The impact of kinetic inductance on the critical current oscillations of nanobridge SQUIDs

TL;DR

This paper investigates how the kinetic inductance of MoGe nanobridges affects the critical current oscillations in SQUIDs, revealing controllable properties for advanced superconducting device design.

Contribution

It demonstrates lithographic control of nanobridge kinetic inductance and its impact on SQUID characteristics, enabling tunable superconducting device functionalities.

Findings

Linear current-phase relation at low temperatures

Kinetic inductance scales with nanobridge aspect ratio

Tunable SQUID sensitivity and critical current maxima

Abstract

In this work, we study the current phase relation ($C\Phi R$) of lithographically fabricated molybdenum germanium (MoGe) nanobridges, which is intimately linked to the nanobridge kinetic inductance. We do this by imbedding the nanobridges in a SQUID. We observe that for temperatures far below $T_c$, the $C\Phi R$ is linear as long as the condensate is not weakened by the presence of supercurrent. We demonstrate lithographic control over the nanobridge kinetic inductance, which scales with the nanobridge aspect ratio. This allows to tune the SQUID $I_c(B)$ characteristic. The SQUID properties that can be controlled in this way include the SQUID sensitivity and the positions of the critical current maxima. These observations can be of use for the design and operation of future superconducting devices such as magnetic memories or flux qubits.