Non-Stationary Noise with Memory in Josephson Junctions (Vol. 49, No. 3)

The current flowing across a Josephson Junction may be thought of as including a memristive component I_M due to the microscopic process of pairs breaking, tunneling and recombining across the junction. As this process is dissipative, it also affects the intrinsic noise of the junction.

In addition to the non-dissipative supercurrent, Josephson junctions also possess a dissipative memristive current component, meaning that the instantaneous resistance of the junction depends on the history of the current. Devices that display this exotic behavior are currently under intense study due to possible applications ranging from fast, high-density, nonvolatile computer memories to neuromorphic computing. In a previous work, the authors suggested a novel device to isolate this current component and thus realize a superconducting memristor. In this work the manifestation of the memristive behaviour in the current noise is considered. The presence of memory renders this noise non-stationary. The authors theoretically characterize both the thermal noise and the 'dynamic'-noise arising across a biased junction, using a mixed time-frequency description. A way to detect this effect of the memristive behaviour on the current noise is also proposed, which should be feasible with current experimental tools.

F. Sheldon, S. Peotta and M. Di Ventra, Phase-dependent noise in Josephson junctions, Eur. Phys. J. Appl. Phys. 81, 10601 (2018)