Fig. 4: Qubit frequency variations over stable voltage periods.

(obtained from Fig. 2). Each plot corresponds to the qubit frequency variations in the stable period indicated above the panel. In each panel, the top six subpanels correspond to qubit frequency variations, whilst the bottom subpanel shows the mixing chamber temperature at the time of data collection. a Data taken at base temperature of 12.8 mK. b Data taken while the mixing chamber temperature was varied from 12.8 mK to about 800 mK. We observe that qubit frequency shifts globally correlate with the mixing chamber temperature over this period. c Data taken at 200 mK before changing to 300 mK. The temperature was no longer logged after 18/06. d Data taken at 200 mK.