Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 57: Open Quantum Systems III

Q 57.6: Vortrag

Donnerstag, 5. März 2026, 15:45–16:00, P 4

Perturbative and non-perturbative continuous similarity transformations for Lindbladians — •Lea Lenke and Kai Phillip Schmidt — FAU Erlangen-Nürnberg

We study the Lindbladian of the dissipative transverse field Ising chain by continuous similarity transformations (CSTs). The latter are the two flow equation methods pcst⁺⁺ and directly evaluated enhanced perturbative continuous unitary transformations (deepCUTs) which both generate effective block-diagonal operators. The first method, pcst⁺⁺, is a generalization of the method of perturbative continuous unitary transformations (pCUTs) to non-Hermitian operators like the Lindbladian and multiple quasiparticle types. The second method, deepCUT, uses a perturbative truncation scheme to generate a non-perturbative expansion of the effective operator. We apply the same generator as in the definition of the pcst⁺⁺ to generalize deepCUT to non-Hermitian operators. We apply both methods 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.