Fig. 4: Operation of the qubit at elevated temperatures.
a Temperature dependence of qubit lifetime. The blue points are the measured T1 values. The gray points with dashed lines represent the expected T1 degradation due to decreasing Qind from the rise in the quasiparticle population as the qubit temperature increases. We use the measured qubit temperature as input to our model. b Temperature dependence of qubit coherence time. The shaded region is the error from the T2R fit. T2R does not show significant variation with temperature. c Excited-state probability, Pe (left) and qubit temperature (right) as a function of mixing chamber temperature. The upper bound of the shaded region represents the uncertainty from the qubit histogram fit. The lower bound of the shaded region also accounts for the uncertainty associated with overestimating the \(\left\vert e\right\rangle\) state population due to excess \(\left\vert f\right\rangle\) state population in the qubit histogram. The crosses represent data which was taken with a different readout parameter compared to the circles, which were chosen due to the reduction in T1 at higher temperatures.
