Atomic delocalisation as a microscopic origin of two-level defects in Josephson junctions

Abstract

Identifying the microscopic origins of decoherence sources prevalent in Josephson junction based circuits is central to their use as functional quantum devices. Focussing on so called "strongly coupled" two-level defects, we construct a theoretical model using the atomic position of the oxygen which is spatially delocalised in the oxide forming the Josephson junction barrier. Using this model, we investigate which atomic configurations give rise to two-level behaviour of the type seen in experiments. We compute experimentally observable parameters for phase qubits and examine defect response under the effects of applied electric field and strain.

arXiv comment13 pages, 18 figures

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Cited by in corpus (7)

• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits
• Electronic Decoherence of Two-Level Systems in a Josephson Junction
• The effect of atomic structure on the electrical response of aluminium oxide tunnel junctions
• Structural and Nanochemical Properties of AlOx Layers in $Al/Al{O}_x/Al$-Layer Systems for Josephson Junctions
• Probing hundreds of individual quantum defects in polycrystalline and amorphous alumina
• Constructing ab initio models of ultra-thin Al-AlOx-Al barriers