Extended Data Fig. 2: Single qubit metrics.
From: Industry-compatible silicon spin-qubit unit cells exceeding 99% fidelity
a,b, Spin relaxation of qubit 1 (a) and 2 (b) spin up to the ground state \(| \downarrow \downarrow \rangle \). Curves are fitted to an exponential decay resulting in a relaxation time of T1,Q1 = 2.4(2) s (a = 0.999, b = 0.847) and T1,Q2 = 6.3(6) s (a = 0.989, b = 1.183), respectively. For long wait times, the pure \(| \downarrow \downarrow \rangle \) state decays to its thermal equilibrium following the Fermi-Dirac distribution at finite temperatures. c,d, Ramsey experiment for qubit 1 (c) and 2 (d) fitted to a sinusoidal exponential decay resulting in a coherence time of \({T}_{2,{\rm{Q}}1}^{* }=30.2(6)\,{\rm{\mu }}{\rm{s}}\) (a = −0.498, fdet = 95 kHz, b = 1.874, c = 0.498) and \({T}_{2,{\rm{Q}}2}^{* }=29.1(6)\,{\rm{\mu }}{\rm{s}}\) (a = −0.488, fdet = 102 kHz, b = 1.884, c = 0.499), respectively. The oscillation is induced by a phase shift corresponding to a 100 kHz detuning. Every data point is averaged for 1,000 repeats, each integrating the readout signal for tint = 100 μs. We use real-time Larmor frequency feedback between repeats using the protocol described in ref. 39. e,f, Hahn echo experiment for qubit 1 (e) and 2 (f) fitted to an exponential decay resulting in a coherence time of \({T}_{2,{\rm{Q}}1}^{{\rm{Hahn}}}=445(6)\,{\rm{\mu }}{\rm{s}}\) (a = 0.931, b = 1.263, c = 0.035) and \({T}_{2,{\rm{Q}}2}^{{\rm{Hahn}}}=803(6)\,{\rm{\mu }}{\rm{s}}\) (a = 0.908, b = 3.125, c = 0.040), respectively. We measure all six single qubit projections and fit the state purity γstate. Error bars represent the 95% confidence level.
