A theoretical demonstration that the single-mode spin-boson model at strong coupling can show non-Markovian memory effects even where a timescale-separation argument predicts Markovian dynamics. Applying the Lang-Firsov polaron transformation to reduce the effective coupling, the authors show that taking the time-convolutionless master equation to its infinite-time (Markovian) limit spuriously yields decoherence-free evolution, whereas keeping finite time limits reveals genuine non-Markovianity, quantified by non-monotonic l1-norm coherence, with population and coherence revivals over an intermediate coupling range that disappears only in the very large coupling limit.
An open quantum system is a quantum system coupled to a surrounding environment (bath); its evolution is Markovian when information flows only one way, system to bath, and non-Markovian when informat…