Fig. 2: Resonantly-driven singlet-triplet qubit.
a Rabi chevron pattern with a drive signal on vB12 of duration td and frequency fd. Initialization and readout of the \(\vert \widetilde{\uparrow \downarrow }\rangle\) state is described in the main text. \(\widetilde{P}\) is normalized with the application of either an IQ1 or an \({{{{\rm{X}}}}}_{\pi }^{{{{\rm{Q}}}}1}\) before the measurement sequence. Above each plot, the corresponding pulse sequence or circuit diagram is illustrated. b Dependence of the Rabi frequency, ΩST, on the drive amplitude A. The divergence from linearity (white dashed line) seen in the fast Fourier transform (inset) stems from the exponential dependence of the exchange to vB12. c Demonstration of rotation axis control via the addition of a phase ϕ. An \({{{{\rm{X}}}}}_{\pi /2}^{{{{\rm{ST}}}}}\) pulse initializes the system in a state pointing along the Y axis of the Bloch sphere. The Rabi oscillations disappear for ϕ = ± π/2, indicating that the drive axis and state align. d Randomized benchmarking of the single-qubit gates in the singlet-triplet subspace. We extract an average gate fidelity of \({{{\mathcal{F}}}}=99.68(2)\%\). e Ramsey (above) and Hahn echo (below) experiments fitted to a decaying exponential, with \({T}_{2}^{*}=1.9\,\mu {{{\rm{s}}}}\) and \({T}_{2}^{{{{\rm{H}}}}}=4.2\,\mu {{{\rm{s}}}}\) respectively. f Exponential decay fit of the Rabi oscillation with \({T}_{2}^{{{{\rm{R}}}}}=20.3\,\mu {{{\rm{s}}}}\).
