Coherent coupling of a superconducting flux qubit to an electron spin ensemble in diamond. - Xiaobo Zhu; Shiro Saito; Alexander Kemp; Kosuke Kakuyanagi; Shin-ichi Karimoto; Hayato Nakano; William J. Munro; Yasuhiro Tokura; Mark S. Everitt; Kae Nemoto; Makoto Kasu; Norikazu Mizuochi; et al. (Nat., 2011)