Modeling Si/SiGe quantum dot variability induced by interface disorder reconstructed from multiperspective microscopy

SiGe heteroepitaxial growth yields pristine host material for quantum dot qubits, but residual interface disorder can lead to qubit-to-qubit variability that might pose an obstacle to reliable SiGe-based quantum computing. By convolving data from scanning tunneling microscopy and high-angle annular...

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Bibliographic Details
Published in:npj quantum information 2024-03, Vol.10 (1), p.33-10, Article 33
Main Authors: Peña, Luis Fabián, Koepke, Justine C., Dycus, Joseph Houston, Mounce, Andrew, Baczewski, Andrew D., Jacobson, N. Tobias, Bussmann, Ezra
Format: Article
Language:English
Subjects:
639/301/1034/1035
639/766/119/1000/1017
639/766/483/2802
639/766/483/481
Atomistic models
Chemical vapor deposition
Classical and Quantum Gravitation
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Electrons
Interfaces
Laboratories
Measurement techniques
Molecular beam epitaxy
Physics
Physics and Astronomy
Quantum Computing
Quantum dots
Quantum Field Theories
Quantum information
Quantum Information Technology
Quantum Physics
Qubits
Relativity Theory
Scanning tunneling microscopy
Spintronics
String Theory
Tomography
Transmission electron microscopy
Variability
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Summary:SiGe heteroepitaxial growth yields pristine host material for quantum dot qubits, but residual interface disorder can lead to qubit-to-qubit variability that might pose an obstacle to reliable SiGe-based quantum computing. By convolving data from scanning tunneling microscopy and high-angle annular dark field scanning transmission electron microscopy, we reconstruct 3D interfacial atomic structure and employ an atomistic multi-valley effective mass theory to quantify qubit spectral variability. The results indicate (1) appreciable valley splitting (VS) variability of ~50% owing to alloy disorder and (2) roughness-induced double-dot detuning bias energy variability of order 1–10 meV depending on well thickness. For measured intermixing, atomic steps have negligible influence on VS, and uncorrelated roughness causes spatially fluctuating energy biases in double-dot detunings potentially incorrectly attributed to charge disorder. Our approach yields atomic structure spanning orders of magnitude larger areas than post-growth microscopy or tomography alone, enabling more holistic predictions of disorder-induced qubit variability.
ISSN:2056-6387
2056-6387
DOI:10.1038/s41534-024-00827-8