We present an experimental study of the effective dissipation of a fully integrated ${\mathrm{N}\mathrm{b}/\mathrm{A}\mathrm{l}\mathrm{O}}_x/\mathrm{Nb}$ Josephson device consisting of a rf superconducting quantum interference device (SQUID) coupled to a readout system based on a dc SQUID sensor. In the classical regime data on the decay rate from the metastable flux states of rf SQUID are reported. The low dissipation level and the good insulation of the probe from the external noise are encouraging in view of building a macroscopic quantum device.

• Received 28 October 2002

DOI:https://doi.org/10.1103/PhysRevB.67.132504