Author Affiliations

H.-R. Xia,^* J. I. Cirac,^† S. Swartz, B. Kohler,^‡ D. S. Elliott,^§ J. L. Hall,^** and P. Zoller

¹Joint Institute for Laboratory Astrophysics, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 USA

^*Permanent address, Department of Physics, East China Normal University, Shanghai 200062, China.

^†Permanent address, Departamento de Fisica Aplicada, Facultad de Ciencias Quimica, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain.

^‡Permanent address, Department of Physics, University of California, Riverside, California.

^§Permanent address, School of Electrical Engineering, Purdue University, West Lafayette, Indiana.

^**Quantum Physics Division, National Institute of Standards and Technology.