Protocols to share genuine multipartite entanglement employing copies of biseparable states

TL;DR

This paper introduces a protocol for generating genuine multipartite entanglement from biseparable states in multi-party quantum systems, demonstrating efficiency improvements and activation of nonlocal correlations without joint measurements.

Contribution

The authors present a novel protocol that activates genuine multipartite entanglement from biseparable states in multi-party systems without joint measurements, extending previous results.

Findings

Two copies of rank-two biseparable states suffice for three-qutrit systems.

The protocol generalizes to any number of parties.

Activation of genuinely nonlocal correlations is achieved.

Abstract

Sharing genuine multipartite entanglement by considering collective use of copies of biseparable states, which are entangled across all bipartitions but lack genuine multipartite entanglement at the single-copy level, plays a central role in several quantum information processing protocols, and has been referred as genuine multipartite entanglement activation. We present a protocol for three-qutrit systems showing that two copies of rank-two biseparable states, entangled across every bipartition, are sufficient to generate a genuinely multipartite entangled state with nonzero probability. This contrasts with the three-qubit scenario where many copies of biseparable states might be required for sharing genuine multipartite entanglement. We subsequently generalize our protocols to the case of an arbitrary number of parties. Our protocol does not rely on the implementation of joint measurements on the copies of states. Interestingly, the proposed construction naturally leads to the activation of genuinely nonlocal correlations, yielding a result that is stronger than genuine multipartite entanglement activation alone.