Real-Time FPGA-Based Multi-Parameter Feedback Stabilization of a Silicon Double Quantum Dot

Long-term operation of semiconductor spin qubits requires active stabilization of quantum dot potentials against low-frequency charge noise. Wen et al. [1], demonstrated a gradient-descent feedback (GDFB) approach on a silicon double quantum dot, with feedback calculations executed on a desktop computer rather than dedicated hardware. We extend such a GDFB approach in a silicon double quantum dot device with high-bandwidth rf-reflectometry readout [2,3] by utilizing a field-programmable gate array, the OPX by Quantum Machines, for digital signal processing. The OPX enables continuous multi-parameter gradient calculation and rapid gate-voltage updates, significantly increasing the effective feedback bandwidth compared to previous work [1]. This high-speed stabilization scheme effectively suppresses charge-induced drift, maintaining device stability in the presence of faster charge fluctuations, and potentially enables real-time control in large-scale quantum dot arrays.

[1] C. Wen et al. 2025, Stabilization of a silicon double quantum dot based on a multi-dimensional gradient descent technique, Appl. Phys. Express 18, 015001 (2025).

[2] Tim J. Wilson et al. 2025, Fast and Sensitive Readout of a Semiconductor Quantum Dot Using an In-Situ Microwave Resonator with Enhanced Gate Lever Arm. arXiv.2510.00765

[3] Vigneau et al. 2023, Probing quantum devices with radio-frequency reflectometry Appl. Phys. Rev. 10, 021305 (2023)