Bonn 2025 – scientific programme

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QI: Fachverband Quanteninformation

QI 24: Open Quantum Systems I (joint session Q/QI)

QI 24.5: Talk

Wednesday, March 12, 2025, 15:45–16:00, HS I

Continuous similarity transformations for Lindbladians — •Lea Lenke and Kai Phillip Schmidt — FAU Erlangen-Nürnberg

The established approach of perturbative continuous unitary transformations (pCUTs) constructs effective block-diagonal quantum many-body Hamiltonians as a perturbative series. We extend the pCUT method to similarity transformations – dubbed pcst⁺⁺ – allowing for more general and non-Hermitian operators [1]. We apply the pcst⁺⁺ method to the Lindbladian describing the dissipative transverse field Ising chain. In the subsequent treatment of the obtained effective Lindbladian, we take advantage of its block-diagonal structure and perform a linked-cluster expansion obtaining results that are valid in the thermodynamic limit. In the next step, we aim at generalizing the method of directly evaluated enhanced perturbative continuous unitary transformations (deepCUTs) to non-Hermitian operators.

[1] L. Lenke, A. Schellenberger, and K. P. Schmidt, "Series expansions in closed and open quantum many-body systems with multiple quasiparticle types", Phys. Rev. A 108, 013323 (2023).