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

Abstract

Long term operation of semiconductor spin qubits requires active stabilization of quantum dot potentials against low-frequency charge noise. Previous work demonstrated a gradient-descent feedback (GDFB) approach on a silicon double quantum dot utilizing transport current measurements. We extend such a GDFB approach in a silicon double quantum dot device with high-bandwidth rf-reflectometry readout 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 quick gate voltage updates, significantly increasing the effective feedback bandwidth compared to previous work. By operating with 8 steps per feedback cycle and an integration time of 25.6 $μ$s, this high speed stabilization scheme achieves a -6 dB noise suppression up to a bandwidth of 5 kHz. This effectively suppresses low frequency 1/f noise, maintaining device stability over longer time periods, and potentially enables real-time control in large-scale quantum dot arrays.