Real-time quantum dot stability diagram measurement using on-the-fly generated waveforms

Stability diagrams are essential to understand the energy landscape of quantum dots and tune them into the spin-qubit regime, but the voltage space to cover increases significantly with the number of quantum dots. Many advanced techniques have been proposed in the last few years to minimize the number of measurements needed to extract valuable information, where the speed bottleneck often comes from the means available to implement the algorithm itself, the measurement platform. To break this threshold, we explored Keysight’s Quantum Engineering Toolkit (QET) to program typical experimental routines and take advantage of the on-board field-programmable gate arrays (FPGAs). A novel dedicated module allows the user to define waveforms generated dynamically directly at the FPGA level, removing previously lengthy data transactions between sequences within an experiment. With this approach, we can perform multiple stability diagram measurements in under a second and virtual gate calculations in under 100 ns. The flexibility of the FPGA programming also allows the routines to be adapted to more complex measurements that may include accelerated machine learning, statistical models and local feedback loops. These tools are a step towards the scalable control of spin qubits using cryogenic electronics.