Realizing Quantum Controlled Phase Flip through Cavity-QED
  We propose a scheme to realize quantum controlled phase flip (CPF) between two rare earth ions embedded in respective microsphere cavity via interacting with a single-photon pulse in sequence. The numerical simulations illuminate that the CPF gate between ions is robust and scalable with extremely high fidelity and low error rate. Our scheme is more applicable than other schemes presented before based on current laboratory cavity-QED technology, and it is possible to be used as an applied unit gate in future quantum computation and quantum communication. 
Yun-Feng Xiao, Xiu-Min Lin, Jie Gao, Yong Yang, Zheng-Fu Han,   Guang-Can Guo