Almost Markovian processes from closed dynamics

@article{FigueroaRomero2018AlmostMP,
  title={Almost Markovian processes from closed dynamics},
  author={Pedro Figueroa-Romero and Kavan Modi and Felix A. Pollock},
  journal={Quantum},
  year={2018}
}
It is common, when dealing with quantum processes involving a subsystem of a much larger composite closed system, to treat them as effectively memory-less (Markovian). While open systems theory tells us that non-Markovian processes should be the norm, the ubiquity of Markovian processes is undeniable. Here, without resorting to the Born-Markov assumption of weak coupling or making any approximations, we formally prove that processes are close to Markovian ones, when the subsystem is… 

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