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IEEE Transactions on Applied Superconductivity

Voltage-Tunable Vertical Nb/$\text{TiO}_{\text{x}}$/Nb Josephson Junction With High Transconductance and Broad Inductance Modulation

Hongmei Du, Dingding Li, Lili Wang

Published Jun 9, 2026• 0 citations
Publisher

Abstract

The ability to electrically control the critical current of a Josephson junction is a pivotal capability for developing reconfigurable superconducting electronics and quantum circuits. In this study, we report a voltage-tunable vertical Nb/$\rm{TiO}_{\rm{x}}$/Nb Josephson junction, featuring a top tuning electrode isolated by a 13 nm single-crystal hexagonal boron nitride (h-BN) dielectric. Applying a tuning voltage across this 2D insulator creates a high electric field, enabling the direct injection of high-energy quasi-particles into the junction. This mechanism facilitates the continuous suppression of the critical current to zero, accompanied by a broad modulation of the Josephson inductance. Our superconducting device exhibits a high transconductance ($\sim$1 mA/V) and allows the Josephson kinetic inductance to be tuned across a wide range ($\sim$0.01-1 nH). This voltage-tunable vertical architecture provides a compact device footprint, offering a promising platform for exploring dense, all-metallic superconducting circuits and future active cryogenic applications.

DOI
10.1109/tasc.2026.3701902

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