In-situ measurement and correction of pulse distortions in Si quantum-dot spin qubits

Fast electrical pulses are a key requirement for controlling semiconductor quantum dots. However, stray capacitance and other effects can distort these pulses. Distortions can be characterized and corrected at room temperature, but measuring distortions in-situ remains a challenge. In this work, we use detuning axis pulsed-spectroscopy (DAPS) to characterize baseband pulse distortions in a silicon double quantum-dot in its cryogenic operating environment. We develop a method to extract the characteristic impulse response of the system from the location of the DAPS peaks at different times, and we correct the distortions using standard techniques. We demonstrate that short-time distortions can be corrected for all finger gates on the device, limited by the timing resolution of our instrument. We demonstrate that by correcting the distortion, we can reduce the chirp of coherent exchange oscillations in a singlet-triplet qubit. Our results suggest a scalable and tuning-efficient method for characterizing pulse distortions in quantum-dot spin qubits.