Non-Markovian dynamics for an open two-level system without rotating wave approximation: indivisibility versus backflow of informationH.S. Zeng, N. Tang, Y.P. Zheng and T.T. XuEur. Phys. J. D, 66 10 (2012) 255DOI: https://doi.org/10.1140/epjd/e2012-30354-3