Experimental verification of genuine multipartite entanglement without shared reference frames

Quantum entanglement is an essential resource for quantum information processing, either for quantum communication or for quantum computation. The multipartite case of entanglement, especially the so called genuine multipartite entanglement, has significant importance for multipartite quantum information protocols. Thus, it is a natural requirement to experimentally verify multipartite quantum entanglement when performing many quantum information tasks. However, this is often technically challenging due to the difficulty of building a shared reference frame among all involved parties, especially when these parties are distant from each other. In this paper, we experimentally verify the genuine tripartite entanglement of a three-photon Greenberger-Horne-Zeilinger state without shared reference frames. A high probability 0.79 of successfully verifying the genuine tripartite entanglement is achieved when no reference frame is shared. In the case of sharing only one common axis, an even higher success probability of 0.91 is achieved.