Hybrid superinductance with Al/InAs

TL;DR

This paper presents microwave spectroscopy of Al/InAs Josephson junction chains demonstrating superinductance with high impedance and plasma frequency, analyzing loss mechanisms affecting their quality factors.

Contribution

It introduces epitaxial Al/InAs heterostructure chains exhibiting superinductance and investigates their microwave properties and loss mechanisms.

Findings

Impedance exceeds quantum resistance R_Q

High plasma frequency up to 12 GHz

Losses increase sharply with frequency

Abstract

We report microwave spectroscopy of Josephson junctions chains made from an epitaxial Al/InAs heterostructure. The chains exhibit superinductance, with characteristic wave impedance exceeding $R_{Q} = \hbar/(2e)^{2}$. The planar nature of the junctions results in a large plasma frequency, with no measurable deviations from ideal dispersion up to $12~\mathrm{GHz}$. Internal quality factors decrease sharply with frequency, which we describe with a simple loss model. The possibility of a loss mechanism intrinsic to the superconductor-semiconductor junction is considered.