Kavli Affiliate: Giordano Scappucci
| First 5 Authors: Mats Volmer, Mats Volmer, , ,
| Summary:
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 $1.5 , mu$eV to $200
, mu$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.
| Search Query: ArXiv Query: search_query=au:”Giordano Scappucci”&id_list=&start=0&max_results=3