Automated tuning of encoded spin qubits with a directed acyclic graph

Encoded spin qubits in silicon are an appealing basis for practical quantum computers. A major challenge for realizing this potential is the need for calibration, ranging from isolating electrons to calibrating their individual characteristics. This is especially important as devices grow in size and complexity; recent progress towards automating the process spans many aspects [1]. Intel is leveraging its semiconductor fabrication expertise to make spin qubit platforms at wafer scale [2, 3], increasing the need for robust and scalable automation. To reliably and extensibly integrate different calibrations into a single automated process we develop a calibration graph [4] for exchange-only spin qubits. We experimentally validate our calibration graph for both tuning up and maintaining the calibrations of two exchange-only qubits in an Intel Tunnel Falls device.

[1] J. P. Zwolak and J. M. Taylor. Rev. Mod. Phys. 95, 011006 (2023).

[2] S. Neyens, et al. Nature, 629, 80-85 (2024).

[3] H. C. George, et al. arxiv:2410.16583 [mes-hall] (2024).

[4] J. Kelly, P. O’Malley, M. Neeley, H. Neven, and J. M. Martinis. arXiv:1803.03226 [quant-ph] (2018).