Detecting non-Markovianity of quantum evolution via spectra of dynamical   maps
  We provide an analysis on non-Markovian quantum evolution based on the spectral properties of dynamical maps. We introduce the dynamical analog of entanglement witness to detect non-Markovianity and we illustrate its behaviour with several instructive examples. It is shown that for a certain class of dynamical maps the shape of the body of accessible states provides a simple non-Markovianity witness. 
Dariusz Chru\'sci\'nski, Chiara Macchiavello, Sabrina Maniscalco
quant-ph