Fig. 3: Quantum control of a nanotube gatemon qubit.
a Rabi oscillations as a function of drive frequency fd and pulse duration τRabi. The two observed chevron patterns correspond to the qubit transition at 4.32 GHz (white arrow) and a two-photon transition to the second excited state 71 MHz below (black arrow). The signal is the change of cavity transmission S21 compared to the ground state transmission \({S}_{21}^{| g\left.\right\rangle }\). b Relaxation measurement (blue points) following a π-pulse. The exponential fit (black line) leads to T1 = 191 ± 2 ns. c Ramsey oscillations as a function of drive frequency fd and time delay τRamsey between two π/2 Gaussian pulses. The oscillation frequency is given by the detuning of the drive from the qubit frequency. d Ramsey oscillations measured at +20 MHz detuning (blue points), which is a line cut in (c) indicated as dashed line. The fit of an exponentially decaying cosine (black line) results in a coherence time of \({T}_{2}^{*}=228\pm 12\,{{{{\rm{ns}}}}}\). All measurements were performed on device B at Vg = −4.2376 V.
