Systematic Perturbation Theory for Dynamical Coarse-Graining

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dc.creatorSchaller, Gernot
dc.creatorZedler, Philipp
dc.creatorBrandes, Tobias
dc.date2008-12-08
dc.date2009-02-20
dc.date.accessioned2026-07-07T12:54:40Z
dc.date.available2026-07-07T12:54:40Z
dc.descriptionWe demonstrate how the dynamical coarse-graining approach can be systematically extended to higher orders in the coupling between system and reservoir. Up to second order in the coupling constant we explicitly show that dynamical coarse-graining unconditionally preserves positivity of the density matrix -- even for bath density matrices that are not in equilibrium and also for time-dependent system Hamiltonians. By construction, the approach correctly captures the short-time dynamics, i.e., it is suitable to analyze non-Markovian effects. We compare the dynamics with the exact solution for highly non-Markovian systems and find a remarkable quality of the coarse-graining approach. The extension to higher orders is straightforward but rather tedious. The approach is especially useful for bath correlation functions of simple structure and for small system dimensions.
dc.description17 pages, 5 figures, version accepted for publication in PRA
dc.identifierhttps://arxiv.org/abs/0812.1507
dc.identifierhttp://arxiv.org/abs/0812.1507
dc.identifierPhysical Review A 79(3), 032110, (2009)
dc.identifierdoi:10.1103/PhysRevA.79.032110
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/224015
dc.subjectQuantum Physics
dc.subjectMesoscale and Nanoscale Physics
dc.titleSystematic Perturbation Theory for Dynamical Coarse-Graining
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