Tuning and operation of quantum dots using FPGA tools tailored for spin qubits

Main challenges in the development of a spin qubit quantum processor include tuning of large arrays of quantum dots to compensate for dot-to-dot variability and fast operation of gates which control the quantum dots for the implementation of error-correcting protocols.

Here, we offloaded parts of the tuning procedure from the lab computer to the instrument itself using the on-board field-programmable gate arrays (FPGAs) of Keysight’s Quantum Engineering Toolkit (QET).

The waveforms for a stability diagram measurement are generated on-the-fly without communication with the lab computer during the measurement. This allows video-mode measurements of small voltage regions for real time fine-tuning[ED1] . Furthermore, virtual gates can also be used by sending only the coefficient matrix since the compensation calculations are done in less than 100 ns in the FPGAs. With this approach, the tuning of a CMOS quantum dot has been done and compared to a traditional tuning procedure that does not use FPGAs. Moving the control logic of an experiment closer to the instruments and sample [ED2] allow for faster feedback and potentially faster measurements. It also offers a new tool to implement more scalable tuning and control for spin qubits.