Deterministic distribution of multipartite entanglement and steering in a quantum network by separable states

TL;DR

This paper demonstrates a method for deterministically distributing Gaussian entanglement and steering among multiple users in a quantum network using separable states, which is robust against loss and enables advanced quantum communication tasks.

Contribution

The authors experimentally show that entanglement and steering can be distributed among independent users via separable states, creating a new approach for quantum network resource sharing.

Findings

Distributed Gaussian entanglement is robust against channel loss.

One-way Gaussian steering among users is achieved.

Separable states can be used to generate entanglement during distribution.

Abstract

As two valuable quantum resources, Einstein-Podolsky-Rosen entanglement and steering play important roles in quantum-enhanced communication protocols. Distributing such quantum resources among multiple remote users in a network is a crucial precondition underlying various quantum tasks. We experimentally demonstrate the deterministic distribution of two- and three-mode Gaussian entanglement and steering by transmitting separable states in a network consisting of a quantum server and multiple users. In our experiment, entangled states are not prepared solely by the quantum server, but are created among independent users during the distribution process. More specifically, the quantum server prepares separable squeezed states and applies classical displacements on them before spreading out, and users simply perform local beam-splitter operations and homodyne measurements after they receive separable states. We show that the distributed Gaussian entanglement and steerability are robust against channel loss. Furthermore, one-way Gaussian steering is achieved among users that is useful for further directional or highly asymmetric quantum information processing.