Measurement-based Multipartite Entanglement Inflation

TL;DR

This paper introduces a measurement-based protocol called multipartite entanglement inflation for creating large-scale entangled states from smaller ones, revealing counterintuitive effects of initial state entanglement and auxiliary system choices.

Contribution

It proposes a novel measurement-based method for expanding multipartite entanglement, analyzing its effectiveness with various initial states and auxiliary systems.

Findings

Maximally entangled states can be less effective than non-maximally entangled states for entanglement inflation.

Haar-random pure states with moderate entanglement perform well in the protocol.

Unentangled auxiliary systems can sometimes outperform entangled ones in the protocol.

Abstract

Generating entanglement between more parties is one of the central tasks and challenges in the backdrop of building quantum technologies. Here we propose a measurement-based protocol for producing multipartite entangled states which can be later fed into some network for realizing suitable quantum protocols. We consider weak entangling measurement on two parties as the basic unit of operation to create entanglement between more parties starting from an entangled state with a lesser number of parties and auxiliary systems in the form of a single-qubit or entangled state itself. We call the introduced expansion procedure, "multipartite entanglement inflation". In the context of inflating bipartite entanglement to more number of parties, surprisingly, maximally entangled states as inputs turn out to be worse than that of the non-maximally entangled states, Haar uniformly generated pure states having a moderate amount of entanglement and the Werner state with a certain threshold noise. We also report that the average multipartite entanglement created from the initial Greenberger Horne Zeilinger- and the W- class states are almost same. Interestingly, we also observe that for Haar uniformly generated pure states, unentangled auxiliary systems are sometimes more advantageous than the protocol with multiple copies of the initial entangled states.