Manipulating the Quantum State of an Electrical Circuit
  We have designed and operated a superconducting tunnel junction circuit that behaves as a two-level atom: the ``quantronium''. An arbitrary evolution of its quantum state can be programmed with a series of microwave pulses, and a projective measurement of the state can be performed by a pulsed readout sub-circuit. The measured quality factor of quantum coherence Qphi=25000 is sufficiently high that a solid-state quantum processor based on this type of circuit can be envisioned. 
D. Vion, A. Aassime, A. Cottet, P. Joyez, H. Pothier, C. Urbina, D.   Esteve, M.H. Devoret (CEA/Saclay, Drecam/Spec, France)