Efficient linear optical generation of a multipartite W state via a quantum eraser

Entanglement among multiple particles is a keystone for not only fundamental research on quantum information but also various practical quantum information applications. In particular, the W state has attracted a lot of attention due to the robustness against particle loss and the applications in multiparty quantum communication. However, it is challenging to generate a photonic W state with a large number of photons, since the N-photon W state requires superposition among N probability amplitudes. In this paper, we propose an efficient linear optical scheme to generate N-photon W states via quantum erasure. The success probability of our protocol polynomially decreases as the number of photons increases. We also discuss the experimental feasibility of our protocol and anticipate that one can efficiently generate tens of photonic W states with our scheme using currently available quantum photonics technologies.