Regensburg 2025 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 12: Quantum Coherence and Quantum Information Systems (joint session TT/DY)

DY 12.11: Talk

Tuesday, March 18, 2025, 12:30–12:45, H31

Non-Hermitian dynamics close to exceptional points — •Aisel Shiralieva, Grigorii Starkov, and Björn Trauzettel — University of Würzburg, Würzburg, Germany

Exceptional points (EPs), which are degeneracies occurring in both open classical and quantum systems, play a crucial role across numerous areas of physics. This work examines the behavior of dissipative systems with N levels, with a particular emphasis on non-Hermitian qubits and qutrits. These systems are of interest due to recent experimental studies involving a driven non-Hermitian superconducting qubit embedded within a three-level structure, where the ground state serves as an "effective bath". Although significant progress have been made in understanding EPs, the precise connection between their occurrences in non-Hermitian Hamiltonians and in the Lindblad formalism remains unclear, especially if quantum jumps are treated as perturbations. Our results reveal how EPs in these two frameworks relate to each other and illustrate how perturbations can either lift the degeneracy or eliminate the EPs entirely in the Lindblad formalism.

Keywords: non-Hermitian dynamics; Exceptional points; Lindblad equation; non-Hermitian Hamiltonian; open quantum systems