Quantum gates using electronic and nuclear spins of Yb+ in a magnetic field gradient K.L. Wang, M. Johanning, M. Feng, F. Mintert and C. Wunderlich Eur. Phys. J. D, 63 1 (2011) 157-164 Published online: 17 May 2011 DOI: 10.1140/epjd/e2011-20108-2