Characterizing frequency fluctuations induced non-Markovian noise in superconducting qubits

Non-Markovian noise is an important source of nosie in superconducting qubits available today. In this presentation we show that including the effects of non-Markovian noise allows us to have a model that can accurately capture the device physics. We further develop a method to perform experiments on a superconducting qubit quantum computer to resolve qubit frequency fluctuations at different time scales, and show that the frequency fluctuations are the dominant source of observed non-Markovian noise in the device. The methods allow us to see the effects of quasiparticle induced charge parity fluctuations as well as frequency fluctuations due to two level fluctuators. We analyse the magnitude, rate, and symmetry of the charge parity fluctuations, as well as fluctuations in the charge parity frequency splitting. The understanding of these non-Markovian noise sources provided by our model and by our experiments allow to optimize the calibration of the devices and to further mitigate the effects of noise.