Method for assessing atomic sources of flicker noise in superconducting qubits

Almog Reshef,Maytal Caspary Toroker

doi:10.1038/s41524-021-00622-5

Almog Reshef, Maytal Caspary Toroker

Open Access

https://doi.org/10.1038/s41524-021-00622-5

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Abstract

Flicker noise causes decoherence in Josephson junction-based superconducting qubits, thus limiting their practical potential as building blocks for quantum computers. This is due to limited length and complexity of executable algorithms, and increased dependency on error-correcting measures. Therefore, identifying and subsiding the atomic sources of flicker noise are of great importance to the development of this technology. We developed a method that combines ab initio DFT calculations and quantum dynamics to model charge transport across a Josephson junction, by which it is possible to more accurately assess different defects as sources of flicker noise. We demonstrate the use of our method in an investigation of various atomic defects, including vacancies, trapping, and substitutions, in an Al|Al2O3|Al Josephson junction. This demonstration both reveals weaknesses in previous attempts to pinpoint the atomic sources of flicker noise and highlights new candidates.

Highlights

Quantum computers (QC) are a topic for theoretical research for nearly 40 years, but only in the last decade, advancement in fabrication and design processes resulted in limited but functional QC processors
These two-level system (TLS) can arise from defects in the material, and their collective behavior manifests itself as low-frequency flicker noise[1,2,3,4]
The purpose of this paper is to showcase the use of our method for assessing atomic sources of flicker noise in JJbased superconducting qubits

Summary

Introduction

Quantum computers (QC) are a topic for theoretical research for nearly 40 years, but only in the last decade, advancement in fabrication and design processes resulted in limited but functional QC processors. One such type of promising design is based on superconducting materials used for the fabrication of electrical components called Josephson junctions (JJ). These TLSs can arise from defects in the material, and their collective behavior manifests itself as low-frequency flicker noise[1,2,3,4]

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