The stochastic one-body transport theory in non-relativistic framework is briefly reviewed, and a coherent damping mechanism arising from the coupling between the mean-field fluctuations and the single-particle motion is discussed. For small amplitude fluctuations, the coherent mechanism appears as a particle-phonon collision term in the transport equation for the average density matrix, which play a dominant role in damping of giant resonance excitations and nuclear collective motion at low energies. ©2001 American Institute of Physics.