Dresden 2020 – wissenschaftliches Programm
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TT 23.1: Vortrag
Dienstag, 17. März 2020, 09:30–09:45, HSZ 204
Exponential damping in perturbed quantum many-body systems — •Jonas Richter1, Fengping Jin2, Lars Knipschild1, Hans De Raedt3, Kristel Michielsen2, Jochen Gemmer1, and Robin Steinigeweg1 — 1University of Osnabrück, Germany — 2Forschungszentrum Jülich, Germany — 3University of Groningen, The Netherlands
Given a quantum many-body system and the expectation-value dynamics of some operator, we study how this reference dynamics is altered due to a perturbation of the system’s Hamiltonian. Based on projection operator techniques, we unveil that if the perturbation exhibits a random-matrix structure in the eigenbasis of the unperturbed Hamiltonian, then this perturbation effectively leads to an exponential damping of the original dynamics. Employing a combination of dynamical quantum typicality and numerical linked cluster expansions, we demonstrate that our theoretical findings are relevant for the dynamics of realistic quantum many-body models. Specifically, we study the decay of current autocorrelation functions in spin-1/2 ladder systems, where the rungs of the ladder are treated as a perturbation to the otherwise uncoupled legs. We find a convincing agreement between the exact dynamics and the lowest-order prediction over a wide range of interchain couplings, even if the perturbation is not weak.
 J. Richter et al., arXiv:1906.09268.