Maximally non-Markovian quantum dynamics without environment-to-system backflow of information
Adrián A. Budini · Physical Review A · 2018
The degree of non-Markovianity allows one to characterize quantum evolutions that depart from a Markovian regime in a similar way as the Schmidt number measures the degree of entanglement of pure states. Maximally non-Markovian dynamics are analogous to maximally entangled states [D. Chru\ifmmode \acute{s}\else \'{s}\fi{}ci\ifmmode \acute{n}\else \'{n}\fi{}ski and S. Maniscalco, Phys. Rev. Lett. 112, 120404 (2014)]. Here we demonstrate that there exists a class of maximally non-Markovian quantum evolutions where the associated environment (degrees of freedom not belonging to the system) obeys a Markovian (memoryless) dynamics, which in turn is unperturbed by the system state or dynamics. These properties imply the absence of any ``physical environment-to-system backflow of information.'' Non-Markovian features (as usual in quantum systems coupled to dissipative classical degrees of freedom) arise from a unidirectional dependence of the system dynamics on the reservoir states.