Discrete breathers in nonlinear lattices: experimental detection in a josephson array.

Area of Science:

• Condensed Matter Physics
• Nonlinear Dynamics
• Superconductivity

Background:

• Discrete breathers are localized nonlinear modes that can exist in nonlinear discrete systems.
• Josephson-junction arrays are promising systems for studying nonlinear phenomena due to their tunable parameters.

Purpose of the Study:

• To experimentally detect discrete breathers in an underdamped Josephson-junction array.
• To investigate the influence of dc current bias and temperature on breather existence.
• To understand the mechanisms governing breather formation and stability.

Main Methods:

• Experimental setup utilizing an underdamped Josephson-junction array.
• Detection of discrete breathers through measurement of dc voltages.
• Systematic variation of dc current bias and temperature to map the breather's domain of existence.

Main Results:

• Experimental confirmation of discrete breathers in the Josephson-junction array.
• Breather existence observed across a range of dc current biases and temperatures.
• Maximum bias current for breathers found proportional to array depinning current.
• Minimum bias current linked to junction retrapping, leading to multisite breather states.
• Domain of breather existence studied by varying temperature and array parameters.

Conclusions:

• Discrete breathers are experimentally realized in Josephson-junction arrays.
• Breather stability is governed by array depinning and junction retrapping mechanisms.
• The study provides insights into nonlinear dynamics in superconducting circuits.