Entropic Superactivation of Backflow of Information

In this work, we analyze the so-called Superactivation of Backflow of Information, namely the activation of memory effects for a bipartite system that are not detectable when only one party is considered. In particular, we study this phenomenon from the point of view of entropy revivals. We prove that such an effect is never manifested as revivals of the 2-Renyi entropy or, equivalently, of the purity of the state. Conversely, we show that the von Neumann entropy is able to expose SBFI for a class of non-Markovian evolutions.