  Both quantum information features and irreversible quantum evolution of the
models arising in physical systems in one-particle approximation are discussed.
It is shown that the calculation of the reduced density matrix and entanglement
analysis are considerably simplified in this case. The irreversible quantum
evolution described by Gorini--Kossakowski--Sudarshan--Lindblad equations in
the one-particle approximation could be defined by a solution of a Shroedinger
equation with a dissipative generator. It simplifies the solution of the
initial equation on the one side and gives a physical interpretation of such a
Shroedinger equation with non-Hermitian Hamiltonian on the other side.
