Discrete breathers in nonlinear lattices: Experimental detection in a Josephson array

TL;DR

This paper experimentally investigates discrete breathers in a Josephson-junction array, demonstrating their existence under various conditions and identifying key factors influencing their stability and formation.

Contribution

It provides the first experimental detection of discrete breathers in a Josephson array and explores their stability and formation mechanisms.

Findings

Breathers exist over a range of bias currents and temperatures.

Maximum bias current for breathers is proportional to the depinning current.

Instability due to junction retrapping leads to multi-site breathers.

Abstract

We present an experimental study of discrete breathers in an underdamped Josephson-junction array. Breathers exist under a range of dc current biases and temperatures, and are detected by measuring dc voltages. We find the maximum allowable bias current for the breather is proportional to the array depinning current while the minimum current seems to be related to a junction retrapping mechanism. We have observed that this latter instability leads to the formation of multi-site breather states in the array. We have also studied the domain of existence of the breather at different values of the array parameters by varying the temperature.