Quantum entanglement swapping between two multipartite entangled states

TL;DR

This paper reports an experimental demonstration of entanglement swapping between two independent multipartite entangled states, advancing quantum network capabilities by merging complex entangled states through joint measurements and classical feedforward.

Contribution

It presents the first experimental realization of entanglement swapping between two multipartite GHZ states, including a hybrid GHZ-EPR state, with analysis of transmission loss effects.

Findings

Successful entanglement swapping between two tripartite GHZ states.

Implementation of entanglement swapping between GHZ and EPR states.

Analysis of entanglement robustness under transmission loss.

Abstract

Quantum entanglement swapping is one of the most promising ways to realize the quantum connection among local quantum nodes. In this Letter, we present an experimental demonstration of the entanglement swapping between two independent multipartite entangled states, each of which involves a tripartite Greenberger-Horne-Zeilinger (GHZ) entangled state of an optical field. The entanglement swapping is implemented deterministically by means of a joint measurement on two optical modes coming from the two multipartite entangled states respectively and the classical feedforward of the measurement results. After entanglement swapping the two independent multipartite entangled states are merged into a large entangled state in which all unmeasured quantum modes are entangled. The entanglement swapping between a tripartite GHZ state and an Einstein-Podolsky-Rosen entangled state is also demonstrated and the dependence of the resultant entanglement on transmission loss is investigated. The presented experiment provides a feasible technical reference for constructing more complicated quantum networks.