Phase Control of Trapped Ion Quantum Gates
  There are several known schemes for entangling trapped ion quantum bits for large-scale quantum computation. Most are based on an interaction between the ions and external optical fields, coupling internal qubit states of trapped-ions to their Coulomb-coupled motion. In this paper, we examine the sensitivity of these motional gate schemes to phase fluctuations introduced through noisy external control fields, and suggest techniques to suppress the resulting phase decoherence. 
P J Lee, K-A Brickman, L Deslauriers, P C Haljan, L-M Duan and C   Monroe