2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19014The reduced dynamics of a quantum system interacting with a linear heat bath finds an exact representation in terms of a stochastic Schr{ö}dinger equation. All memory effects of the reservoir are transformed into noise correlations and mean-field friction. The classical limit of the resulting stochastic dynamics is shown to be a generalized Langevin equation, and conventional quantum state diffusion is recovered in the Born--Markov approximation. The non-Markovian exact dynamics, valid at arbitrary temperature and damping strength, is exemplified by an application to the dissipative two-state system.4 pages, 2 figures. To be published in Phys. Rev. LettStatistical MechanicsComputational PhysicsQuantum Physicstext