An alternative non-Markovianity measure by divisibility of dynamical map
  Identifying non-Markovianity with non-divisibility, we propose a measure for non-Markovinity of quantum process. Three examples are presented to illustrate the non-Markovianity, measure for non-Markovianity is calculated and discussed. Comparison with other measures of non-Markovianity is made. Our non-Markovianity measure has the merit that no optimization procedure is required and it is finite for any quantum process, which greatly enhances the practical relevance of the proposed measure. 
S. C. Hou, X. X. Yi, S. X. Yu and C. H. Oh
quant-ph