Hidden entanglement, system-environment information flow and   non-Markovianity
  It is known that entanglement dynamics of two noninteracting qubits, locally subjected to classical environments, may exhibit revivals. A simple explanation of this phenomenon may be provided by using the concept of hidden entanglement, which signals the presence of entanglement that may be recovered without the help of nonlocal operations. Here we discuss the link between hidden entanglement and the (non-Markovian) flow of classical information between the system and the environment. 
A. D'Arrigo, G. Benenti, R. Lo Franco, G. Falci, E. Paladino
quant-ph