Noise sequences of infinite matrices and their applications to the   characterization of the canonical phase and box localization observables
  Noise sequences of infinite matrices associated with covariant phase and box localization observables are defined and determined. The canonical observables are characterized within the relevant classes of observables as those with asymptotically minimal or minimal noise, i.e., the noise tending to 0 or having the value 0. 
Pekka Lahti, Maciej J. Maczynski, Egon Scheffold, Kari Ylinen