Quantum state estimation of multi-partite single photon path entanglement via local measurements

TL;DR

This paper presents a practical method for estimating multipartite single photon path entanglement using only local measurements, facilitating easier implementation in quantum network experiments.

Contribution

It introduces a novel local measurement-based approach for quantum state estimation of multipartite entangled states, demonstrated experimentally on a 3-qubit W-state.

Findings

Successful reconstruction of a 3-qubit W-state density matrix

Method is practical and easy to implement with reasonable assumptions

Enables estimation of distributed entanglement in quantum networks

Abstract

Multipartite entanglement plays a critical role in various applications of quantum internet. In these applications, the entanglement is usually shared by the distant parties. Experimentally, the distributed entanglement should be estimated by only local measurements. Furthermore, for network experiments, it is desirable to employ measurement techniques that are straightforward to implement. In this paper, we propose a method to measure arbitrary multipartite single photon path entangled states by only local measurements. By considering practically reasonable assumptions, our method is relatively easy to implement. We experimentally demonstrate the utility of this method by reconstructing the density matrix of a 3-qubit W-state.