Twin-field quantum key distribution with heralded single photon source Fen Zhou, Wenxiu Qu, Jipeng Wang, Tianqi Dou, Zhenhua Li, Shunyu Yang, Zhongqi Sun, Guoxing Miao and Haiqiang Ma Eur. Phys. J. D, 74 9 (2020) 185 Published online: 17 September 2020 DOI: 10.1140/epjd/e2020-10219-0