Superactivation of Bound Entanglement

TL;DR

This paper demonstrates that combining certain bound-entangled states can produce a distillable entangled state, revealing superadditivity and the true bound-entangled nature of some states.

Contribution

It proves superactivation of bound entanglement and shows some bound-entangled states cannot become unentangled asymptotically.

Findings

Two bound-entangled states can produce a distillable state when combined.

Unlockable bound-entangled states are not asymptotically unentangled.

First proof of true bound-entanglement in the asymptotic limit.

Abstract

We show that, in a multi-party setting, two non-distillable (bound-entangled) states tensored together can make a distillable state. This is an example of true superadditivity of distillable entanglement. We also show that unlockable bound-entangled states cannot be asymptotically unentangled, providing the first proof that some states are truly bound-entangled in the sense of being both non-distillable and non-separable asymptotically.