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arXiv · 2603.01844

Mapping g-factors and complex intervalley coupling in Si/SiGe by conveyor-mode shuttling

Mats Volmer·Tom Struck·Arnau Sala·Jhih-Sian Tu·Stefan Trellenkamp·Davide Degli Esposti·Giordano Scappucci·Hendrik Bluhm·Łukasz Cywiński·Lars R. Schreiber
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Abstract

As silicon spin qubit chips are increasing in qubit number and area, methods for the screening of qubit related material parameters become vital. Here we demonstrate the two-dimensional mapping of small variations of the electron g-factor of quantum dots formed in planar Si/SiGe quantum wells with precision better than $10^{-3}$ and with nanometer lateral resolution. We scan the electron g-factor across a 40 nm $\times$ 400 nm area and observe two g-factors per QD site which obey a striking symmetry and bimodal distribution across the area. These two g-factors relate to valley states of the electron in the quantum dot in agreement with a recent theoretical model. Using conveyor-belt shuttling of entangled electron spin pairs, complementary to the mapping of the local valley-splitting, we map the g-factor. We compare g-factor and valley splitting maps measured on the same device, and extract the complex intervalley coupling parameter along the shuttle trajectories applying a theoretical model of g-factor dependence on intervalley coupling. These maps will allow unprecedented insights into the spin-valley dynamics during qubit manipulation, readout and shuttling and serve as a benchmark for the engineering of Si/SiGe heterostructures for large-scale quantum chips.

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Mats Volmer, Tom Struck, Arnau Sala, Jhih-Sian Tu, Stefan Trellenkamp, Davide Degli Esposti, Giordano Scappucci, Hendrik Bluhm, Łukasz Cywiński, Lars R. Schreiber. 2026-03-02. Mapping g-factors and complex intervalley coupling in Si/SiGe by conveyor-mode shuttling. https://arxiv.org/abs/2603.01844

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