Maximizing switching current of superconductor nanowires via improved impedance matching

TL;DR

This paper introduces an improved impedance matching circuit that enhances the switching current in superconductor nanowires by effectively releasing phase slip transitions, with potential applications in superconducting devices and quantum phase slip research.

Contribution

It presents a novel impedance matching technique that significantly increases the switching current in superconductor nanowires by reducing reflection effects caused by impedance mismatching.

Findings

Switching current increased from 8.0 μA to 12.2 μA with impedance matching.

Impedance matching reduces reflection, maximizing switching current.

Voltage pulses enable direct registration of phase slip transitions.

Abstract

The temporary resistance triggered by phase slip will result in the switching of superconductor nanowire to a permanent normal state, decreasing the switching current. In this letter, we propose an improved impedance matching circuit that releases the transition triggered by phase slips to the load resistor through the RF port of a bias tee. The transportation properties with different load resistors indicate that the switching current decreases due to the reflection caused by impedance mismatching, and is maximized by optimized impedance matching. Compared to the same setup without impedance matching circuit, the switching current was increased from 8.0 micro A to 12.2 micro A in a niobium nitride nanowire after releasing the temporary transition triggered by phase slips. The leakage process with impedance matching outputs a voltage pulse which enables the user to directly register the transition triggered by phase slips. The technique for maximizing the switching current has potential practical application in superconductor devices, and the technique for counting phase slips may be applied to explore the quantum behavior of phase slips.