Measurement of Arbitrary Observables of a Trapped Ion
  We describe a method to perform a single quantum measurement of an arbitrary observable of a single ion moving in a harmonic potential. We illustrate the measurement procedure with explicit examples, namely the position and phase observables. 
S. A. Gardiner (Innsbruck), J. I. Cirac (Castilla-La Mancha), and P.   Zoller (Innsbruck)