High-fidelity flopping-mode single-spin operation via triple-dot orbital-band engineering
Abstract
Fast electrical spin rotations in quantum dots require strong spin-charge hybridization, but the same hybridization can increase sensitivity to detuning noise. In a double-quantum-dot (DQD) flopping-mode qubit, the sweet-spot width and the Rabi enhancement are both tied to the same orbital splitting, limiting post-fabrication optimization of the speed-coherence trade-off. Here, we demonstrate a GaAs triple-quantum-dot (TQD) flopping-mode qubit in which the detuning of the third dot, ϵ ₃₄ , provides an additional electrical tuning parameter for orbital-band flattening. Tuning ϵ ₃₄ flattens the qubit-frequency dependence on the detuning of the target DQD while maintaining strong spin-charge hybridization, enabling electrically driven Rabi frequencies above 100 MHz. We then use feedforward-neural-network (FNN) feedback to track slow qubit-frequency drift and connect this engineered operating point to high-fidelity gates. This feedback suppresses slow qubit-frequency fluctuations, reducing their standard deviation to 388 kHz, and yields a π /2 gate fidelity of 99.56% with a 4.05 ns gate time. These results identify TQD orbital-band engineering as an electrical route for tuning the speed-coherence trade-off, complementary to material-intrinsic spin-orbit coupling and fixed micromagnet geometry.
Related
- Single-mode 3×3 ZBLAN optical fiber coupler and application to unidirectional laser operation
- Engineering dissipation and control pulses for high-fidelity fault-tolerance quantum computing
- Graded Orbital Interface Engineering for Enhanced Damping-like Torque Efficiency
- Heavy-Hole--Light-Hole Mixing and Spin--Photon Coupling in Germanium Flopping-Mode Qubits
- Fast2Peak: High-Fidelity Restoration Algorithm by Single-Pixel Masking towards Real-Time Spectral Measurements
BibTeX
@article{matsumoto2026highfidelity,
title = {{High-fidelity flopping-mode single-spin operation via triple-dot orbital-band engineering}},
author = {Y. Matsumoto and X.-F. Liu and A. Ludwig and A. D. Wieck and K. Koike and T. Miyoshi and T. Fujita and A. Oiwa},
journal = {npj Quantum Information},
year = {2026},
month = oct,
doi = {10.1038/s41534-026-01400-1},
url = {https://www.nature.com/articles/s41534-026-01400-1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - High-fidelity flopping-mode single-spin operation via triple-dot orbital-band engineering
AU - Y. Matsumoto
AU - X.-F. Liu
AU - A. Ludwig
AU - A. D. Wieck
AU - K. Koike
AU - T. Miyoshi
AU - T. Fujita
AU - A. Oiwa
PY - 2026
DA - 2026/10/24
JO - npj Quantum Information
DO - 10.1038/s41534-026-01400-1
UR - https://www.nature.com/articles/s41534-026-01400-1
AB - Fast electrical spin rotations in quantum dots require strong spin-charge hybridization, but the same hybridization can increase sensitivity to detuning noise. In a double-quantum-dot (DQD) flopping-mode qubit, the sweet-spot width and the Rabi enhancement are both tied to the same orbital splitting, limiting post-fabrication optimization of the speed-coherence trade-off. Here, we demonstrate a GaAs triple-quantum-dot (TQD) flopping-mode qubit in which the detuning of the third dot, ϵ ₃₄ , provides an additional electrical tuning parameter for orbital-band flattening. Tuning ϵ ₃₄ flattens the qubit-frequency dependence on the detuning of the target DQD while maintaining strong spin-charge hybridization, enabling electrically driven Rabi frequencies above 100 MHz. We then use feedforward-neural-network (FNN) feedback to track slow qubit-frequency drift and connect this engineered operating point to high-fidelity gates. This feedback suppresses slow qubit-frequency fluctuations, reducing their standard deviation to 388 kHz, and yields a π /2 gate fidelity of 99.56% with a 4.05 ns gate time. These results identify TQD orbital-band engineering as an electrical route for tuning the speed-coherence trade-off, complementary to material-intrinsic spin-orbit coupling and fixed micromagnet geometry.
SN - 2056-6387
ER -