A spin-triplet encoding based on valley-singlet states makes shuttling fidelities in Si/SiGe quantum wells higher and more robust to small valley splittings by suppressing Landau-Zener excitations.
Impact of the local valley splitting on the coherence of conveyor-belt spin shuttling in $^{28}$Si/SiGe
6 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
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.
verdicts
UNVERDICTED 6representative citing papers
Experimental demonstration of Ge concentration modulations in Si quantum wells with periods from 2.00 nm to 0.49 nm (including at k0 and 2k0/3), characterized by X-ray and STEM showing high homogeneity and gradients up to 20 at-%/nm, with k·p simulations suggesting valley splitting enhancement in 2k
Resource estimation for magic-state distillation on silicon spin qubits finds 42% overhead reduction via optimized pulses and ~3x physical footprint reduction with biased codes versus surface code.
Theoretical expressions for singlet return probability in multivalley Si double quantum dots near spin-valley resonances are derived, accounting for valley occupations, and validated against experiments to map valley splittings and probe g-factor dependence.
Theoretical study of flopping-mode qubits in Si/SiGe showing that high-fidelity operation is achievable across valley configurations when pulses are tuned for weak noise or when valley splittings are large and phase differences small for strong noise.
A review summarizing spin qubit platforms, long-range coupling methods, and a proposal for topological linking toward scalable quantum information processing.
citing papers explorer
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Using a spin-triplet encoding to enhance shuttling fidelities in Si/SiGe quantum wells
A spin-triplet encoding based on valley-singlet states makes shuttling fidelities in Si/SiGe quantum wells higher and more robust to small valley splittings by suppressing Landau-Zener excitations.
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Sharp periodic Ge concentration modulations beyond the conduction band valley wavevector $k_0$ in nuclear spin-free Si quantum wells
Experimental demonstration of Ge concentration modulations in Si quantum wells with periods from 2.00 nm to 0.49 nm (including at k0 and 2k0/3), characterized by X-ray and STEM showing high homogeneity and gradients up to 20 at-%/nm, with k·p simulations suggesting valley splitting enhancement in 2k
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Hardware-Tailored Resource Estimation for Magic-State Distillation on Silicon Spin Qubits
Resource estimation for magic-state distillation on silicon spin qubits finds 42% overhead reduction via optimized pulses and ~3x physical footprint reduction with biased codes versus surface code.
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Singlet-triplet oscillations in multivalley Si double quantum dots
Theoretical expressions for singlet return probability in multivalley Si double quantum dots near spin-valley resonances are derived, accounting for valley occupations, and validated against experiments to map valley splittings and probe g-factor dependence.
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Theory of spin qubits and the path to scalability
A review summarizing spin qubit platforms, long-range coupling methods, and a proposal for topological linking toward scalable quantum information processing.