Geometric quantum gate for trapped ions based on optical dipole forces   induced by Gaussian laser beams
  We present an implementation of quantum logic gates via internal state dependent displacements of ions in a linear Paul trap caused by optical dipole forces. Based on a general quantum analysis of the system dynamics we consider specific implementations with alkaline earth ions. For experimentally realistic parameters gate infidelities as low as $10^{-4}$ can be obtained. 
Peter Staanum, Michael Drewsen and Klaus Moelmer