We report a new type of anomalous diffusion in chaotic systems with periodic symmetry. It is characterized by mean square displacements diverging faster than linearly in time. By a comparison of power spectra we conclude that the phenomenon has occurred in a recent observation of $\frac{1}{f}$ noise in Josephson junctions.

• Received 29 October 1984

DOI:https://doi.org/10.1103/PhysRevLett.54.616