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arXiv · 2412.19795

g-factor theory of Si/SiGe quantum dots: spin-valley and giant renormalization effects

Benjamin D. Woods·Merritt P. Losert·Robert Joynt·Mark Friesen
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Abstract

Understanding the $g$-factor physics of Si/SiGe quantum dots is crucial for realizing high-quality spin qubits. While previous work has explained some aspects of $g$-factor physics in idealized geometries, the results do not extend to general cases and they miss several important features. Here, we construct a theory that gives $g$ in terms of readily computable matrix elements, and can be applied to all Si/SiGe heterostructures of current interest. As a concrete example, which currently has no $g$-factor understanding, we study the so-called Wiggle Well structure, containing Ge concentration oscillations inside the quantum well. Here we find a significant renormalization of the $g$-factor compared to conventional Si/SiGe quantum wells. We also uncover a giant $g$-factor suppression of order $\mathcal{O}(1)$, which arises due to spin-valley coupling, and occurs at locations of low valley splitting. Our work therefore opens up new avenues for $g$-factor engineering in Si/SiGe quantum dots.

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Benjamin D. Woods, Merritt P. Losert, Robert Joynt, Mark Friesen. 2024-12-27. g-factor theory of Si/SiGe quantum dots: spin-valley and giant renormalization effects. https://arxiv.org/abs/2412.19795

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