NMR-like control of a quantum bit superconducting circuit

Coherent superpositions of quantum states have already been demonstrated in different super-conducting circuits based on Josephson junctions. These circuits are now considered for implementing quantum bits. We report on experiments in which the state of a qubit circuit, the quantronium, is efficiently manipulated using methods inspired from nuclear magnetic resonance (NMR): multipulse sequences are used to perform arbitrary operations, to improve their accuracy, and to fight decoherence.