Self-healing of multipartite entanglement in optical quantum networks

Multipartite entanglement serves as an essential resource for constructing quantum networks and makes it possible to realize multi-user quantum information protocols outperforming their classical counterparts. Unfortunately, multipartite entanglement is fragile when distributed in complex environments. Therefore, it is urgent to address the issue of multipartite entanglement decoherence caused by complex environments. Here we demonstrate the self-healing of multipartite continuous-variable (CV) entanglement after an obstruction. In our experiment, the tripartite entanglement destroyed by the obstruction-introduced noise and loss can self-heal after free-space propagation of a certain distance due to the self-healing property of a Bessel-Gaussian (BG) beam. We show that the BG beam provides a more robust mode basis for free-space CV quantum entanglement distribution than the widely used fundamental Gaussian beam under similar conditions. In addition, we also demonstrate the self-healing of five sets of tripartite entanglement and 10 sets of bipartite entanglement in orbital-angular-momentum-multiplexed optical quantum networks. Our results pave the way for constructing obstruction-tolerant high-capacity CV optical quantum networks. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement