Planar Josephson junctions for sensors and electronics:Different geometry, new functionality

TL;DR

This paper reviews the unique advantages of planar Josephson junctions in superconducting electronics, emphasizing their enhanced sensitivity, miniaturization potential, and recent technological applications.

Contribution

It highlights recent advances and future prospects of planar Josephson junctions, focusing on their novel functionalities and technological applications.

Findings

Planar junctions improve magnetic field sensitivity.

They enable significant miniaturization of superconducting devices.

Recent applications include sensors, memory cells, and diodes.

Abstract

Josephson junctions are key elements in superconducting electronics. The most common type is the overlap (sandwich-type) junction, formed by vertically stacking two superconducting layers. In contrast, planar junctions are fabricated without overlap, at the edge of two superconducting films within a single plane. This geometric distinction has a significant impact on their physical properties. The planar geometry greatly enhances sensitivity to magnetic fields and improves impedance matching for terahertz (THz) devices. Its two-dimensional structure allows for simple and flexible electronic component design, enabling drastic miniaturization. Here I highlight recent advances in the application of planar junctions for novel technologies, including junction-on-cantilever sensors for super-resolution magnetic imaging, vortex-based memory cells, and programmable superconducting diodes. I will also discuss the general requirements, future perspectives, and key challenges in the evolving field of superconducting electronics.