Distillation of free entanglement from bound entangled states using weak measurements

TL;DR

This paper introduces a novel protocol that uses weak measurements and an ancillary system to reliably convert bound entangled states into free entangled states with nonzero probability, optimizing entanglement distillation.

Contribution

The authors present a new scheme for distilling free entanglement from bound-entangled states using weak measurements and ancillary systems, with analysis of entanglement costs.

Findings

Free entanglement can be generated from bound-entangled states with nonzero probability.

Weaker measurements lead to higher free entanglement and lower costs.

A lower bound on the entanglement cost of the protocol is derived.

Abstract

We propose a scheme for distillation of free bipartite entanglement from bipartite bound-entangled states. The crucial element of our scheme is an ancillary system that is coupled to the initial bound-entangled state via appropriate weak measurements. We show that in this protocol free entanglement can be always generated with nonzero probability by using a single copy of the bound-entangled state. We also derive a lower bound on the entanglement cost of the protocol, and conclude that, on average, applying weaker measurements results in relatively higher values of free entanglement as well as lower costs.