Distribution of Multiplexed Continuous-Variable Entanglement for Quantum Networks

Quantum networks, the backbone of the future quantum internet, require flexible and precise control to faithfully share entanglement with different users. These networks will allow multiple applications including distributed quantum computation and information theoretic secure communication. In this scenario, orbital angular momentum (OAM) can be employed to enhance the capacity of quantum information processing and to distribute quantum entanglement in an efficient and scalable way with multiple users. Here, a method for realizing a multiplexed continuous variable (CV) quantum entanglement distribution based on a four-wave mixing process combined with an active routing technique is experimentally demonstrated. By exploiting Sagnac-based OAM sorters, the OAM entanglement can be distributed and measured with the different users in a quasi-complete star network configuration. The generations of multiple sets of OAM multiplexed bipartite CV entanglement with four users and six users are proposed and demonstrated here. In addition, the propagation of one mode through a 1 km of single-mode fiber shows the applicability of this approach. These results propose and demonstrate a new method for distributing CV entanglement in a quantum network enlarging the range of applicability of CV quantum information protocols.