Extreme events in a network of heterogeneous Josephson junctions

TL;DR

This paper investigates rare large spiking events, termed extreme events, in a heterogeneous network of Josephson junctions, revealing their origin, dynamics, and dependence on network parameters.

Contribution

It introduces a detailed analysis of extreme events in Josephson junction networks, highlighting the role of heterogeneity and repulsive interactions in their emergence and behavior.

Findings

Extreme events are larger than statistically significant thresholds.

EE can be tracked across different sub-groups with distinct dynamics.

The inter-event-intervals follow a Poisson distribution.

Abstract

We report rare and recurrent large spiking events in a heterogeneous network of superconducting Josephson junctions (JJ) connected through a resistive load and driven by a radio-frequency (rf) current in addition to a constant bias. The intermittent large spiking events show characteristic features of extreme events (EE) since they are larger than a statistically defined significant height. Under the influence of repulsive interactions and an impact of heterogeneity of damping parameters, the network splits into three sub-groups of junctions, one in incoherent rotational, another in coherent librational motion and a third sub-group originating EE. We are able to scan the whole population of junctions with their distinctive individual dynamical features either in EE mode or non-EE mode in parameter space. EE migrates spatially from one to another sub-group of junctions depending upon the repulsive strength and the damping parameter. For a weak repulsive coupling, all the junctions originate frequent large spiking events, in rotational motion when the average inter-spike-interval (ISI) is small, but it increases exponentially with repulsive interaction; it largely deviates from its exponential growth at a break point where EE triggers in a sub-group of junctions. The probability density of inter-event-intervals (IEI) in the subgroup exhibits a Poisson distribution. EE originates via bubbling instability of in-phase synchronization.