Abstract: | Using a measure for the divisibility of a dynamical map,we study the non-Markovian character of a quantum evolution of a spin-S system,which is in an external field and weakly coupled to a bosonic bath with a certain temperature.The finite-temperature dynamics of the open system is obtained by the time-convolutionless master equation in the secular approximation.Besides the influence of the environmental spectral density function,the external field and low temperatures can afect the quantum non-Markovianity.It is found out that the non-Markovian feature of a dynamical map of a high-dimensional spin system is noticeable in contrast to that of a low-dimension spin system. |