Macroscopic quantum device based on a rf SQUID system

The growing amount of theoretical interest in the area of quantum computing have stimulated in recent years research with the aim of developing a corresponding technology. Superconducting Josephson systems appear to be among the most promising candidates. We present the characterization of a fully integrated Josephson device consisting of a rf SQUID coupled to a readout system based on a dc SQUID sensor. We report measurements of the dc SQUID performances showing a high intrinsic responsivity and a low flux noise, giving a good signal to noise ratio in the small signal mode. In the classical regime data on the decay rate from the metastable flux states of rf SQUID are also reported. The low dissipation level and the good insulation of the probe from the external noise are encouraging in view of macroscopic quantum experiments. Work is in progress to improve the design of the device to increase its application capability toward the quantum regime.