The Post-Decoherence Density Matrix Propagator for Quantum Brownian Motion

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dc.creatorHalliwell, Jonathan
dc.creatorZoupas, Andreas
dc.date1996-08-29
dc.date.accessioned2026-07-07T12:19:50Z
dc.date.available2026-07-07T12:19:50Z
dc.descriptionUsing the path integral representation of the density matrix propagator of quantum Brownian motion, we derive its asymptotic form for times greater than the localization time, $ (\hbar / γk T )^{\half}$, where $γ$ is the dissipation and $T$ the temperature of the thermal environment. The localization time is typically greater than the decoherence time, but much shorter than the relaxation time, $γ^{-1}$. We use this result to show that the reduced density operator rapidly evolves into a state which is approximately diagonal in a set of generalized coherent states. We thus reproduce, using a completely different method, a result we previously obtained using the quantum state diffusion picture (Phys.Rev. D52, 7294 (1995)). We also go beyond this earlier result, in that we derive an explicit expression for the weighting of each phase space localized state in the approximately diagonal density matrix, as a function of the initial state. For sufficiently long times it is equal to the Wigner function, and we confirm that the Wigner function is positive for times greater than the localization time (multiplied by a number of order 1).
dc.description17 pages, plain Tex, submitted to Physical Review D
dc.identifierhttps://arxiv.org/abs/quant-ph/9608046
dc.identifierhttp://arxiv.org/abs/quant-ph/9608046
dc.identifierPhys.Rev.D55:4697-4704,1997
dc.identifierdoi:10.1103/PhysRevD.55.4697
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/212896
dc.subjectQuantum Physics
dc.titleThe Post-Decoherence Density Matrix Propagator for Quantum Brownian Motion
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