Decoherence and Coherence Preservation in the Solutions of the GKSL Equation in the Theory of Open Quantum Systems

The properties of solutions of the Gorini–Kossakowski-Sudarshan–Lindblad (GKSL) equation for the density operator (matrix) of a system that has nondegenerate energy spectrum and weakly interacts with a reservoir are considered. Conditions for the existence of solutions for which the density matrix has off-diagonal entries (“coherences”) not tending to zero at large times are derived.