Realization and characterization of a SQUID flux qubit with a direct readout scheme

Superconducting devices based on the Josephson effect are promising candidates for the implementation of quantum computing. After the experimental demonstration of the coherent manipulation and coupling of Josephson qubits 1-8 , the actual efforts concern the design and realization of new optimised elements with small decoherence, efficient readout, simple and complete coherent manipulation, integration and coupling of more qubits. In this direction we have realized a double SQUID qubit with a fully gradiometric configuration and a readout scheme based on the direct injection of current in a large junction in the SQUID loop. We present a preliminary experimental characterization at 4.2 K showing the capability to perform a highly efficient discrimination of the qubit flux states.