Superactivation of bound entanglement

Asymptotically entangled states which exist from which no pure entanglement can be distilled were shown. Moreover, a surprising fact that distillable entanglement was not additive by showing two undistillable asymptotically entangled states that when combined give a distillable state was shown as well. This paper presents a four-party example of a state that was asymptotically entangled but not distillable.