Decoherence in a superconducting quantum bit circuit
  Decoherence in quantum bit circuits is presently a major limitation to their use for quantum computing purposes. We present experiments, inspired from NMR, that characterise decoherence in a particular superconducting quantum bit circuit, the quantronium. We introduce a general framework for the analysis of decoherence, based on the spectral densities of the noise sources coupled to the qubit. Analysis of our measurements within this framework indicates a simple model for the noise sources acting on the qubit. We discuss various methods to fight decoherence. 
G. Ithier, E. Collin, P. Joyez, P.J. Meeson, D. Vion, D. Esteve, F.   Chiarello, A. Shnirman, Y. Makhlin, J. Schriefl, and G...