RANDOMIZATION OF THE PHASE AFTER SUPPRESSION OF THE JOSEPHSON COUPLING

The randomization of the relative phase between two isolated supercond uctors or superfluids which have been previously linked by a Josephson junction is analyzed theoretically. Several time scales are identifie d and their order of magnitude is estimated. It is concluded that the relative phase can remain well defined for observable times in the cas e of superfluids, while it is quickly randomized due to quantum spread ing in the case of superconductors. Quantum randomization can however be strongly slowed down if the two superconductors are coupled to a co mmon normal metal reservoir. In the absence of noise, the relative pha se may display a recurrent dynamics. Possible experiments to explore t he phase dynamics are suggested.