Yong-Su Kim

We investigate an entanglement swapping protocol using photon-number-encoded states to alleviate quantum channel losses without requiring quantum memories. The protocol achieves entanglement distribution probability scaling linearly with channel transmission. Unbalanced channel losses can degrade the entanglement, but this is compensated by optimally adjusting the initial states.

It is usually essential to have a common reference frame between two communication parties to perform quantum communication. Notably,  Reference-Frame-Independent Quantum Key Distribution (RFI-QKD) provides a practical way to generate secret keys between two remote parties without sharing standard reference frames. Here, we have shown that the RFI-QKD protocol can be expanded into a multiparty system with Greenberger-Horne-Zeilinger (GHZ) entangled state. We derive the asymptotic key rate and perform the proof-of-principle experiment to verify the proposed multiparty protocols feasibility. Considering that sharing a common reference frame becomes more difficult as the number of parties increases, our protocol provides a new path to implement multipartite quantum communication in real world.