Entangled coherent states and squeezing in N trapped ions
  We consider a resonant bichromatic excitation of N trapped ions that generates displacement and squeezing in their collective motion conditioned to their ionic internal state, producing eventually Scrhodinger cat states and entangled squeezing. Furthermore, we study the case of tetrachromatic illumination or producing the so called entangled coherent states in two motional normal modes. 
E. Solano, R. L. de Matos Filho, and N. Zagury