Characterization of a fabrication process for the integration of superconducting qubits and RSFQ circuits

TL;DR

This paper presents a fabrication process based on Nb trilayer technology that enables the integration of superconducting qubits with RSFQ circuits, meeting the diverse requirements of both components at very low temperatures.

Contribution

Development and characterization of a Nb trilayer fabrication process suitable for integrating superconducting qubits and RSFQ circuits at cryogenic temperatures.

Findings

Josephson devices are suitable for qubit integration

Process operates effectively at 4.2 K

Fabrication meets requirements for both qubits and RSFQ circuits

Abstract

In order to integrate superconducting qubits with rapid-single-flux-quantum (RSFQ) control circuitry, it is necessary to develop a fabrication process that fulfills at the same time the requirements of both elements: low critical current density, very low operating temperature (tens of milliKelvin) and reduced dissipation on the qubit side; high operation frequency, large stability margins, low dissipated power on the RSFQ side. For this purpose, VTT has developed a fabrication process based on Nb trilayer technology, which allows the on-chip integration of superconducting qubits and RSFQ circuits even at very low temperature. Here we present the characterization (at 4.2 K) of the process from the point of view of the Josephson devices and show that they are suitable to build integrated superconducting qubits.