Non-dissipative decoherence bounds on quantum computation
  We investigate the capabilities of a quantum computer based on cold trapped ions in presence of non-dissipative decoherence. The latter is accounted by using the evolution time as a random variable and then averaging on a properly defined probability distribution. Severe bounds on computational performances are found. 
Stefano Mancini and Rodolfo Bonifacio (INFM, Univ. Milano, Italy)