Fig. 2: Qubit properties.
From: High-fidelity geometric quantum gates exceeding 99.9% in germanium quantum dots
a The Rabi chevron pattern: singlet state probability PS as a function of τburst and Δf. b Rabi frequency (blue triangles) and the Q factor (red circles) measured under different microwave power \({P}_{{{\rm{MW}}}}^{1/2}\), showing no saturation. The largest fRabi of 19 MHz and Q factor of 39.78 are achieved. Inset: PS as a function of τburst along the red dashed line in (a). The red solid line represents the fitting result, yielding a Rabi frequency of 11.56 MHz and Q factor of 18.04. c Ramsey fringe obtained by varying the idle time τidle, with the fitted dephasing time \({T}_{2}^{*}\) of 136 ns. The red solid line represents the fitting result. d Coherence decay under CPMG sequences as a function of total idle time for different Nπ. Inset: \({{T}_{2}}^{{{\rm{CPMG}}}}\) as a function of Nπ. For the largest Nπ = 230, we obtain \({{T}_{2}}^{{{\rm{CPMG}}}}\) = 6.75 μs.
