An efficient scheme for the deterministic maximal entanglement of N   trapped ions
  We propose a method for generating maximally entangled states of N two-level trapped ions. The method is deterministic and independent of the number of ions in the trap. It involves a controlled-NOT acting simultaneously on all the ions through a dispersive interaction. We explore the potential application of our scheme for high precision frequency standards. 
J. Steinbach and C.C. Gerry