model and show that the corresponding dynamical map can be obtained by combining Redfield theory with ideas from the formalism of periodically refreshed baths. In this way, divergence of the Redfield dynamical map for long times is cured by instead recursively evolving to a shorter time. Finally, the correction term of Ref. [1] can then be recovered from the so-obtained dynamical map. This gives a completely novel perspective on the long-standing issues of the Born-Markov approximation.

[1] Phys. Rev. Lett. 129, 200403 (2022)

Keywords: Redfield equation; periodically refreshed baths; dynamical map