It is customary to use arrays of superconducting quantum interference devices (SQUIDs) for implementing magnetic field-tunable inductors. Here, we demonstrate an equivalent tunability in a (SQUID-free) array of single Al/AlOx/Al Josephson tunnel junctions. With the proper choice of junction geometry, a perpendicularly applied magnetic field bends along the plane of the superconductor and focuses into the tunnel barrier region due to a demagnetization effect. Consequently, the Josephson inductance can be efficiently modulated by the Fraunhoffer-type supercurrent interference. The elimination of SQUIDs not only simplifies the device design and fabrication, but also facilitates a denser packing of junctions and, hence, a higher inductance per unit length. As an example, we demonstrate a transmission line, the wave impedance of which is field-tuned in the range of 4−8kΩ, centered around the important value of the resistance quantum h/(2e)2≈6.5kΩ.
@article{arxiv.2210.12119,
title = {Tuning the inductance of Josephson junction arrays without SQUIDs},
author = {Roman Kuzmin and Nitish Mehta and Nicholas Grabon and Vladimir E. Manucharyan},
journal= {arXiv preprint arXiv:2210.12119},
year = {2024}
}