Fig. 4: Phase relaxation times: \({T}_{2}^{\ast }\) from Ramsey measurement and T2 from spin-echo experiment.
From: Enhanced coherence of all-nitride superconducting qubits epitaxially grown on silicon substrate
Time-domain measurements showing a Ramsey fringe signal with \({T}_{2}^{\ast }=3.33\pm 0.30\;{{\upmu }}{{{{{\rm{s}}}}}}\) and b Hahn echo signal with \({T}_{2}=23.20\pm 5.21\;{{\upmu }}{{{{{\rm{s}}}}}}\). The pulse sequences for the measurements are shown in the insets. The pulse sequences include a \(\pi\) pulse with a 40 ns duration, \(\pi /2\) pulses with same duration but half the amplitude of the \(\pi\) pulses, and readout pulses with 400 ns duration. Here the driving frequency in both measurements is detuned by 5 MHz from the qubit frequency and each coherence time is determined by fitting with an exponentially decaying sinusoidal function. Statistical distributions of c the \({T}_{2}^{\ast }\) values and d the \({T}_{2}\) values with Gaussian fits (solid line).
