TY  - EJOUR
AU  - Volmer, Mats
AU  - Struck, Tom
AU  - Tu, Jhih-Sian
AU  - Trellenkamp, Stefan
AU  - Esposti, Davide Degli
AU  - Scappucci, Giordano
AU  - Cywiński, Łukasz
AU  - Bluhm, Hendrik
AU  - Schreiber, Lars R.
TI  - Reduction of the impact of the local valley splitting on the coherence of conveyor-belt spin shuttling in $^{28}$Si/SiGe
PB  - arXiv
M1  - FZJ-2025-05266
PY  - 2025
AB  - Silicon quantum chips 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 x $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 $1.5 \, μ$eV to $200 \, μ$eV 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 only 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.
KW  - Quantum Physics (quant-ph) (Other)
KW  - FOS: Physical sciences (Other)
LB  - PUB:(DE-HGF)25
DO  - DOI:10.48550/ARXIV.2510.03773
UR  - https://juser.fz-juelich.de/record/1049183
ER  -