Elimination of thermal bistability in superconducting weak links by an inductive shunt

TL;DR

This paper demonstrates that an inductive shunt can eliminate thermal bistability in superconducting weak links, enabling nonhysteretic operation with large voltage oscillations through nonlinear dynamics.

Contribution

The study introduces a novel inductive shunt approach that destabilizes thermal hysteresis in superconducting weak links, supported by a dynamic thermal model.

Findings

Inductive shunt induces nonlinear dynamics in superconducting weak links.

Thermal bistability can be suppressed, leading to nonhysteretic behavior.

Large voltage oscillations observed in superconducting quantum interference devices.

Abstract

The quantum phase-coherent behavior of superconducting weak links (WL) is often quenched in the finite voltage state, due to the heat dissipation and related thermal hysteresis. The latter can be reduced by improving heat evacuation and/or by lowering the critical current, so that a phase-dynamic regime is obtained, albeit over a narrow bias-current and temperature range. Here we demonstrate that an inductive shunt with well-chosen parameters introduces unexpected nonlinear dynamics that destabilize an otherwise stable fixed point in the dissipative branch. This leads to a nonhysteretic behavior with large voltage oscillations in intrinsically hysteretic WL-based micron-size superconducting quantum interference devices. A dynamic thermal model quantitatively describes our observations and further allows us to elaborate on the optimal shunting conditions.