RANDOMIZATION OF THE PHASE AFTER SUPPRESSION OF THE JOSEPHSON COUPLING

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