Dynamics of superconducting nanowires shunted with an external resistor

TL;DR

This study investigates how external shunt resistors influence the coherence, dissipation, and switching behavior of superconducting nanowires, combining experimental measurements with theoretical analysis to identify regimes of simplified modeling.

Contribution

It is the first experimental and theoretical analysis of superconducting nanowires with external shunt resistors, revealing conditions for coherent dynamics and effective circuit modeling.

Findings

Decreasing shunt resistance enhances coherence in nanowire dynamics.

Switching current approaches Bardeen's equilibrium depairing current with lower shunt resistance.

Identifies regimes where nanowires can be modeled as zero-dimensional RCSJ circuits.

Abstract

We present the first study of superconducting nanowires shunted with an external resistor, geared towards understanding and controlling coherence and dissipation in nanowires. The dynamics is probed by measuring the evolution of the V-I characteristics and the distributions of switching and retrapping currents upon varying the shunt resistor and temperature. Theoretical analysis of the experiments indicates that as the value of the shunt resistance is decreased, the dynamics turns more coherent presumably due to stabilization of phase-slip centers in the wire and furthermore the switching current approaches the Bardeen's prediction for equilibrium depairing current. By a detailed comparison between theory and experimental, we make headway into identifying regimes in which the quasi-one-dimensional wire can effectively be described by a zero-dimensional circuit model analogous to the RCSJ (resistively and capacitively shunted Josephson junction) model of Stewart and McCumber. Besides its fundamental significance, our study has implications for a range of promising technological applications.