Quantum phase transitions and coherent tunneling in a bilayer of ultracold atoms with dipole interactions A.C. Ji, Q. Sun, X.H. Hu, W.M. Liu and X.C. Xie Eur. Phys. J. B, 85 6 (2012) 194 Published online: 12 June 2012 DOI: 10.1140/epjb/e2012-30151-x