de Graaf, S E; Un, S; Shard, A G; Lindstrom, T (2022) Chemical and structural identification of material defects in superconducting quantum circuits. Materials for Quantum Technology, 2 (3). 032001

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Abstract

Quantum circuits show unprecedented sensitivity to external fluctuations compared to their classical counterparts, and it can take as little as a single atomic defect somewhere in a mm-sized area to completely spoil device performance.
For improved device coherence it is thus essential to find ways to reduce the number of defects, and thereby lowering the hardware threshold for achieving fault-tolerant large-scale error-corrected quantum computing. Given the evasive nature of these defects, the materials science required to understand them is presently in uncharted territories, and new techniques must be developed to bridge existing capabilities from materials science with the needs identified by the superconducting quantum circuit community.
In this paper we give an overview of methods for characterising the chemical and structural properties of defects in materials relevant for superconducting quantum circuits. We cover recent developments from in-operation techniques, where quantum circuits are used as probes of the defects themselves, to in situ analysis techniques and well-established ex situ materials analysis techniques. The latter is now increasingly explored by the quantum circuits community to correlate specific material properties with qubit performance. We highlight specific techniques which, given further development, seem especially promising and will contribute towards a future toolbox of material analysis techniques for quantum.

Item Type:	Article
Keywords:	superconducting, quantum circuits, material defects, surface analysis
Subjects:	Quantum Phenomena > Quantum Information Processing and Communication
Divisions:	Quantum Technologies
Identification number/DOI:	10.1088/2633-4356/ac78ba
Last Modified:	12 Sep 2022 14:24
URI:	https://eprintspublications.npl.co.uk/id/eprint/9514