Activating bound entanglement in multiparticle systems -: art. no. 022302

We analyze the existence of activable bound entangled states in multiparticle systems. We first give a series of examples that illustrate some different ways in which bound entangled states can be activated by letting some of the parties share maximally entangled states. Then, we derive necessary conditions for a state to be distillable as well as to be activable. These conditions turn out to be also sufficient for a certain family of multiqubit states. We use these results to explicitely construct states displaying properties related to bound entanglement and its activation.