Fig. 4: Controlling the qubit in the presence of the JQF.
From: Breaking the trade-off between fast control and long lifetime of a superconducting qubit
a, b Rabi frequency and Rabi decay time of the qubit as a function of the control amplitude represented as the square root of the photon flux \(\sqrt{\dot{n}}\). The top axes show the corresponding Rabi frequency of the JQF Ωf normalized by its external decay rate \({\gamma }_{{\rm{ex}}}^{{\rm{f}}}\). The red and blue data are the experimental results with and without the JQF, respectively. The red and blue solid lines depict numerical results with and without a transmon JQF, whereas the green dashed lines show simulation results using a two-level JQF. The insets are magnifications of the small amplitude region of the main plots. c Average gate error of the qubit as a function of the control pulse duration, obtained by randomized benchmarking. A Gaussian pulse is used for the qubit control, and the pulse interval is set to be twice the pulse duration. The black dashed line depicts the coherence limit. The error bars represent standard errors.
