Ternary Metal Oxide Substrates for Superconducting Circuits

TL;DR

This study investigates two ternary metal oxide substrates, MgAl2O4 and LaAlO3, demonstrating their potential to improve superconducting quantum circuits by reducing surface imperfections and increasing device quality factors.

Contribution

The paper introduces MgAl2O4 as a novel substrate for superconducting devices and compares its performance with LaAlO3, emphasizing material exploration for enhanced quantum circuit coherence.

Findings

LaAlO3 devices show three times higher quality factors than previous devices.

MgAl2O4 outperforms LaAlO3 despite surface disorder.

Material and surface preparation are crucial for high-performance superconducting circuits.

Abstract

Substrate material imperfections and surface losses are one of the major factors limiting superconducting quantum circuitry from reaching the scale and complexity required to build a practicable quantum computer. One potential path towards higher coherence of superconducting quantum devices is to explore new substrate materials with a reduced density of imperfections due to inherently different surface chemistries. Here, we examine two ternary metal oxide materials, spinel (MgAl2O4) and lanthanum aluminate (LaAlO3), with a focus on surface and interface characterization and preparation. Devices fabricated on LaAlO3 have quality factors three times higher than earlier devices, which we attribute to a reduction in interfacial disorder. MgAl2O4 is a new material in the realm of superconducting quantum devices and, even in the presence of significant surface disorder, consistently outperforms LaAlO3. Our results highlight the importance of materials exploration, substrate preparation, and characterization to identify materials suitable for high-performance superconducting quantum circuitry.