We propose a robust and scalable scheme to generate an N-qubit W state among separated quantum nodes (cavity-QED systems) by using linear optics and postselections. The present scheme inherits the robustness of the Barrett-Kok scheme [Phys. Rev. A {\bf 71}, 060310(R) (2005)]. The scalability is also ensured in the sense that an arbitrarily large N-qubit W state can be generated with a quasi-polynomial overhead ∼2O[(log2N)2]. The process to breed the W states, which we introduce to achieve the scalability, is quite simple and efficient, and can be applied for other physical systems.
@article{arxiv.1102.4682,
title = {Robust and Scalable Scheme to Generate Large-Scale Entanglement Webs},
author = {Keisuke Fujii and Haruki Maeda and Katsuji Yamamoto},
journal= {arXiv preprint arXiv:1102.4682},
year = {2015}
}