  Entanglement among multiple particles is a keystone for not only fundamental
research on quantum information but also various practical quantum information
applications. In particular, 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 photonic W state with
large number of photons since 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 state via quantum erasure. The success
probability of our protocol polynomially decreases as the number of photons
increase. We also discuss the experimental feasibility of our protocol, and
anticipate that one can efficiently generate tens of photonic W state with our
scheme using currently available quantum photonics technologies.
