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THU: Thursday Contributed Sessions

THU 12: Quantum Thermalization: Contributed Session to Symposium

THU 12.4: Talk

Thursday, September 11, 2025, 15:00–15:15, ZHG105

Investigation of semiclassical simulations for Heisenberg-Langevin equations at low temperatures — •Scott Daniel Linz and Jochen Gemmer — Department of Mathematics/Computer Science/Physics, University of Osnabrück, D-49076 Osnabrück, Germany

A system of spins coupled to a bath is a traditional set-up in open quantum systems. Through Heisenberg's equation the spin dynamics can be modeled by a dynamical system. Interpreting terms as noise and non-Markovian damping one can arrive at a Heisenberg-Langevin equation. These are notoriously difficult to solve due to the dimensionality of the Hilbert space. Classical generalized Langevin equations, involving non-Markovian damping and colored noise are well understood and can be treated numerically with comparative ease. Thus, a semiclassical ansatz can be made by substituting quantum expectation values with classical functions. This allows the application of standard methods developed for classical stochastic dynamical systems to tackle spin dynamics. However, this approach is uncontrolled and should be benchmarked against known quantum dynamics. In this investigation a Hamiltonian for spin dynamics is manipulated in order to receive a set-up similar to the Weisskopf-Wigner theory of spontaneous emission in order to compare the results.

Keywords: Semiclassical physics; Heisenberg-Langevin equation; Weisskopf-Wigner theory; Open quantum systems; Spin dynamics