Impact of the local valley splitting on the coherence of conveyor-belt spin shuttling in 28Si/SiGe
5 affiliations
- 1JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- 2Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
- 3QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
- 4Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
- 5JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany. [email protected]
Abstract
Electron spins in silicon offer a promising path toward scalable, fault-tolerant quantum computing, with the potential to host millions of qubits. However, scaling up dense quantum-dot arrays and enabling qubit interconnections through shuttling are hindered by uncontrolled lateral variations of the valley splitting energy E VS . We map E VS across a 40 nm × 400 nm region of a 28 Si/Si 0.7 Ge 0.3 shuttle device and analyze the spin coherence of a single electron spin transported by conveyor-belt shuttling. We observe that the E VS varies over a wide range from 1.5 μeV to 200 μeV and is dominated by SiGe alloy disorder. In regions of low E VS and at spin-valley resonances, spin coherence is reduced and its dependence on shuttle velocity matches predictions. Rapid and frequent traversal of low- E VS regions induces a regime of enhanced spin coherence explained by motional narrowing. By selecting shuttle trajectories that avoid problematic areas on the E VS map, we achieve transport over tens of microns with coherence limited by the coupling to a static electron spin entangled with the mobile qubit. Our results provide experimental confirmation of the theory of spin decoherence of mobile electron spin-qubits and present practical strategies to integrate conveyor-mode qubit shuttling into silicon quantum chips.
Related
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BibTeX
@article{volmer2026impact,
title = {{Impact of the local valley splitting on the coherence of conveyor-belt spin shuttling in 28Si/SiGe}},
author = {M. Volmer and Tom Struck and Arnau Sala and Jhih‐Sian Tu and Stefan Trellenkamp and Davide Degli Esposti and Giordano Scappucci and Łukasz Cywiński and Hendrik Bluhm and Lars R. Schreiber},
journal = {Nature Communications},
year = {2026},
month = jun,
doi = {10.1038/s41467-026-74382-5},
url = {https://doi.org/10.1038/s41467-026-74382-5},
note = {CC BY},
}
RIS
TY - JOUR
TI - Impact of the local valley splitting on the coherence of conveyor-belt spin shuttling in 28Si/SiGe
AU - M. Volmer
AU - Tom Struck
AU - Arnau Sala
AU - Jhih‐Sian Tu
AU - Stefan Trellenkamp
AU - Davide Degli Esposti
AU - Giordano Scappucci
AU - Łukasz Cywiński
AU - Hendrik Bluhm
AU - Lars R. Schreiber
PY - 2026
DA - 2026/06/19
JO - Nature Communications
DO - 10.1038/s41467-026-74382-5
UR - https://doi.org/10.1038/s41467-026-74382-5
AB - Electron spins in silicon offer a promising path toward scalable, fault-tolerant quantum computing, with the potential to host millions of qubits. However, scaling up dense quantum-dot arrays and enabling qubit interconnections through shuttling are hindered by uncontrolled lateral variations of the valley splitting energy E VS . We map E VS across a 40 nm × 400 nm region of a 28 Si/Si 0.7 Ge 0.3 shuttle device and analyze the spin coherence of a single electron spin transported by conveyor-belt shuttling. We observe that the E VS varies over a wide range from 1.5 μeV to 200 μeV and is dominated by SiGe alloy disorder. In regions of low E VS and at spin-valley resonances, spin coherence is reduced and its dependence on shuttle velocity matches predictions. Rapid and frequent traversal of low- E VS regions induces a regime of enhanced spin coherence explained by motional narrowing. By selecting shuttle trajectories that avoid problematic areas on the E VS map, we achieve transport over tens of microns with coherence limited by the coupling to a static electron spin entangled with the mobile qubit. Our results provide experimental confirmation of the theory of spin decoherence of mobile electron spin-qubits and present practical strategies to integrate conveyor-mode qubit shuttling into silicon quantum chips.
SN - 2041-1723
ER -