Scalable Source of Multipartite Entangled States of Light

Continuous variable multipartite entanglement (CVME) is a valuable resource for quantum information science and quantum computation, as it can enable a stronger violation of bell-type inequalities. Due to the strong non-locality, it can benefit applications such as quantum teleportation, dense coding, and quantum sensing. It is also a necessary resource for applications such as controlled quantum secure direct communications in which a third party acts as a controller for secure communication between any two parties in a network. Experimental realizations of CVME have already been demonstrated with different configurations, such as cascaded parametric amplifiers, beam splitter networks with input single mode squeezed states of light, and time-bin multiplexing of squeezed light sources in the temporal domain. Here, we present our preliminary experimental results on the implementation of a scheme to generate genuine CVME through the use of spatial modes. The system consists of an SU(1,1) like interferometer with two four wave mixing processes serving as the source and mixing element for the different spatial modes. The setup contains only two active elements and offers the advantage of providing a simpler and scalable technique for the generation and verification of genuine multipartite entanglement in the spatial domain.