Time-Resolved Tomography of Quantum Gates

The performance of a quantum computer depends critically on a large number of highly-tuned parameters. Time dependence (drift) in these parameters is generally unheralded, but can have a pernicious and possibly devastating impact on quantum gate fidelities. Identifying the source of this drift is a critical first step on the path to mitigating it, but techniques to do so have been cumbersome at best. In this talk, we discuss a suite of quantum circuit experiments and data analysis tools that is capable of identifying and characterizing Fourier-sparse drift in quantum gates, measurements, and state preparation operations. By incorporating a model of the experiment that is aware of the controllable parameters, these tools can often help to establish the precise source of any unwanted time dependence. We illustrate our work with data from both simulation and experiment.