Extended entanglement to quantum networks

Farhan Saif, Sami Ul Haq

Liang Wu, Ting Chai, Yanhong Liu +4 more

Quantum network plays a vitally important role in the practical application of quantum information, which requires the deterministic entanglement distribution among multiple remote users. Here, we propose a feasible scheme to deterministically distribute quadripartite entanglement by continuous-variable (CV) polarization states. The quantum server prepares the quadripartite CV polarization entanglement and distributes them to four remote users via optical fiber. In this way, the measurement of CV polarization entanglement is local oscillation free, which makes the long distance entanglement distribution in commercial optical fiber communication networks possible. Furthermore, both the Greenberger-Horne-Zeilinger-like (GHZ-like) and cluster-like polarization entangled states can be distributed among four users by controlling the beam splitter network in quantum server, which are confirmed by the extended criteria for polarization entanglement of multipartite optical modes. The protocol provides the direct reference for experimental implementation and can be directly extended to quantum network with more users, which is essential for a metropolitan quantum network.

Aiman Al-Omari, Saudi Arabia

We suggest two schemes to generate bipartite entangled states by means of a quantum measurement at a third party. The two parties to be entangled have separate entangled states with the third party in modes C1 and C2. In our first scheme we generate entanglement between the two remote parties by considering the modes C1 and C2 indistinguishable. However, in the second scheme we generate entangled states by considering the two modes to be distinguishable. We discuss that the first scheme of remote entanglement generation can be extended to any N number of parties. On making a quantum measurement on this system, we develop quantum networks, based on W-states and other multipartite symmetric entangled states. 1

Aditi Sen

Huan Ye, Xue Yang, Ming‐Xing Luo

Abstract The Greenberger–Horne–Zeilinger (GHZ) paradox shows that it is possible to create a multipartite state involving three or more particles in which the measurement outcomes of the particles are correlated in a way that cannot be explained by classical physics. We extend it to witness quantum networks. We first extend the GHZ paradox to simultaneously verify the GHZ state and Einstein–Podolsky–Rosen states on triangle networks. We then extend the GHZ paradox to witness the entanglement of chain networks consisting of multiple GHZ states. All the present results are robust against the noise.