Overdamped van der Waals Josephson junctions by area engineering

TL;DR

This paper demonstrates a minimally invasive microfabrication method to precisely control the junction area in van der Waals NbSe2 Josephson junctions, enabling the realization of overdamped devices suitable for quantum technology applications.

Contribution

It introduces a new fabrication process that preserves material quality while allowing precise junction area control for overdamped Josephson junctions.

Findings

Successfully fabricated both underdamped and overdamped NbSe2 JJs.

Controlled junction damping by microfabrication area engineering.

Preserved material quality during fabrication process.

Abstract

Van der Waals (vW) Josephson junctions (JJs) realized by stacking materials such as few-layered NbSe2, offers a new landscape to realize superconducting quantum devices with superior properties owing to its crystalline nature and defect-free junctions. For quantum technology, overdamped JJs are highly sought-after, whose realization demands precise control of junction capacitance by engineering the junction area using microfabrication techniques. NbSe2 is highly reactive and susceptible to damage during microfabrication processes. In this manuscript, we demonstrate both underdamped and overdamped NbSe2-NbSe2 JJs by controlling the junction area. We devise a minimally invasive microfabrication procedure, post-junction formation, to precisely control the junction area. The McCumber parameter characterizing the damping is extracted from the electrical transport measurements down to 130 mK. The results show that our sample fabrication recipe has preserved the material qualities and paved the way for the realization of scalable JJ devices on NbSe2 and similar systems.