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Baseband control of single-electron silicon spin qubits in two dimensions

Florian K. Unseld, Brennan Undseth, Eline Raymenants, Yuta Matsumoto, Saurabh Karwal, Oriol Pietx-Casas, Alexander S. Ivlev, Marcel Meyer, Amir Sammak, Menno Veldhorst, Giordano Scappucci, Lieven M. K. Vandersypen

arXiv: 2412.05171v1 (cond-mat.mes-hall)
main text with 12 pages and 5 figures, methods and extended data and supplementary materials with 22 pages and 11 figures and 1 table, in a single file
Licence : CC BY 4.0

Résumé : Micromagnet-enabled electric-dipole spin resonance (EDSR) is an established method of high-fidelity single-spin control in silicon. However, the resulting architectural limitations have restrained silicon quantum processors to one-dimensional arrays, and heating effects from the associated microwave dissipation exacerbates crosstalk during multi-qubit operations. In contrast, qubit control based on hopping spins has recently emerged as a compelling primitive for high-fidelity baseband control in sparse two-dimensional hole arrays in germanium. In this work, we commission a $^{28}$Si/SiGe 2x2 quantum dot array both as a four-qubit device with pairwise exchange interactions using established EDSR techniques and as a two-qubit device using baseband hopping control. In this manner, we can evaluate the two modes of operation in terms of fidelity, coherence, and crosstalk. We establish a lower bound on the fidelity of the hopping gate of 99.50(6)%, which is similar to the average fidelity of the resonant gate of 99.54(4)%. Lowering the external field to reach the hopping regime nearly doubles the measured $T_2^{\mathrm{H}}$, suggesting a reduced coupling to charge noise. Finally, the hopping gate circumvents the transient pulse-induced resonance shift. To further motivate the hopping gate approach as an attractive means of scaling silicon spin-qubit arrays, we propose an extensible nanomagnet design that enables engineered baseband control of large spin arrays.

Soumis à arXiv le 06 Déc. 2024