Single Phase Slip Limited Switching Current in 1-Dimensional Superconducting Al Nanowires

TL;DR

This study investigates the switching current behavior in 1D superconducting aluminum nanowires, revealing the roles of thermal activation and quantum tunneling of phase slips in the transition from superconducting to normal states.

Contribution

It provides experimental evidence that a single phase slip triggers switching, with a detailed analysis of temperature-dependent fluctuations and heat dissipation effects.

Findings

Switching current follows depairing critical current but is lower.

Fluctuations exhibit three temperature-dependent behaviors.

Quantum tunneling of phase slips dominates at low temperatures.

Abstract

An Aluminum nanowire switches from superconducting to normal as the current is increased in an upsweep. The switching current (I_s) averaged over upsweeps approximately follows the depairing critical current (I_c) but falls below it. Fluctuations in I_s exhibit three distinct regions of behaviors and are non-monotonic in temperature: saturation well below the critical temperature T_c, an increase as T^{2/3} at intermediate temperatures, and a rapid decrease close to T_c. Heat dissipation analysis indicates that a single phase slip is able to trigger switching at low and intermediate temperatures, whereby the T^{2/3} dependence arises from the thermal activation of a phase slip, while saturation at low temperatures provides striking evidence that the phase slips by macroscopic quantum tunneling.